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Posts Tagged ‘adrenaline’

A-Z Principal Drugs (nisoldipine - oxerutins)

Saturday, June 27th, 2009

nisoldipine A calcium channel blocking agent of the nifedipine type. Used in mild to moderate hypertension pertension and in the prophylaxis of chronic angina.
Dose: 10 ing once daily before breakfast with adequate fluid, slowly increased as required up to 40 mg daily. Tablets to be swallowed whole, not chewed or crushed. It may react with sonic other drugs in common use, and grapefruit juice should be avoided. (Syscor). See pages 114 & 148, and ‘Fables 4 & 21.
nitrazepam A benzodiazepine used as a mild hypnotic when some degree of daytime sedation is acceptable.
Dose: 5-10 mg at night, with reduced doses for elderly patients, and in renal and’ hepatic dysfunction. Care is necessary in respiratory depression. Some dependence on nitrazepam may occur, so extended treatment should be avoided. The combined use of alcohol increases the hypnotic action. (Mogadon; Remnos). Set: page 152 and Table 22.
Nitrocine A solution of glyceryl trinitrate, for i.v. infusion in myocardial ischaemia and refractory angina.
nitrofurantoin An antibacterial agent with a wide range of activity against the majority of urinary pathogens. It is of value in cystitis and pyelitis, and in renal infections that have become resistant to other drugs. It is also used prophylactically but extended use requires care.
Dose: 400 mg daily; 50-100 mg at night for prophylaxis. It is ineffective in an alkaline urine. Nausea, rash and peripheral neuropathy are side-effects, and acute and chronic pulmonary reactions have been reported. (Furadantin; Macrobid).
nitroglycerine See glyceryl trinitrate. nitroprusside See sodium nitroprusside.
nitrous oxide The oldest inhalation anaesthetic. Supplied in blue cylinders, it is widely used for induction and as part of a mixed anaesthetic system. It is also used as
a 50% oxygen mixture as an inhalation analgesic in obstetrics.
nizatidine A potent and selective H,-receptor antagonist chemically distinct from cimetidine or ranitidine.
Dose: in the treatment of benign duodenal and gastric ulcer, single doses of 300 mg daily, taken in the evening, or 150 mg twice a day, and continued for 4 weeks, or for s weeks in gastric ulcer including non-steroidal anti-inflammatory agent (NSAID) -induced ulceration. Occasionally given by i.v. infusion in doses of300mg daily. For prophylactic maintenance, doses of 150 mg daily may be given for up to a year. Reduced doses should be given in renal impairment. Side-effects include headache, niyalgia, cough, pruritus and abnormal dreams. (Axi& Zinga). See page 162 and “Fable 27.
non-steroidal anti-inflammatory drugs (NSAIDs) A group of drugs with analgesic anti-inflammatory properties widely used in arthritic, rheumatoid and related conditions. The response to a NSAID and the incidence and severity of side-effects such as gastric irritation and renal toxicity vary considerably, and the best NSAID for an individual patient is the one that gives optimum relief with minimal side-effects. The NSAIDs, of which aspirin is the oldest example, act by interrupting the biosynthesis of prostaglandins from arachidonic acid, in which process the enzyme cycleoxygenase (COX) plays a key role. It is now known that COX exists in two forms identified as COX-1 and COX-2. The anti-inflammatory action of the NSAIDs appears to be linked with the inhibition of COX-2, whereas the unwanted side-effects are associated with COX- I inhibition. Different NSAIDs have varying degrees of activity against the different forms of COX, which may explain the differences in the therapeutic response and the incidence of side-effects. Recently, a NSAID (meloxicain) has been introduced that has a more selective inhibitory action on COX-2, with which the incidence of side-effects appears to be lower than with the older drugs, and so may have therapeutic advantages. In general, the response to a NSAID may take 1-3 weeks to develop fully, but monitoring for gastrointestinal bleeding may be advisable if treatment is extended. A NSAID should not be given to a patient with a history of asthma or hypersensitivity, nor when peptic ulcer is suspected or present. In all cases, treatment should be commenced with the lowest recommended dose, and caution is necessary in the elderly, and when renal or hepatic function is impaired. See page 165 and Table 29.
Dose: 20 100 mg daily. It is given in nocturnal enuresis in doses of 10-20 mg nightly, but the duration of treatment should not exceed 3 months. (Allcgron). See page 128 and Table 11.
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noradrenaline (norepinephrine) The pressor hormone released at sympathetic nerve endings when such nerves are stimulated. It is also present with adrenaline in the medulla of the adrenal gland. It raises blood pressure mainly by a general vasoconstriction, whereas adrenaline acts by constricting the peripheral vessels and increasing the cardiac output. Noradrenaline is given by slow i.v. infusion in the treatment of shock, peripheral failure, and low blood pressure states, but the response may fluctuate with small variations in dose. The value of vasoconstrictors in shock is now questioned, as in shock the peripheral resistance may well be high, and the blood supply to essential organs such as the kidneys may be reduced.
Dose: 2-20 pg/niin, based on need and response. Great care must be taken to avoid extra-venous injection. (Levophed).
norethisterone An orally active progestogen. Used in amenorrhoea, functional uterine bleeding and dysmenorrhoea. Dose: 5-20 mg daily. In breast cancer, large doses up to 60 mg daily have been used. To postpone menstruation, 15 mg daily for 3 days have been used. In small doses, and in association with an oestrogen, norethisterone and related drugs are widely used as oral contraceptives. See page 264.
norfloxacin A quinolone antibacterial with the actions, uses and side-effects of cinoxacin and other quinolones.
Dose: in acute urinary tract infections, 801) mg daily for 3-10 days: in chronic infections continued for up to 12 weeks. ( I Itinor).
norgestrel (levonorgestrel) An orally active progesterone-like drug and inhibitor of ovulation. Used as a constituent of mixed oral contraceptive products, and as a ‘progestogen -only’ oral contraceptive. See page 264.
nortriptyline A tricyclic antidepressant with actions, uses and side-effects similar to those of amitriptyline, but with a reduced sedative activity.
NSAIDs See non-steroidal anti-inflamma-
tory drugs, page 168 and Table 29.
nystatin A fungicidal antibiotic, used in the treatment of intestinal, vaginal and superficial candidiasis. Oral tablets contain 500 000 units, pessaries contain 100 000 units; cream and ointment 1%. Dose: (oral) 2 million units daily. It is also used as pastilles of 100000 units for mouth infections.
octreotide A synthetic compound that inhibits the release of the growth hormone. It is used in acromegaly, which is caused by an overproduction of the growth hormone by a pituitary tumour and it is given in doses of 100-200pg 8-hourly by s.c. injection. It is also used in the symptomatic treatment of the carcinoid syndrome, in which the release of vasoactive substances by a gastro- pancreatic tumour causes flushing and severe diarrhoea.
Dose: 30 pg by s.c. injection, increased as needed up to 600 pg daily. It has no action on the cause of the syndrome. It is used occasionally in terminal care to reduce intestinal secretions and vomiting. Dose: 300-600 pg by s.c. infusion. (Sandostatin).
oestradloIlThe oestrogenic hormone controlling ovulation and menstruation. It has been used to control menopausal symptoms in doses of 10-20pg daily, but skin patches are now preferred for hormone replacement therapy (HRT). It is used occasionally as s.c. implants for long-term treatment. Oestradiol is also present in some cream preparations for menopausal atrophic vaginitis.
oestriol A natural oestrogen used in intravaginal cream to relieve the atrophic vaginitis and kraurosis vulvae associated with the menopause. Also given in doses of 1-32 mg daily for the genito-urinary symptoms linked with infections in oestrogen deficiency states. (Ovestin).

ofloxacin A fluorinated quinolone with the actions, uses and side-effects of other quinolones such as ciprofloxacin and norfloxacin. It is used mainly in urinary and lower respiratory tract infections. Dose: wii nig daily as a single morning dose. Dose in severe infections 200-400 mg daily by i.v. injection. An occasional side-effect is tendon damage with pain and inflammation, which requires immediate withdrawal of the drug. Exposure to strong sunlight should be avoided. (Tarivid). Also used as eye drops (0.3%) for superficial eye infections. (Exocin).
olanzapineV An antipsychotic agent for the treatment of schizophrenia. It has a more selective action on certain 5-H’I'- receptors, and is less likely to cause extra-pyramidal side-effects.
Dose: 10 mg as a single daily dose, slowly increased as required. Maintenance dose 5-20 mg daily. Side-effects include
sedation and weight gain. (Zyprexa). See page 168 and Table 30.
olsalazine A compound formed from mesalazine, and used in the treatment of ulcerative colitis. It is more slowly
absorbed, and reaches the colon largely unchanged, where it is broken down by intestinal bacteria to release the active metabolite mesalazine.
Dose: 1-3 g daily in acute mild ulcerative colitis; I g daily for maintenance, often for long periods. The common side-effect is a watery diarrhoea. Salicylate sensitivity is a contraindication. Patients are now advised to report any bruising, bleeding or
malaise. I( a blood dyscrasia is suspected, a blood count should be made -,in(] the drug withdrawn. (Dipentuni). See page 172 and Table 32.
ondansetron A potent antiemetic, of value in the nausea and vomiting associated with cancer chemotherapy. Such vomiting appears to be induced by the release of serotonin, which acts on receptors in the gut as well as stimulating the chernoreceptor trigger zone in the brain. Ondansetron is a specific (5—HT,) serotonin blocking agent, and is given before the commencement of cytotoxic treatment or radiotherapy.
Dose: 24 mg daily; in severe vomiting an initial dose of 8 ing is given by slow i.v. injection, followed by I ing/hrly for 24 hours by continuous i.v. infusion, followed by oral therapy. Side-effects are an initial sense of warmth, headache an(] constipation. (Zofran). See page 158.
topium The dried juice from the capsules of the opium poppy. See morphine.
orciprenaline A synipathomimetic agent with the bronchodilator properties of isoprenaline. It is used for the relief of obstructive airway conditions, although more selective drugs of the salbutarnol type are often preferred.
Dose: up to 80 ang daily; by aerosol inhalation up to 12 puffs (9mg) daily. Side-effects include tremor and tachycardia. (Ahiperil). See page 118 and Table 6.
orphenadrine A spasmolytic drug, used in the treatment of parkinsonism, and for the relief of voluntary muscle spasm. Dose: 150-400 nig daily. It may also be given by i.m. injection in doses of 60 mg. In parkinsonism it tends to control the rigidity more than the tremor. Side-effects are anticholinergic and include dryness of the mouth, dizziness and visual disturbances. Weight gain has occurred with high doses. (Disipal; Norflex). See
page 160 and Table 26.
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omeprazole An inhibitor of the enzyme I I*K’A'I’Pase.’rhat enzyme controls the final stage of gastric acid production, and its inhibition by omeprazole is of value in peptic ulcer resistant to H, receptor antagonists, and in reflux oesophagitis, where such agents are not always effective. Dose: in benign gastric and duodenal ulcer, 20-40 ing as it single daily dose for 4-8 weeks. Larger doses may be required in the Zollinger—Ellison syndrome. Side-effects such as nausea, gasiro-intestinal disturbances and headaches are usually mild. (Losec). See page 162 and Table 27.
oxazepam A benzodiazepine with the actions, uses and side-effects of diazepam. It is useful in acute anxiety and panic states.
Dose: 45-120 mg daily. See page 117 and Table 5.
oxerutins A mixture of rutosides (flavonoid derivatives) which is claimed to reduce capillary fragility and permeability. It has been used in venous disorders of the lower limbs.
Dose: 750-1000 nig daily. (Paroven).

A-Z Principal Drugs (lithium succinate - menthol)

Saturday, June 27th, 2009

lithium succinate Lithium succinate appears to have sonic antifungal and anti-inflammatory properties, and is used as an 8% ointment for seborrhoeic dermatitis. (Ftalith).
lodoxamide A mast cell stabilizer similar to sodium cromoglycate. Used as eye drops (0.1%) in allergic conjunctivitis. (Alomide).
Dose: in acute diarrhoea, 4 mg initially, followed by 2 nig as required, up to a maximum of 16 ing daily. In chronic diarrhoea, 4-8 nig daily, but care is necessary in the elderly to avoid faecal impaction. Loperamide is not suitable for children under 4 years of age, nor in patients with liver disease, as it may cause undesirable sedation. (Iniodium).
loprazolam A benzodiazepine hypnotic used mainly in the short-term treatment of insomnia and nocturnal arousal. Dose: 1-2 nig at bedtime. Side-effects include drowsiness, dizziness, dry mouth and headache. See page 152 and Table 22.
loratadine An antihistamine with the general action of that group of drugs, but with reduced sedative side-effects.
Dose: 10 nig dailv. (Clarityn). See page I 10 and Table 2.
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lofepramine An antidepressant of the irnipramine group, with similar actions and uses, but reduced sedative and anticholinergic side-effects.
Dose: 140-210 nig daily. (Gamanil). See page 128 and Table 11.
lofexidine A narcotic antagonist. It has a selective blocking action on brain nor-adrenaline, and is used for the rapid relief of opioid withdrawal symptoms associated with central sympathetic activity.
Dose: 200 pg twice a day, slowly increased as required over 7-10 days, before withdrawal over 2-4 days. Care is necessary in cardiac insufficiency and bradycardia. (Britl.olex).
lomotil A preparation of diphenoxylate with atropine, for the rapid control of diarrhoea. Dose: 2 tablets 6-hourly.
lomustine A slow-acting cytotoxic agent used in Hodgkin’s disease and solid tumours.
Dose: 130 ing/ni’body surface at intervals of (> 8 weeks. Side-effects, include anorexia. nausea, liver damage and niyelodeprm ion. Dosage should not be repeated until white cell and platelet counts have returned to an acceptable level. Reduced doses are given
when lomustine forms part of a multi-drug dosage scheme. (CCNU). See page 122 and Table 8.
loperamide A synthetic inhibitor of peristalsis.
lorazepam A short-acting anxiolytic/ hypnotic similar to diazepam, but less likely to cause next-day drowsiness. Dose: 1-4 mgdaily. It is also given in similar oral closes or by slow i.v. injection in doses of 50 pglkg for preoperative sedation and anuiesia. Occasionally used i.v. in status epilepticus in doses of 4 nig, but apnoea and hypotension are side-effects that may require resuscitation. fAtivan). See page 152 and Table 22.
lormetazepam A short-acting benzodiazepine hypnotic. It is useful in the treatment of insomnia in the elderly, but is less suitable for insomnia associated with early awakening.
Dose: 500 fig I nig at night. See page 152 and ‘]’able 22.
losartanV An angiotensin 11 receptor antagonist used in the treatment of hypertension.
Dose: 50ing daily The use of potassium-sparing diuretics should be avoided with losartan. It has the advantage of not causing the persistent dry cough associated with ACE inhibitors. (Cozaar). See page 148 and Table 21.
low molecular weight heparins See heparin.
loxapine Antipsychotic agent with the actions and uses of chlorpromazine. Dose: in acute and chronic psychoses, 25-50 mg daily, slowly increased as required. Maintenance doses range from 20-100111g daily. Side-effects are those of other anti-psychotic agents. but loxapine may cause nausea, vomiting and weight changes. f .oxapac). See page 168 and Table 30.
I Mob
magnesium hydroxide A mild antacid laxative, usually given in aqueous suspension as Cream of Magnesia, although tablet forms are also available. Cream of Magnesia is a useful antidote in mineral acid poisoning.
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Lugol’s solution An aqueous solution of iodine 5% and potassium iodide 10%. Used in the preoperative treatment of t hyrotoxicosis.
Dose: 0.3-1 ml.
lymecycline A soluble complex of tetracycline and lysine. It has the action and uses and side-effects of tetracycline, but is absorbed more readily.
Dose: 800 mg daily. (Tetralysal).
typressin An analogue of vasopressin used to control the polyuria of pituitary diabetes insipidus.
Dose: 2.5-10 units several times a day by nasal spray. Side-effects include nausea and abdominal pain. I.ypressin has some vasoconstrictor properties, and desmopressin is sometimes prellcrred. (Syntopressin).
lysuride (lisuride) A bromocriptine-like drug for the treatment of parkinsonism. II acts by stimulating any surviving dopamine receptors in the brain.
Dose: 200 pg at night with food,
irk ceased at weekly intervals according to response up to a maximum of 5 mg daily. Side-effects include nausea, dizziness and initial hypotensive reactions which may affect driving ability. (Revanil). See
page 160 and Table 26.
magnesium sulphate Epsom salts. A powerful saline aperient, producing loose stools by preventing the reabsorption of water.
Dose: 5- 15 g before breakfast. Used externally for the treatment of boils and carbuncles as a paste with glycerin. A marked loss of plasma magnesium may occur after severe diarrhoea or drug-induced diuresis, and may require the i.v. infection of magnesium sulphate in doses based on the degree of hypoinagnesacmia. It has also been given i.v. in a dose of 8 mmol in the emergency treatment of severe;U’rhythinias associated with hypokalaemia.
magnesium trisilicate A white insoluble powder, with mild but prolonged antacid effects. It was formerly widely used in the symptomatic treatment of peptic ulcer;
now used chiefly for dyspepsia.
Dose: 0.3-2 g.
malathion An organophosphorus insecticide. Used as a lotion 0.5% for lice and scabies as alternative to lindane or carbaryl.
mannitol A sugar that is not metabolized, and is used mainly as an osmotic diuretic. Dose: (after a test dose of 200 mg/kg) 50-200 g by slow i.v. infusion over 24 hours. Mannitol has also been used by i.v. infusion as a short-term ocular hypotensive agent in the treatment of glaucoma. It is also useful in cerebral oedema, given by rapid i.v. injection in a dose of I g/kg as a 2044, solution.
macrolides A group of antibiotics that differ chemically from the penicillins, yet have a similar pattern of activity. They are active orally and are useful in the treatment of penicillin-sensitive patients. Erythromycin is the most widely used member of the group, with clarithromycin and azithromycin as more recent introductions.
magnesium carbonate A white, insoluble powder with antacid and laxative properties.
Dose: 0J-4 g daily.
maprotiline A sedative antidepressant with a general action similar to that of the tricyclic drugs represented by amitriptyline. Dose: 25-150 mg daily. If given at night as a single dose, the sedative action may reduce the need for other drugs. It has milder anticholinergic side-effects than some related compounds, although skin rash is more common. (I udionlil). See page 128 and Table 11.
mebendazole An anthelmintic effective against most intestinal worms.

Dose: 100 mg once for threadworm, and 100 mg twice daily for 2 days against other infestations. Generally well tolerated, but it should not be given to children under 2 years of age. (Verniox).
I Men
in oedematous states. A potassium supplement may be required. Care is necessary in renal and hepatic deficiency.
(KiYcaron). See page 148 and Table 21.
mebeverine An antispasmodic agent which, unlike the anticholinergic drugs, appears to have a direct action on the intestinal smooth muscle. It is useful in the treatment of gastrointestinal spasm and in the irritable bowel syndrome. Dose: .100 mg daily, before food. As with other antispasmodics, mebeverine should not be used in paralytic ileus. (Colofac).
medroxyprogesterone A synthetic progestogen.
Dose: in endometriosis 30 mg daily for 90 days; in dysfunctional uterine bleeding and secondary amenorrhoea: 2.3-10 mg daily for 5-10 days, starling on l6th-2 Ist day of cycle and repeated for 2-3 cycles. Large doses of 400 mg-1.5 g daily are given in breast, endometrial, prostate and other hormone-dependent cancers, or 250mg– I g weekly by deep i.m. inJection. (Farlutal; proves). Depot-proves is a long-acting product used by i.m. injection is a contraceptive. but only after fit][ counselling.
megestrol An orally active progestogen. It is used in oestrogen-dependent breast cancer, and acts by suppressing the uptake of oestrogens by the cancer cells.
Dose: 160 mg daily. Nausea and fluid retention with weight gain are occasional side-effects. (Megace). See page 122.
meloxicarn A recently introduced non-steroidal anti-inflammatory drug (NSAID) indicated in the short-term treatment of acute osteo-arthritis and the longer-term treatment of rheumatoid conditions. Dose: 7.5-15 mg once daily with food; half doses for the elderly. Suppositories of 15 mg are also available. The side-effects are basically those of the NSAI Ds in general. Meloxicam has a more selective action on cyclo-oxygenase, the enzyme involved in the biosynthesis of prostaglandins, and is less likely to cause gastrointestinal disturbance, but it has no cytoprotective action, and is not suitable for patients with peptic ulcer. (Niobic). See page 165 and Table 29.
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mefenamic acid A non-steroidal anti-inflammatory analgesic agent used to relieve moderate pain in arthritic and rheumatoid conditions, and other states requiring mild analgesic therapy such as dysmenorrhoea. Dose: 1.5 g daily after food. Side-effects are drowsiness an(] haemolytic anaemia. Diarrhoea is an indication that the drug should be withdrawn. (Ponstan). See page 165 and Table 29.
rnefloquine A drug for the prophylaxis and treatment ofchloroquine-resistant malaria. Dose: lot- short -term prophylaxis 250 mg weekly, starting 1 week before exposure and for 4 weeks after return. Doses for treatment require specialist advice. Side-effects include gastrointestinal disturbances, dizziness and weakness. It is contraindicated in patients with a history of neu ro- psych iatric disturbance, and is not suitable for use in severe renal or hepatic impairment. (Lirium). See halofantrine.
mefruside A diuretic useful in the treatment of hypertension and oedema. Dose: 25-50 mg daily in the morning, according to need and response; 25-100 mg
melphalan An alkylating agent of the mustine type. Used mainly in myelomas, lymphomas and some solid tumours. Dose: 150-300 gg/kg daily for 4-6 days, repeated after 1-2 months. In myeloma it is also given by regional perfusion. The injection solution is highly irritant and contact should be avoided. Side-effects include myelo-depression, nausea, rash and pruritus. (Alkeran). See page 122 and ‘rabic 8.
menadiol A water-soluble form of vitamin K. Dose: 10 ing daily. (Synkavit) Phytorneii,dionc i.% now preferred.
menotrophin Human menopausal gonadotrophin containing follicle-stimulating hormone and luteinizing hormone. It is used in the treatment of anovulatory sterility. The dose depends on individual hormone assays and response. The use of the drug has resulted in multiple births. It is also given to males to stimulate spermatogenesis. (Humegon; Normegon).
menthol Colourless crystals obtained from oil of peppermint. Used as spray or drops for nasopharyngeal inflammation.

A-Z Principal Drugs (ACTH - Allopurinol )

Tuesday, June 23rd, 2009

A-Z Principal Drugs (ACTH - Allopurinol )

ACTH See corticotrophin.

actinomycin D
A cytotoxic antibiotic, also known as dactinomycin, that inhibits cell division by forming a stable complex with DNA. It is used mainly in Wilm’s tumour, and tumours of the
uterus and testes.
Dose: 500 pg daily for 5 days by i.v. infusion, but other dosage schemes are in use. It is highly irritant to soft tissues, and great care must be taken to avoid extravasation.
Close haematological control is necessary. Skin eruptions, alopecia and gastrointestinal disturbances are frequent side-effects. Cosmogen). ‘,cc page 122 and Table 8.

aciclovir (aciclovir)
An antiviral agent highly active against herpes simplex and zoster viruses. It acts indirectly by inhibiting the DNA polymerase essential for viral replication.
Dose: 200 mg 5 times a day for 5 (lays in herpes simplex infections of the skin and mucous membranes, and in genital herpes; in shingles (herpes zoster), 800 mg orally 5 times a
day for 7 days is given, but treatment should be started as soon as possible to obtain the maximum relief of pain. A 5% cream is used for superficial infections, and for herpes
simplex keratitis a 3% ophthalmic ointment is available. Acyclovir is also of’great value in herpes simplex infections in immunocompromised patients. Dose: 200 mg 4 times a day:
800 mg 5 times a day in zoster infections. In severe conditions, 5 mg/kg or more 8-hourly by i.v. infusion. It is also given orally for longterm prophylaxis in such patients.
Reduced doses are necessary in renal impairment and in the elderly. Side-effects include gastrointestinal disturbances, rash and neurological reactions. (Zovirax). See page 144
and Table 19.

adapaleneV
A new retinoid used like tretinoin in the treatment of acne. Applied as a 0.1% gel, once a day, taking care to avoid all mucous surfaces. Irritation may require temporary
withdrawal. (Differin gel).

adenosine
A cardiac drug that slows conduction through the AV node. It is used to restore normal sinus rhythm in paroxysmal tachycardia.
Dose: given by rapid i.v. injection as an initial dose of 3 mg. A second dose of  may be necessary after 1-2 minutes, and a third dose of 12 mg if the tachycardia
remains uncontrolled. For use only with close cardiac monitoring. (Adenocor).

adrenaline (epinephrine)
Adrenaline is one of the principal hormones of the medulla of the adrenal gland, but is now made synthetically. It acts on both the alpha and beta receptors of the sympathetic
nervous system. The effects of the alpha receptors result in vasoconstriction with a rise in blood pressure; stimulation of the beta receptors increases cardiac rate and output,
and relaxes bronchial muscles. Dose: in cardiac arrest, 0.2-0.5 nil of 1 1000 solution by sac. or i.m. injection. In anaphylactic shock and allergic emergencies, 0.5-1 mg (0.5-1
nil of 1:1000 solution) is given by i.m. injection and repeated every 15 minutes as required. An i.v. injection of an antihistamine is sometimes given as supportive therapy.
Doses of 100-200 Vg ( 1-2 nil of 1:10000 solution) have been given by intracardiac injection in cardiac arrest and syncope. In hypotensive crises, noradrenaline or meetaraminol
are preferred. Adrenaline is added to local anaesthetic solutions (1:50000-1:200000) to prolong the anaesthetic effect by reducing diffusion of the anaesthetic solution.
Occasionally the solution is applied locally to stop capillary bleeding and epistaxis. it is also used as eye drops (I I%) in chronic open angle glaucoma, but may cause redness
and smarting of the eye. Solutions of adrenaline may darken on storage and lose activity.

albendazole
An anthelmintic used in hydatid disease with larval cysts of the dog tapeworm. The cysts do not develop into worms, but increase in size to simulate liver abscess.
Dose: given as an adjunct to surgery in doses of 800 mg daily for 28 clays, repeated after a 2-week rest period for 3 cycles, with liver tests and blood counts. (Eskazole).
albumin (human) Human albumin, obtained from pooled human plasma. Given by i.v. infusion as a 5-20% solution in the treatment of shock and other conditions where restoration of
blood volume is urgent; in severe burns to prevent haemoconcentration, and in some conditions of
oalbumaemia, and in acute oedema.

alclometasone

A highly potent topical cortikosteroid. It is used as a 0.05% cream or ointment in inflammatory and pruritic dermatoses likely to respond to such    about 90 seconds after i.v.

alcohol (ethanol)
Used occasionally by injection to destroy nerve tissue in (he treatment of intractable trigeminal neuralgia. Industrial alcohol or methylated spirit contains 5% of wood naphtha;
surgical spirit is industrial alcohol with the addition of methyl salicylate and other substances and is used for skin preparation and the prevention of pressure sores.
Ordinary, coloured, methylated spirit contains pyridine, and is not suitable for medical purposes.

aldesleukin
A recombinant form of interleukin-2, a lymphokinine that stimulates the production of interferon and T-Iymphocytes. Used in metastatic renal cell
carcinoma; severe toxicity is common. (Proleukin).

aldosterone
The main mineralocorticoid hormone of the adrenal cortex. An excessive secretion of aldosterone may occur in some oedematous states and reduce the action of thiazide diuretics.
See spironolactone and canrenoate.

alendronate
A bisphosphonate used in postmenopausal osteoporosis. It inhibits osteoclast activity and increases bone strength, but continuous treatment is necessary. Dose: 10 mg daily in
the morning with water on an empty stomach, 30 minutes before food. Side-effects include severe oesophageal reactions. (Fosomax).

alfacalcidol
A derivative of calciferol, with a more powerful and rapid action. It is used to treat hypocalcaemia in hypoparathyroidism, neonatal hypocalcaemia and other hypocalcaemic
states, and in vitamin D-resistant conditions. Regular blood calcium determinations are
essential as a drug-induced hypercalcaemia percalcaemia may take weeks to subside after
withdrawal.
Dose: 1 mg orally or i.v. daily initially, according to response. (,Alpha 1); OneAlphal.

alfentanil
A potent, rapidly acting narcotic analgesic, useful in short surgical procedures, or for longer operations in ventilated patients. The peak effect occurs

alfuzosin

A selective alpha-adrenoceptor blocking agent for the symptomatic treatment of benign prostatic hypertrophy (BPH).Dose: a first dose of 2.5 mg should be given in bed to avoid a marked first-dose hypotensive response, then 7.5 mg daily. Side-effects are dizziness, hypotension and
tachycardia. (Xatral). See page 164 and Table 28.

alglucerase

An enzyme product used i.v. by specialists in Gaucher’s disease. (Ceredase).

alkylating agents
Cytotoxic drugs which act by damaging DNA, and so interfere with cell replication. Chlorambucil and cyclophosphamide are examples.

allantonin
A natural substance said to promote wound healing. Present in some locally applied products for skin disorders.

allergen vaccines
Weak allergen vaccines prepared from allergens such as grass pollens, house dust mites and bee stings are used to desensitize hypersensitive individuals but such treatment
carries the risk of severe anaphylactic reactions, which may prove fatal in asthmatics, and it is now recommended that desensitization therapy should be carried out only when
full cardiorespiratory resuscitation
measures are immediately available.

allopurinol

An enzyme inhibitor that blocks the formation of uric acid, and so is useful in the treatment of chronic gout. It also reduces the formation of uric acid calculi. It is usefulin the hyperuricaemia of leukaemia but it should be given before cytotoxic therapy is commenced.Dose: 100 mg daily as a single dose with food, slowly increased to 300 mg daily or more as required, reduced in cases of renal impairment. It may cause gouty arthritisinitially, requiring colchicine or non-steroidal anti-inflammatory agent (NSAID) treatment for at least I month. Side-effects include nausea, headache and gastrointestinal
disturbances, but skin reactions indicate withdrawal of the drug. (Zyloric). See page 140 and Table 17.

Allergy and Children

Friday, May 22nd, 2009

Suffering from a long-term illness, especially if it is severe and sometimes limits activity, can easily make a child feel different from other children, and ‘not good enough’. Children with allergies, especially those with severe asthma or food allergies, may also be very frightened and anxious. At the same time, such children often feel that they have to protect their parents by not revealing their fears.
Children may also think that their illness is a punishment for something they have done wrong. Their guilty feelings can be so powerful that they may not confide in you unless you spend time talking with them about their illness, and encourage them to share their feelings with you.
One of the most valuable things you can do for children with allergies is to build up their self-esteem. This is especially important when they first start school, because they have to adjust to other children there, and learn how to deal with questions about their illness, as well as some unkindness.
For children whose allergies limit what they can do physically, or restrict some normal activities, try to find other interests and hobbies that the child can do well. When talking with the child, always emphasise the positive things – the difficulties that you have overcome together in the past, the measures that the child can take to keep the symptoms under control (such as stopping scratching, applying creams, or using a preventer inhaler) and the areas of Iife where he or she is particularly successful. As the child gets older, introduce the idea that coping with illness makes you a stronger, kinder and more resolute person, one who can cope with any of life’s challenges. Show the child how much you value their maturity and perseverance.
Pay attention to what the child’s friends are
saying – a bit of eavesdropping is allowed – and be prepared to counteract any negative messages. Teach your child to be strong and self-confident about choosing their friends, and to prefer those who are sensible, understanding and supportive. Ask casually about what schoolteachers and other adults say when you are not around, because they can, without meaning any harm, undermine a child’s confidence with thoughtless remarks.
For children with problems that are potentially life-threatening, such as true food allergy, your natural anxieties as a parent can lead you to be overprotective. This can make the child feel smothered, but letting go is far from easy. You somehow have to find a middle path that works for you both.
With asthmatic children, focus on letting them live as normal a life as possible. Avoid saying ‘no’ automatically to things that might induce an asthma attack – such as running around outdoors in cold weather. Take some small risks, and let the child make the decision sometimes – he or she will gain a lot from taking the responsibility, especially if the decision is the wrong one.
This is the only way for children to learn how to manage their own condition. The sooner you can begin letting go, the better the child will cope in his or her teenage years, when it really will be necessary to make some difficult decisions without your help.
A pitfall for parents
In bringing up a child with allergies, remember that there should never be any ’secondary gain’ from illness – absolutely no advantages to having the eczema get worse (easily done by scratching) or starting an asthma attack (some children can bring one on by breathing in a particular way).
If your child has to take time off from school because of ill-health, ask the teacher for work that can be done at home, and check that it really is done. Children who are allowed to benefit from being ill can establish an unhealthy pattern for dealing with life’s difficulties (see pp. 94-5), which may be long-lasting. Such a mind-set can seriously limit a child’s development.
Incidentally, the ’secondary gain’ from illness may be quite altruistic in nature. It can include stopping parents from arguing, or from nagging a naughty brother or sister, as well as more obvious things such as getting a parent’s attention – so be aware of all the circumstances in the family that are affecting the child.
Sometimes a child realises, unconsciously, that attending to illness gives a parent welcome distractions from emotional problems and a comforting feeling of being needed and useful. The allergies can become part of the structure of a family, the glue holding everyone together.
Conversely, long-term illness can tear families apart: according to recent research carried out in the United States, divorce is more common in families where a child suffers from severe asthma.
Doctors frequently notice that severe eczema also can create a lot of tension in the home.
If you feel that a child’s illness is affecting the family badly – in whatever way – talk to your doctor, or someone else who you trust. You may need the help of a counsellor or family therapist to sort things out.
Children and medicines
Parents often feel very anxious about all the medication an allergic child uses. On the whole, the drugs prescribed for allergy are very safe, and only children with severe disease are at risk of significant side effects. These children will be carefully monitored by the doctor.
Needless to say, if you can cut down on the drugs by reducing allergen exposure, avoiding irritants (e.g. tobacco smoke) and implementing some of the other measures described in this book, you should do so. But if the child still needs drugs to control the symptoms, it is far better to accept them than to let the child struggle with all the discomfort, limitations and distress that the illness imposes.
Parents who are very concerned about drugs should talk openly to the doctor about their fears. If there are differences of opinion about drugs within the family, try not to expose the child to the disagreements. Sort out a joint policy in advance and always present a united front to the child. Be consistent and reassuring about drug use, otherwise the child may feel confused and anxious about the situation – or may even learn to manipulate it.
The asthmatic child
Children with asthma should have a management plan (see p. 96) and may benefit from using a peak-flow meter (see p. 97). Once your child is old enough to comprehend the difference between preventers and relievers, explain that using the preventer regularly keeps asthma under control, which means no sudden attacks and less need to use the reliever in public — something which most children find intensely embarrassing. You should oversee the child’s treatment closely until the age of seven or eight, then gradually let the child take over some of the responsibilities.
Coping with food allergy
The following concerns true food allergy (see p. 62), which can be life-threatening, not idiopathic food intolerance (see p. 74).
Protecting a child with severe food allergies is a major task. You will find it enormously helpful to be in contact with other parents who are facing the same challenge. The practical details are everything here, and you can benefit from other people’s ingenuity in solving day-to-day problems. Several support groups exist (see p. 255), offering a wealth of advice.
For very small children, the main task is to ensure that everyone who looks after the child understands exactly what can and can’t be eaten. Child-minders and baby-sitters should spend time with you as ‘apprentices’ seeing what is involved in preparing food for the child – this is far better than just giving verbal instructions. Also make sure that everyone knows how to use the adrenaline auto-injector (see pp. 98-9).
Once children start going to parties, you should always stay at the party for the whole time, and supervise your child closely. Take food that your child can safely eat, but which other children can also share. Some parents put a label on toddlers warning other adults that certain foods are taboo – for children under reading age this is probably acceptable, and does allow you to relax a little, but with older children the dangers of being teased or stigmatised should always be borne in mind.
Plan ahead all the time. Keep a snack box in the car containing food that the child can safely eat. Whenever you go on a trip, however short, have some safe foods with you, in case you get stuck somewhere and the child gets hungry. If you go out to eat, exert maximum caution about the restaurant food (see p. 111). Some parents take along a guaranteed-safe, but super-delicious sandwich or burger, and ask the restaurant to warm it up in a microwave (where appropriate) and serve it at the same time as the other food. If you do this, be sure the staff understand that the food must not touch any other food.
At home, some parents opt for everyone eating the same allergen-free food, on the basis that this makes for being ‘a real family’. Others, finding this too problematic or expensive, make a virtue out of the allergic child having a different meal. ‘I try to make her feel special about having her own food. The allergen-free dinner or cake always looks and tastes really good.’
As children get older, and more independent, you need to educate them thoroughly about avoiding the offending food. Equip them for difficult situations by role-playing. Act out being offered a tempting item of food by another child, and being jeered at for refusing. Act out suffering an allergic reaction to food and getting help quickly, even though people around don’t understand and are uncooperative.
Allergies and schools
When your child starts at a new school, creche, or kindergarten, request a meeting with staff and teachers to talk about the child’s allergies if there is any likelihood of these becoming a problem. Do this well before your child starts at the school, so that any necessary changes can be made. If your child has a serious food allergy or severe asthma, you may have to make several visits because there are usually a number of different people you should meet, and follow-up sessions may be needed with some staff. If all this sounds daunting and ‘not my style’ then you need, for the sake of your child, to develop your skills in dealing with people and being assertive. Talk to a counsellor, or look for suitable training courses.
In addition to ensuring that the school takes good care of your child’s health (see below), you should also discuss wider issues of adjustment to school life. Teasing or bullying can be a problem for children with any kind of health problem. Ask the teacher to keep an eye on your child and ensure that he or she is coping well – for example, that there is no difficulty about using an inhaler in front of other children when necessary.
Eczema
Ensure all staff realise that the skin rash is not infectious, and that they are aware of the need to communicate this to other children. The appearance of the skin can create a lot of problems with class-mates, and teachers need to be alert for taunting remarks or hurtful nicknames.
Unfortunately, children with eczema are very susceptible to infections caught from others, such as impetigo (see p. 44), but you can’t really protect children from such infections without isolating them socially. The best way to tackle this problem is to deploy all the available treatments so that your child’s skin becomes stronger and more resistant.
Food allergy
If your child has food allergy, go and see the catering manager personally. It may be helpful to take some printed material on food allergy with you, plus lists of synonyms for food ingredients (see pp. 172-4) where appropriate. Concentrate on building up a good relationship with catering staff, while ensuring that they understand how dangerous certain foods can be to your child.
Many parents feel more relaxed if they supply their child with a packed lunch that they know is allergen-free. This is often a good strategy, but don’t be complacent. Most allergic reactions in schools involve food given or traded by another child with entirely good intentions. Some schools with food-allergic children have set up a ‘no trading food’ policy, which seems to work well. Other schools establish milk-free or nut-free tables in the canteen, so that friends can sit together and trade food safely. (The mothers of the other children sitting at these tables need to be well versed in food avoidance, of course, so that their packed lunches are as safe as your own.) In the United States, schools have sometimes tried banning nuts or peanuts altogether, where there is a nut-allergic student, but this does not work well.
Some parents prepare a printed information sheet about their child’s food allergy, with a photograph of the child, and put these up at strategic points around the kitchen and canteen area. This information can include instructions on how to deal with anaphylactic shock (see below) and who to contact in an emergency.
Finally, include the art teacher in your rounds – foodstuffs are often used in art and craft projects.
Anaphylaxis
For children with severe food or insect-sting allergies which can lead to anaphylaxis, check that everyone at the school understands the potentially fatal nature of this condition. Key staff must know how to recognise anaphylactic shock and exactly what to do: show them how the adrenaline injector kit works. You could take along an old one, so that they can practise (see p. 150). Injector kits and adrenaline inhalers must be within easy reach, never locked in a cupboard.
Repeat this educational process at the beginning of each new school year, and before school trips. As an additional precaution, your child should wear a bracelet or pendant (see box on p. 95) that informs medical personnel about his or her allergies –this is also vital for children with latex or drugs allergies.
Asthma
If your child has asthma, ask what arrangements are made for inhalers. Children who can take responsibility for their own treatment should keep their inhalers with them. For younger children, the inhaler should be in the classroom, somewhere that is easily accessible (never locked away) and should be taken along during breaks and mealtimes. The child must always be able to get to the inhaler quickly: even a small delay in using it when an attack occurs can have dire consequences. Make sure everyone at the school understands this, that they know how to recognise an attack, and how to react. Assure the teacher that there is little danger of an asthmatic child overdosing, and if other children take a few puffs they will come to no harm.
If the teacher seems to believe that asthma is a psychological problem (some still do), go and see the head. Suggest that a local asthma nurse or doctor comes in and talks to the staff and pupils about asthma.
Ensure that the teacher knows about the effects of cold air and exercise on asthmatics. Talk to the games teacher or sports coach, and the playground attendants. It is vital that the games teacher is encouraging but understanding towards asthmatic children. They should never be told to continue exercising if they feel breathless.
Allergens and irritants in school
Schools today often have soft furnishings and carpets – these may be full of dust mites. If your child is allergic to mites, and if allergy symptoms are frequent at school, have a look around the classroom and see if this might be the cause. Before discussing the problem with the school, learn all you can about dust mites (see p. 114-117) so that you can assess whether proposed solutions to the problem would actually work.
Pets are common in classrooms and they can cause allergic reactions in sensitised children. Moulds flourish in many school buildings, and will affect a child with mould allergy. Poor ventilation is sometimes a major problem in school buildings, especially those where windows cannot be opened.
Irritants in school air include glue, paint, the solvents from felt-tip pens, disinfectants, air fresheners and the fumes produced during science lessons. Make sure the science teacher is aware of the risks and always uses a fume cupboard if irritant gases such as nitrogen dioxide or sulphur dioxide are likely to be given off during an experiment.
Applying sunscreens to children’s skin is now routine in many schools and preschools. Teachers probably won’t think to ask permission, so if your child is sensitive to any common ingredients of creams or sunscreens, let them know in advance.

Dealing with Emergency in Allergy

Thursday, May 21st, 2009

Let’s hope it never happens - but if it does, knowing what to do could make the difference between surviving and not surviving. The sensible thing is to read these pages - or whichever parts are relevant to you or your child - before you encounter an emergency. It is often helpful to rehearse the procedure in your mind and actually imagine yourself going through the actions described here.
Find out in advance what the local ambulance service is like, and ask your GP for advice about who to contact in an emergency. (If you have latex allergy, check in advance that all local ambulances carry a latex-free kit.) These are the options:
• Call your GP.If the doctor is nearby and the hospital or ambulance station a long way off, this may be the best decision. Doctors in rural areas may have supplies of adrenaline for emergency treatment, and oxygen for those suffering a severe asthma attack.
• Call an ambulance. Where the local ambulance service is dependable, this is always the best option. The ambulance crew will have adrenaline and oxygen.
• Go by car or taxi to the nearest hospital
emergency department. This is not usually a
good plan, because your condition may quick-
ly get worse, and you have no emergency
treatment available. But there may be situa-
tions where it is a sensible decision. Emergencies can occur when you are away on holiday or business. Never stay anywhere without a phone – check that it is working as soon as you arrive. Make sure you have the number of a local doctor and know where the nearest hospital is. A remote holiday cottage can be a dangerous place to suffer an asthma attack or anaphylactic shock.
Anaphylactic shock
This is an extremely serious emergency, requiring immediate medical help. The signs of anaphylactic shock are listed on p.58. In the case of food allergy, there are additional signs in the mouth, lips and throat (see p. 62). Use adrenaline (epinephrine) straight away if you have it – but get emergency medical help as well. With injectable adrenaline (an EpiPen or Anapen – see p. 150), remove the cap and jab firmly into the outer thigh, going straight through any clothing. Never inject into any other part of the body – this can be dangerous.
If you have an adrenaline inhaler (see pp. 155-6) you can use this first to treat symptoms in the mouth, throat and airways, and then use the injector if you still have symptoms. (Improvise a spacer – see p. 100 – if there is difficulty in inhaling the adrenaline.) Anyone whose reactions tend to be severe should use the injector first and follow up with the inhaler if necessary. Overdosing with adrenaline is possible, and can be fatal, but using the inhaler as well as the injector is safe as long as you don’t have a heart condition (see pp. 155-6).
If you do not improve after using the injector, a second one can be used, 10-15 minutes later.
In situations where medical help is not yet available and the symptoms are not abating, another shot of adrenaline can be given every 15-20 minutes. But the maximum number of shots recommended by your doctor should never be exceeded. Keep count of how many you’ve had, and tell medical staff.
An asthmatic who does not have an adrenaline inhaler can use a beta-2 reliever inhaler such as Ventolin (see p. 152) as well as the adrenaline injection, although it probably won’t help very much.
Suppose you know for sure that you have encountered your allergen, but you don’t have any symptoms yet? In Britain, the usual advice is to wait for symptoms, but doctors in the United States say go ahead and use the adrenaline injector if you have reacted very badly in the past. In general, for people with no other health problems, it is better to give an adrenaline injection which isn’t needed than to delay giving one that is needed. Delaying the use of the injector may mean that the reaction gets out of control. Some people put off using the injector because they think it should be saved for when they ‘really need it’. In fact the adrenaline works just as well if you have used it on previous occasions.
Following anaphylactic shock, you should be kept in hospital for 6-12 hours even when everything seems fine. Attacks have recurred as much as eight hours later. Corticosteroids reduce the chance of this happening – ask if these have been given. If you are discharged early and it is a long journey home, consider waiting in the hospital, or nearby, until eight hours after the original reaction.
First aid for anaphylactic shock
A badly swollen tongue or throat can cause suffocation. If there is visible swelling and the person is unconscious or turning blue, try to keep the top of the trachea (the main airway leading from the throat) open. Use the handle of a spoon – one that has very smooth edges. Slide it carefully over the top of the tongue and into the throat. Press down gently but firmly to open the airway.
Someone who is feeling faint or dizzy, or losing consciousness, or (in the case of a child) becoming very pale and floppy, may be suffering from a dangerous drop in blood pressure. He or she is more at risk of a fatal collapse if in an upright position, because not enough blood is reaching the heart. The worst thing is to stand up suddenly, or to move (or be moved) quickly from a lying to a sitting position –death can follow within seconds. The best thing is to lie down, preferably with the legs resting on cushions or a stool so that they are above the torso, and with the arms raised above the chest. Adrenaline can be given while in this position. A stretcher should be used to get the patient to an ambulance.
Latex allergy and emergency treatment
If you have anaphylaxis due to latex allergy, going to hospital can be alarming, as you may suffer further reactions to latex gloves or equipment. Some patients with latex allergy have had such bad experiences in ambulances and hospitals that they become fearful of using their adrenaline injector, since this means they must go to the hospital afterwards. They delay using the injector, which makes the situation worse. Some doctors are now giving such patients all the medicines and training they need to manage their anaphylactic shock themselves, so that they don’t need to attend hospital.
A person who has lost consciousness should be lying down on their side in case they are sick (this reduces the chance of them inhaling their vomit). The same goes for anyone who feels nauseous.
On the other hand, if the major problem at the outset is difficulty in breathing (as it generally is in children) a sitting position is better.
It is unusual for both faintness and severe breathing problems to be present at once. If this occurs, the patient should lie down, and if there is swelling in the throat, a spoon should be used (see left) to keep the airways open.
Insect-sting allergy
If you don’t have an adrenaline injector, get medical help immediately.
If you’ve had a cutaneous systemic reaction (see p. 60) in the past, use the adrenaline injector if there is any difficulty in breathing, hoarseness, stomach cramps, diarrhoea, nausea, faintness, dizziness or confusion. If you are unsure, remember that, unless you have a heart condition, it is usually better to overreact (i.e. use the adrenaline unnecessarily) than under-react.
If you’ve had a severe systemic reaction (i.e. anaphylactic shock) in the past, use an adrenaline injector at the first sign of any reaction other than immediately around the sting.
If there is a honeybee stinger left in the skin, scrape or flick it out sideways using a fingernail, knife blade or credit card – the venom sac is attached and will go on injecting venom for up to 10 minutes if you leave it there.
Don’t try to pull the stinger out – this squeezes the venom sac and pumps more venom into the skin.
Get emergency medical help, and follow the other measures for dealing with anaphylactic shock (see left).
Don’t go alone
If you suffer vomiting or diarrhoea during anaphylaxis, and have to go to the toilet, tell someone to call an ambulance and take someone else with youto the toilet. Do not go in alone and lock the door, in case you collapse.
Asthma attacks
Even those with mild asthma, who have never had a serious attack before, can quite suddenly get into difficulties and require emergency treatment. Don’t be over-anxious about this, because it is unlikely to happen – but do be prepared. Not having your reliever inhaler with you when a severe attack starts is a recipe for disaster – always take it, wherever you go.
Deal with an attack promptly. The sooner you act, the fewer drugs you’ll need in the long run to control the attack. Most asthmatics wait too long and then under-treat their asthma.
The important thing is recognising an asthma attack, and knowing when it is getting out of control. Not all attacks are the same – some come on fast, some come on slowly.
Rapid asthma attacks come on in a matter of hours. You may have been fine all day, but then start to feel very breathless and wheezy, or begin coughing badly. Less than an hour later, despite using the reliever, the breathlessness is worse and it is a struggle to speak or walk across the room. This is a severe attack: don’t delay in getting medical help.
Slow asthma attacks come on over a period of days. At first you are more breathless and wheezy than usual, and your reliever inhaler is not helping much. Asthma wakes you up at night, and you are far more breathless than usual in the morning. This could be the beginning of a severe attack, so don’t delay in getting medical help. If you get to the point where your asthma is disturbing your sleep every night, and in the morning you have difficulty in speaking or walking about, this is a very serious situation – you must see your doctor or go to the hospital now.
A few asthmatics have great difficulty recognising when they are increasingly breathless, and for them, using a peak-flow meter (see p. 97) every day is essential. Indeed, most asthmatics find
Recognising an asthma attack in a very young child
With a young child, these signs indicate a severe asthma attack:
• the nostrils are flared
• the shoulders are unusually high
• the child can say only one or two words between breaths
• the ribs are pushed out, and the spaces between the ribs, and below the chest cage, are sucked in during breathing
• you can hear wheezing (a whistling noise)
• the lips, tongue or fingernails are blue.
If wheezing stops, without any other apparent improvement, this is a very bad sign — it may mean that the airways are now so narrow that no air is passing through them. This is called a ’silent chest’, and indicates an urgent need for medical attention.
that monitoring peak flow is a valuable way of spotting attacks in advance. However, if your peak flow seems normal, and yet you feel breathless and have a tight feeling in your chest, pay attention to your symptoms and get medical help.
Your response to your reliever inhaler is another helpful sign assessing asthma attacks. Things are serious if:
• the reliever inhaler does not seem to be working at all within 10 minutes of taking a puff
• it does not work as well as usual
• it works, but the effect wears off in less than three hours. If you have an asthmatic child, give everyone who normally takes care of the child detailed written instructions for recognising and dealing with an asthma attack. People forget verbal instructions especially in an emergency. A child who is exhausted or upset c. an attack should always be given medical care.
Taking action
If your reliever inhaler is not working well (see above), take another puff to open up your airways – and then take further action. as described below.
If you seem to be in the early stages of a slow asthma attack check your management plan, and if your peak flow has fallen below the recommended level, double the dose of inhaled steroids (twice as many puffs each time) now. Add any other medicines (e.g. steroid tablets) as recommended by the management plan.
Those who don’t have a peak-flow meter or management plan should double the dose of inhaled steroids and make an urgent appointment to see the doctor.
If you are suffering a rapid attack, or a slow attack that has got out of control, you need emergency medical help. Ring for an ambulance, ring your doctor, or go to the hospital – the ideal course of action will vary, depending on where you live (see p. 98).
Use your reliever inhaler until medical help arrives. You can take a puff every 5-10 minutes if needed, but keep a count of how many puffs you’ve had and stop after 30. Some doctors suggest taking up to 30 puffs all at once. (If you have a heart condition, this dose might be dangerous: follow your doctor’s advice.)
If it is difficult to inhale, use a spacer – this can make all the difference, especially for children.
You can improvise a spacer from a plastic cup, a plastic bottle, or a paper bag. Make a hole in the bottom of the cup or bottle, or in one corner of the paper bag, and insert the mouthpiece of the inhaler here. The open end of the cup, bottle or bag goes in or over the mouth – with the bag, you have to bunch it up and hold it around the mouth. Squirt the inhaler repeatedly into the improvised spacer, while breathing steadily in and out.
The six golden rules for asthma attacks
• Breathe as slowly as possible and concentrate on breathing out, not on breathing in. Exhale as fully as you can and your in-breath will follow automatically.
• Never panic – if you do, you may start hyperventilating, and this makes matters much worse (see p. 226). Panicky parents are the worst possible thing for an asthmatic child during an attack.
• Adopt a position that makes breathing as easy as possible. Propping your arms up at about shoulder height can help – for example, sit back-to-front on a dining chair, with your arms folded and resting on the back. Or put pillows on a table, sit in an upright chair, and rest your head and arms on the pillows. Don’t lie down, as this makes matters worse. Open a window, as long as the air outside is not cold, polluted or loaded with pollen.
• Avoid factors that can make an asthma attack worse, for example, vigorous activity, cold air, irritants and allergens.
• Drink plenty of water, fruit juice or other liquids as a lot of water is lost through the surface of the airways during an asthma attack, and you can become dehydrated.
• Don’t take anything to help you sleep, even herbal pills. If your asthma gets worse during the night, you need to wake up so that you can get more air.
After an attack
Asthmatics who have suffered a severe attack are occasionally sent home from hospital before they are completely better. A few people have died as a result of being discharged too soon. So if you feel breathless or otherwise unwell after you leave hospital, don’t hesitate to go back – or seek other medical help.
See your GP or specialist within a few days of any emergency treatment. Don’t be over-confident just after a severe attack – this can be a very vulnerable time. Take more rest than usual and drink plenty of fluids, as you may be dehydrated. Keep taking your preventer inhaler at the increased dose – reducing the dose now could lead to another severe, possibly fatal, attack. Keep taking steroid tablets if you have been given them.
If you produced a lot of mucus during the attack, try to clear it, but without violent coughing. Mucus can sometimes form solid plugs which block small airways. Treatment by a physiotherapist would help, and expectorants – drugs which help loosen mucus –can also be useful (ask your pharmacist about these). Don’t take ordinary cough medicine (see box on p. 163). There are also some breathing exercises which can help to clear mucus (see p. 231).
An asthma attack represents a chance to learn more about preventing asthma – so think about what went wrong. Had you forgotten to take your preventer inhaler regularly? How long is it since you had your medicines reviewed by the doctor or asthma clinic? Have you been using your peak-flow meter daily? Were you exposed to a high dose of allergen or an irritant?
A reaction to aspirin-like drugs
Aspirin sensitivity can begin quite suddenly in someone who has previously taken aspirin without trouble. If you have unexplained chronic urticaria, or polyps in the nose, plus asthma and/or rhinitis, the development of aspirin sensitivity at some time in the future is a distinct possibility (see p. 151).
A sensitivity reaction to aspirin or aspirin-like drugs usually begins between 30 minutes and two hours after the drug is taken. You will have some or all of these symptoms:
• a runny or badly blocked nose, and red eyes
• a feeling of warmth, flushing and sweating
• a general rash
• a sensation of tightness in the chest, a dry cough, increasing breathlessness
• malaise and exhaustion
• vomiting or diarrhoea
• swelling (angioedema) and/or nettle rash (urticaria). If you have such symptoms get emergency medical help immediately because the reaction can quickly develop into severe asthma, shock, collapse and unconsciousness.
If you have asthma, use your reliever inhaler as much as required (up to 30 puffs) until medical help arrives. Anyone who has an adrenaline (epinephrine) auto-injector, or an adrenaline inhaler, can use this as well – up to 30 puffs of the inhaler, or whatever maximum dose is given in the instructions. Tell the ambulance crew and doctors exactly what you have taken.

Allergies and Pregnancy

Thursday, May 21st, 2009

Allergies and Pregnancy
Great care is taken in prescribing drugs during pregnancy. This is something that doctors are now exceedingly cautious about, but do tell the doctor as soon as you decide to try for a baby. The foetus is most vulnerable to damage by drugs during the first three months, and especially the first few weeks after conception.
Your prescription will be changed if the drugs you are currently taking could pose any threat to the unborn child. A drug that has not had sufficiently rigorous testing for safety during pregnancy, or lacks a long track record, will probably be withdrawn. New drugs are generally considered to be slightly more risky than the tried-and-true older drugs: rare side effects may not come to light during the testing which precedes release of a drug, but they do become apparent once the drug is in widespread use for a long time (see pp. 136-7).
If you are already pregnant as you read this, don’t worry too much. With a few notable exceptions – certain antihistamines and antibiotics – most of the drugs used for allergic diseases do not pose any major risk to the unborn child. There is probably nothing to worry about, but see your doctor as soon as you can – and talk to a pharmacist, in the meantime, if you are concerned. Don’t panic, and don’t stop taking your drugs unless you are absolutely sure that you can do without them. Do not stop taking your drugs if you have asthma.
Some non-prescription medicines are best avoided during pregnancy. Read the packet carefully, and talk to your pharmacist if you have any doubts.
From the moment you start trying for a baby, remember to tell any medical personnel who treat you, and any pharmacist you buy medicines from, that you could be pregnant.
Immunotherapy and skin testing
Immunotherapy should not begin during pregnancy, because of the risk of anaphylaxis (see below), but pregnant women who are already undergoing immunotherapy can continue.
The safety procedures described on p. 166-7 should be followed with meticulous care.
Most doctors continue immunotherapy at a steady ‘maintenance dose’ because there is always a small risk of anaphylaxis with immunotherapy when the dose is increased. Some doctors are even more cautious and reduce the maintenance dose during pregnancy, but give more frequent injections – this minimises the chance of bad reactions.
Many doctors do not give skin tests for allergy during pregnancy, as these also carry a very small risk of anaphylaxis. If you do have skin tests, there must be resuscitation equipment available. Intradermal tests (see p. 92) are best avoided.
Severe allergic reactions (anaphylaxis)
Special care should be taken to avoid anaphylaxis during pregnancy as this may increase the chance of a miscarriage.
Injecting adrenaline during the first three months of pregnancy may carry some small risk of malformation of the baby. But the evidence here is uncertain, whereas the danger to your own life, if you don’t use adrenaline when you need it, is both certain and substantial. If you have an adrenaline self-injection kit, talk to your doctor now about what you should do in an emergency. The best policy is to be ultra-careful about avoiding your allergen, so that anaphylaxis does not happen.
Women who suffer from exercise-induced anaphylaxis (see p. 59) generally play safe by exercising less strenuously while pregnant. The problem can get worse during pregnancy, but it does not usually do so. Labour itself is very strenuous of course, but problems during the birth are uncommon. If anaphylaxis does occur, the reaction is usually quite mild – nettle rash only – and the baby is delivered alive and well. However, many women find that the attacks of exercise-induced anaphylaxis are more frequent and severe when they start exercising again after the baby is born. It is best to resume exercise very gradually.
Eczema and other skin problems
Atopic eczema may improve during pregnancy, probably because the body produces slightly more of its own natural steroid, hydrocortisone. Contact dermatitis may either improve or flare up.
Stretch marks often itch a great deal, and widespread itchy skin, with or without a rash, is a common problem during pregnancy. These are not usually allergic reactions, and no cause can be identified in most cases. The skin tends to recover a few days after the birth.
If there is itching in the vulva) area, this could be due to a Candida infection (your doctor can prescribe a safe treatment) or it might be just another of those unexplained itches of pregnancy.
Hayfever and other nasal allergies
The natural hormone changes of pregnancy affect the nose, which can become more blocked. If you have allergic rhinitis this will add to your woes. See your doctor and make sure that your drug treatment is adequate (see p. 29). The nose-clearing exercises on pp. 230-31 might also help.
Asthma
Severe asthma can be bad for both the pregnant mother and the unborn child. Uncontrolled asthma increases the risk of the baby being born prematurely – and premature babies are more likely to develop asthma themselves. The death rate for newborn babies is also higher if the mother has poorly controlled asthma.
Treating a severe asthma attack promptly helps to prevent any damage to the baby, so don’t hesitate to call an ambulance –and tell the operator you are pregnant. The ambulance should be carrying oxygen which is particularly important for helping the unborn baby through the attack.
If you have asthma, don’t stop using your drugs or reduce the dose unless advised to do so by a doctor. Because it is so important to keep asthma under control during pregnancy, your doctor may want to add, or increase, preventer drugs such as inhaled corticosteroids or sodium cromoglycate (see p. 148). It
also makes sense to monitor your peak flow twice a day (see p. 97) so that you have advance warning of serious attacks.
Unfortunately, some asthmatics – usually those who have severe asthma to begin with – get much worse during their pregnancy. In such cases, careful monitoring and increased use of preventer medicines are essential. The symptoms usually increase from week 24 to week 36 of the pregnancy. The last four weeks tend to be much better, and things are back to normal by about three months after the birth.
Some women with asthma have fewer symptoms while they are pregnant, and for others their asthma stays about the same.
Asthma can also appear for the first time during pregnancy, and may be quite severe. However, a relatively mild breathlessness can be due simply to the fact that, as the pregnancy advances, the chest cavity, and therefore the lungs, become compressed. This is not necessarily asthma.
This simple physical effect can also add to the difficulties experienced by women who were already asthmatic before they became pregnant.
GER (acid reflux) – see p. 38 – can contribute to asthma during pregnancy, and treating this problem may help.
Asthma attacks during the birth
Severe asthma attacks very rarely occur during labour, but it is still important that all the medical staff in attendance know you have asthma. They should also be told if you have taken steroid tablets during the previous two years. A record of when you took steroids, how long for, and at what dose, will be valuable. You may need a low dose of steroid to get you through the physical stress of labour (see p. 142). Some doctors believe that patients who have been using high-dose inhaled steroids should be treated in the same way.
Smoking
Smoking is a bad idea if you have allergies or any allergic tendency in the family. Smoking is a very bad idea indeed if you are pregnant, or a parent. This is the moment, if ever there was one, to give up.
Enlist your doctor’s help, and ask if counselling, psychotherapy or other forms of support are available. If you have tried all this before, and failed, then talk to your doctor about the possibility of using nicotine patches. Some doctors believe that, for pregnant women who smoke 20 cigarettes or more a day, the advantages of nicotine patches outweigh the risks to the foetus. Nicotine levels in the blood are lower with patches than with heavy smoking, and your baby is not enduring the hundreds of other toxins found in cigarette smoke.

Various Anti-Allergy Drugs

Tuesday, May 19th, 2009

Various anti-allergy drugs
An allergic reaction is a lengthy, complex process, and the various anti-allergy drugs all work on different stages of that process. That is why it often makes sense to use several different drugs for the same allergic condition: they each tackle the problem in their own way.
Steroids (see p. 140) intervene at a very late stage, quelling the inflammation that follows on from an allergic reaction. Using a steroid is rather like calling the fire brigade to put out a fire, whereas using an antihistamine (see p. 138) is like having fire-proof doors, to prevent the fire spreading at an early stage. Cromoglycate-type drugs (see below) intervene at an even earlier stage. They are like basic fire prevention - teaching children not to play with matches, or fitting smoke detectors.
Anti - leukotnene drugs (see p. 149) work at roughly the same stage of the process as anti-histamines but tackle an entirely different aspect of the allergic reaction.
Cromoglycate-type drugs
These drugs are also referred to as mast-cell stabilisers or mast-cell Mockers.
There are three drugs in this group, sodium cromoglycate (also spelled cromoglicate), nedocromil sodium, and lodoxamide. All operate at an early stage of the allergic reaction, stopping it before it actually starts. They stabilise the outer membrane of the mast cells (see box on p. 12), which prevents the allergic response from occurring.
Some common brand names
Common brand names of cromoglycate-type drugs include:
inhalers - Cromogen Easi-Breathe, Intal, Tilade
eye drops - Hay-Crom, Opticrom, Rapitil, Vividrin, Viz-on nose sprays - Rynacrom, Vividrin
capsules - Nalcrom
This is a far more satisfactory way of dealing with an allergic reaction than trying to tackle it after the reaction has occurred. But from a purely practical point of view, it has a drawback. I order to work at all, these drugs must reach the mast cells in advance of the allergen. They are of very little use if taken after the allergic reaction has begun.
For those who are taking cromoglycate-type drugs on a regular schedule, several times a day, it is very important to be conscientious about taking them on time. This maintains the protective effect of the drug, without any gaps.
If you are using these drugs on an ‘as-needed’ basis, you should take them 30 minutes before an allergen is encountered. or 30 minutes before a bout of exercise, if they are being prescribed for exercise-induced asthma. (Note that children sometimes respond differently, getting protection from these drugs immediately.)
The effect of these drugs takes time to build up. You should take them regularly for at least four weeks before deciding whether they are helping you or not.
One point in favour of cromoglycate-type drugs is that they are extremely safe, with few or no side effects in most people. Sadly, they do not work for everyone. A fairly high percentage of children respond well to them, but the response rate is much lower for adults. Nevertheless, adult allergy sufferers, especially those who need steroids to control their symptoms, should always be given the opportunity to try out these drugs. When cromoglycate-type drugs do work, they are very effective and almost always trouble-free, so they are a good alternative to steroids.
Both sodium cromoglycate and nedocromil sodium are available in inhaler form for asthma (see p. 157). Sodium cromoglycate is also available as nose drops for hayfever and other nasal allergies.
All three drugs are available as eye drops. Recent evidence suggests that sodium cromoglycate drops are less effective than the other two, particularly for the treatment of severe allergic conjunctivitis (inflammation of the eye).
Sodium cromoglycate is available in capsule form for food allergy. Note that these capsules are of very limited value in food allergy, and are certainly not a substitute for food avoidance. They do reduce sensitivity a little and can sometimes be helpful for those with multiple food allergies (see p. 67).
Side effects
There are no serious side effects at all for nedocromil sodium. cromoglycate can, very rarely, cause joint pain and swelling. An allergic reaction to the drug itself is even more uncommon. Stop taking the drug and see your doctor promptly if either of these occurs.
The only other side effects that have occasionally been reported are headache, nausea and vomiting. None of these indicates any damaging effect by the drugs – they are all minor side effects.
Eye drops containing these drugs may cause stinging and burning when inserted, but this is a minor side effect and usually wears off. Flushing and dizziness have sometimes been reported with lodoxamide eye drops.
Nose drops may also cause local irritation. This could be due to the drug itself, in which case it is a minor side effect. Alternatively, the irritation may be due to the preservative used or some other non-drug ingredient (see box on p. 33).
Occasionally cromoglycate nose drops cause bronchospasm – contraction of the airway muscles – but this tends to wear off quite quickly. Bronchospasm can also occur when cromoglycate-type drugs are inhaled (see p. 157).
Anti - leu kotriene drugs
These drugs, which have a set of very specific effects (see p. 159), were originally designed to treat asthma. Their potential for treating other allergic diseases is currently being explored:
•    Several studies show that they work well for perennial allergic rhinitis brought on by allergens such as house-dust mite. They also have some effect on hayfever, but standard treatment (such as antihistamines plus a steroid spray for the nose) is more effective.
•    They are especially useful for both rhinitis and asthma in patients suffering from triad (see box on p. 28). Research shows that they also reduce asthmatic reactions to very small test doses of aspirin, but they don’t give protection against anaphylaxis brought on by normal doses.
•    They have also been used successfully in cases of chronic urticaria and for some patients with delayed pressure urticaria. It seems plausible that they would also be helpful for chronic urticarla linked to aspirin sensitivity.
•    Preliminary trials suggest that these drugs might be useful in atopic eczema. Some studies show a very good response that allows a reduction in steroid creams.
•    Montelukast works very well for eosinophilic gastroenteritis and eosinophilic oesophagitis (see p. 72), according to some new studies.
For side effects of these drugs see pp. 159-60.
Anti-IgE drugs
Since the antibody IgE (see box on p. 12) is such a crucial player in allergic reactions, developing drugs that disable this antibody should help allergy sufferers. The first such drug is omalizumab (brand name Xolair) which was licensed for use in the United States in 2003. It is expected to become available in Britain some time in the next few years.
Omalizumab binds to IgE antibodies and stops them from interacting with mast cells, so blocking any allergic reaction. The drug is given as a ‘depot injection’, just under the skin, every 2-4 weeks. It is gradually released from the injection site and moves around the body in the blood, mopping up IgE molecules.
At present, omalizumab is used for severe hayfever and for people with asthma who are not responding well to the usual treatments. It is only worth using if there is clear evidence that allergies play a part in the asthma. Patients who use omalizumab are often able to reduce their dose of inhaled steroids – and they suffer fewer serious asthma attacks and have better lung function. Some patients can even stop using steroids completely.
Other anti-IgE drugs are in the pipeline. Pilot studies show that one works very well for peanut allergy: after just four injections, sensitivity to the allergen falls sharply, reducing the risk of anaphylaxis from traces of peanut eaten accidentally.
More powerful anti-allergy drugs
Occasionally people with severe allergies, who are on constant high doses of steroid tablets, or who fail to respond to steroids, need treatment with powerful anti-inflammatory drugs, such as methotrexate or cyclosporin. These suppress the immune system, and extremely careful monitoring for side effects is needed.
Adrenaline (epinephrine)
Anyone who has suffered anaphylactic shock (see p. 58) should be carrying a special syringe, called an auto-injector, loaded with adrenaline. The injector is very simple to operate and is designed for emergencies. Most allergy sufferers, even children, can give themselves the injection – or a parent or other adult can give it.
Some asthmatics, and those with food allergy who suffer swelling of the throat, may be given adrenaline in inhaler form as well (see pp. 155-6). This can be useful as an additional treatment but it’s definitely not a substitute for an injector.
See pp. 98-9 for instructions on using adrenaline in a crisis.
Wherever you go, take your injector with you. Always keep it close at hand: you need to be able to use it within minutes of the allergic reaction starting. You may be unable to speak (and therefore unable to ask someone else to fetch it) quite soon after the attack begins. The injector must never be refrigerated. It can also be damaged by sunlight and excess heat.
If you live in the countryside or in an area with a poor ambulance sevice, or if you are going camping or hiking somewhere remote, ask your doctor for a second injector, or one that can deliver multiple injections. Also ask about the maximum number of injections that can be given, and never exceed this total. Some doctors believe everyone should have two injectors, just in case the first dose doesn’t do the trick and help is slow in coming.
It is vital that you are shown exactly how to use the auto-injector. Canadian researchers discovered that only one in four
Some common brand names
Common brand names of adrenaline preparations include: auto-injectors – Anapen, EpiPen
inhalers – AsthmaHaler Mist, Bronkaid, Epiphrine
health professionals got the technique correct when demonstrating how to use an auto-injector In this study, pharmacists were much the best as regards accurate instructions. Dummy injectors are useful for training purposes and most pharmacies have them.
When the adrenaline auto-injectors expire, they can be very useful for practising with, or for showing a new baby-sitter or teacher – practise on an orange or grapefruit.
If you are taking beta-blockers (e.g. for a heart condition or anxiety), adrenaline may not have much effect.
Heavy daily use of beta-2 relievers for asthma (see p. 152) will also make adrenaline less effective when you need it.
Side effects
The important side effects of adrenaline involve the heart. Anyone with a heart condition should be given special advice in advance by their doctor about using adrenaline. The same goes for people with diabetes, hyperthyroidism or high blood pressure, and anyone taking tricyclic anti-depressants. There are quite a few minor side effects from adrenaline, such as anxiety, trembling, nausea. sweating, dizziness and cold extremities. These soon wear off.
Drugs that can make you worse
Aspirin and its relatives have a very bad effect on some people with rhinitis and/or asthma (see box on p. 151). Unfortunately, recent research shows that paracetamol is not safe either. It makes asthma more likely to develop in those who do not yet have the disease, and increases the severity of asthma symptoms for those who do. Unlike aspirin, paracetamol affects everyone, because it lowers the levels of a natural antioxidant, called glutathione, which the body makes to protect the lungs from oxidants. The greatest effects are seen in people who take paracetamol regularly (once a week or more), but even an occasional dose makes some difference.
All the other drugs that can make you worse are prescription drugs, and your doctor should be alert to the dangers. But doctors are overworked and sometimes forget, so it is sensible to know about the risks for yourself. If you have any doubt about the drugs you are taking, ask a pharmacist.
Beta-blockers are a major hazard for people with allergies. They can make the airways contract, and can bring on a serious asthma attack. They also make anaphylaxis more likely in someone who already has allergic reactions (see p. 59) and they increase the risk of a severe reaction to
immunotherapy (see p. 166) or skin-prick tests (see p. 91). Beta-blockers are prescribed for high blood pressure, angina and other heart problems, migraine and thyroid disease. There are alternative drugs in all cases. Sometimes asthma develops in people who have been taking beta-blockers for years. The beta-blockers are not responsible for this, but once asthma has begun, they will make symptoms worse. Eye drops for the treatment of glaucoma may also contain beta-blockers and can have a bad effect on asthmatics.
ACE inhibitors, used for heart conditions, may cause a cough and airway narrowing. They may also increase the risk of a severe reaction to immunotherapy.
Female hormones affect asthmatics, so taking the contraceptive pill or hormone replacement therapy (HRT) may make asthma worse. Progesterone-only contraceptive pills tend to cause fewer problems.
The drug isoniazid (INH), prescribed for tuberculosis, makes the body far more susceptible to histamine in foods (see p. 200).
An allergic reaction to a specific drug (e.g. penicillin) can also occur in some people, resulting in urticaria, or even anaphylactic shock.
Aspirin sensitivity
Aspirin sensitivity is not an allergic reaction, because neither IgE nor mast cells are involved. What causes this problem is a metabolic abnormality — a malfunction in one aspect of the body’s chemistry. The details of this are very complicated: you may want to skip the next three paragraphs and
simply read about how to cope with the problem.
The exact nature of aspirin sensitivity is still far from clear, but it seems to involve a relatively poor production of prostaglandins, combined with a plentiful production of leukotrienes. Both these substances are messenger chemicals which, broadly speaking, promote inflammation. But the details of their pro-inflammatory activities differ. It seems that, ideally, the body should have a harmonious balance between the two, and an imbalance produces problems.
Both prostaglandins and leukotrienes are manufactured from certain fats that are found in the diet. These fats, the raw materials, are worked on initially by two different enzymes — one that leads to the production of prostaglandins and another that leads to the production of leukotrienes.
If one of these enzymes is defective, it may mean that the other is oversupplied with raw materials, resulting in a serious imbalance between prostaglandins and leukotrienes. In those with aspirin sensitivity, or at risk of developing aspirin sensitivity, the enzyme that produces prostaglandins seems to be defective.
Even in the absence of aspirin, this imbalance in the production of prostaglandins and leukotrienes causes problems. It leads to symptoms such as chronic urticaria (see p. 51) or rhinitis, nasal polyps and asthma (a cluster of symptoms that is commonly called triad — see box on p. 28).
Taking aspirin can make the imbalance between prostaglandins and leukotrienes even worse in a person with this underlying abnormality. Aspirin exerts its painkilling effects by disabling the main prostaglandin-making enzyme — the enzyme that is already defective.
When someone with aspirin sensitivity takes aspirin, they may suffer worsening asthma, a severe asthma attack or — the worst-case scenario —collapse. This is a potentially fatal reaction, similar to anaphylaxis, requiring emergency medical treatment (see p. 101).
The greatest puzzle about aspirin sensitivity is why it often takes so long to develop in someone who already has the symptoms of triad —indicating the basic metabolic abnormality. It may be as much as 20 years from when someone has their first triad symptoms to when they begin reacting badly to aspirin.
If you have triad symptoms already, but no aspirin sensitivity yet, what should you do? Unfortunately, there are no safe tests for aspirin sensitivity at present — taking a small dose of aspirin and seeing what happens is very hazardous. It is probably best to assume that you are going to become sensitive to aspirin at some stage, and avoid all aspirin and aspirin-like drugs. Caution is the best plan here because aspirin sensitivity can come on very suddenly, and be life-threatening the very first time it occurs. Note
that some triad sufferers have polyps and rhinitis but no asthma until they actually develop aspirin sensitivity — a dose of aspirin suddenly brings on their first asthma attack plus other symptoms of aspirin sensitivity.
Avoiding aspirin itself is not difficult, but aspirin-like drugs pose more of a problem. Every year there are a number of deaths from these drugs. Some cases occur because a busy doctor momentarily forgets that a patient should not take these drugs. The drugs that need to be avoided are all known as non-steroidal anti-inflammatory drugs (NSAIDs), COX-1 inhibitors or COX-2 inhibitors. However you will not see any of these names on the packet. These drugs are very widely used for pain relief (e.g. in headache and backache remedies such as Nurofen), for the treatment of arthritis, and for several other inflammatory diseases.
There are dozens of non-steroidal anti-inflammatory drugs available, and many are sold under several different brand names. The list grows every year, as new drugs or new brands are launched. The only way to avoid these drugs is to be very cautious:
•    When buying any cold- or flu-remedies, painkillers, medicines for sprains or sports injuries (including those you apply directly to the skin), headache tablets or migraine tablets, always buy them at a chemist’s shop rather than a supermarket, and check with the pharmacist that they do not contain aspirin or aspirin-like drugs.
•    Be cautious also about remedies for an upset stomach. A few (e.g. Alka-Seltzer) contain aspirin.
•    Don’t take any drugs unless you are 100% sure of what they contain. Remember that the ingredients of a familiar brand name can sometimes change — read the label every time.
•    When a doctor prescribes any new drug, always mention that you are sensitive to aspirin, or that you have triad symptoms. Alternatively, check with the pharmacist when the prescription is filled.
•    Aspirin-free painkillers almost always contain paracetamol, a drug which can cause a severe reaction (similar to the collapse induced by aspirin itself) in about 5% of those with aspirin sensitivity. If you are taking paracetamol for the first time, start with half a tablet. Be sure that, for the next 2-3 hours, you have a way of getting to hospital quickly should you start to feel ill. (Note that paracetamol has another entirely separate effect, increasing the severity of asthma, and it is best not to take it too often — see box on p. 150.)
Avoiding all aspirin-like drugs will prevent you having anaphylaxis or severe attacks of asthma. Unfortunately, triad symptoms will not go away however careful you are about avoiding aspirin.
It is well worth trying the new anti-leukotriene drugs (see p. 149), especially if you have aspirin-induced asthma. They seem to help with triad symptoms by curtailing the activities of leukotrienes and so redressing the balance between leukotrienes and prostaglandins.

Antihistamines and Allergy

Tuesday, May 19th, 2009

Antihistamines and Allergy

Antihistamines were first introduced in 1947, and are very widely used, so their safety — at least in the case of the older antihistamines — is beyond doubt. Most of the antihistamines have no major ill effects, and no one should feel concerned about taking them. At worst they produce some rather annoying minor side effects, such as drowsiness, which often wear off in time.

These drugs are particularly valuable for hayfever and other allergies in the nose (perennial allergic rhinitis). They are also used for chronic urticaria, sometimes in combination with anotherhistamine-blocking drug — see p. 53.

Antihistamines are not much used for asthma. They have relatively little effect, probably because so many other messenger chemicals are involved in an asthma attack. However, doctors in Japan do use antihistamines for asthma, and it is possible that people of Asiatic origin react differently to them.

Only one antihistamine, ketotifen, is widely used for asthma in the West, and this has other effects besides blocking histamine (see p. 159). A new role may soon develop for antihistamines in thetreatment of asthma, combined with anti-leukotriene drugs (see p. 159).

If you suffer from anaphylaxis you might be given antihistamines in a liquid or chewable form, for use in an emergency. These are not enough in themselves to treat this dangerous condition - you must have an adrenaline injector (see p. 150).

In the past, some doctors prescribed antihistamines for atopic eczema, mainly for their sedative effect(see p. 139) which was thought to help children to sleep better and scratch less at night. This treatment has largely gone out of favour, because its value is in doubt. But a recent study has revealed that the non-sedating antihistamine cetirizine may be useful for very young children with atopic eczema, not only in treating their skin, but also in reducing the chance of them developing asthma (see p. 249).

Most people take their antihistamines in tablet or capsule form. Syrups and sugar-free elixirs areavailable for children.

Antihistamines can also be applied directly, in the form of nasal sprays or eye drops. These are mainlyused to treat hayfever and the conjunctivitis (inflammation of the eye) which often accompanies it.Levocabastine (brand name Livostin) is particularly effective for the eyes.

Antihistamine creams are also sold, without prescription, for the treatment of insect bites - i.e. thenormal non-allergic reaction to such bites. These creams are not recommended for atopic eczema or otherallergic conditions affecting the skin. Not only are they unlikely to help, but they may make mattersworse because, with regular use, skin sensitisation to the antihistamine occurs very readily (see pp.54-5).
Some common brand names

Common brand names include: non-sedating antihistamines - Clarityn, Semprex, Zirtek; Mistamine, Mizollen, Telfast, Terfenadine. Thefirst three are available without prescription.

older (sedating) antihistamines — Atarax, Dimotane, Optimine, Periactin, Piriton, Tavegil, Vallergan eye drops — Emadine, Livostin, Optilast nasal sprays — Livostin, Rhinolast

How antihistamines work
Of the messenger chemicals released when an allergic reaction occurs, the most important is histamine.

This does its work by attaching to specialised receptors in certain parts of the body, and so

triggering various reactions (see box on p. 12). The action of antihistamines is very simple: they bind

to the same receptors as histamine, but they do not trigger any reaction. Histamine cannot bind to the

receptor because the antihistamine is already there.
Unfortunately, the reverse is also true: if the histamine is already there, the antihistamine cannot

elbow it off the receptor, which is why it is important to take the antihistamine well before the

allergen is encountered. Taking antihistamines at the first sign of a snuffle or itch can also work,

but the effects will not be nearly as good as taking them in anticipation of an exposure.
The best approach to treating hayfever, for example, is to start taking the antihistamines at least a

week before the pollen season begins, and preferably two to three weeks before. You should then take

them continuously until it is over. This will make a huge difference to the degree of symptom control

you achieve.
Side effects
The older types of antihistamine, such as chlorphenamine (brand name, Rriton) are relatively

non-specific in their effects – they bind to several different kinds of receptors, not just those for

histamine. As a result they can have some unwanted effects, such as causing drowsiness and poor

coordination. While these sedative effects are no cause for concern in themselves, they can, of course,

be hazardous if you work with dangerous machinery or drive. Avoid both until you are sure how you react

to the antihistamine. Note that the effects of alcohol may be increased.
Very occasionally antihistamines have the opposite effect, causing stimulation rather than sedation;

this is most likely to occur in children and old people. Lowering the dose may solve the problem.
The other possible side effects of the older antihistamines –all of which are minor ones – are

headache, dry mouth, blurred vision, difficulty in passing urine, nervousness, shaky hands, upset

stomach or diarrhoea. A few men suffer impotence while taking antihistamines, but this disappears when

the drug is stopped.
The minor side effects of antihistamines, including drowsiness, often wear off after a while, although

the benefits of the drug remain. So it is worthwhile persisting with an antihistamine, even if it

causes some problems at first. Many people experience side effects from certain antihistamines but not

from others, so try several different types to find one that suits you.
The problem of drowsiness has been reduced, in recent years, thanks to the development of new drugs

that are far more
specific for histamine receptors, the non-sedating antihistamines. A few people do get drowsy even with

these drugs. Again, the effects vary from one drug to another, so if the first one disagrees with you,

try a different one.
It is worth noting – since some people may still have the odd packet in their medicine cabinet – that

two of the non-sedating antihistamines that were available without prescription a few years ago proved

to be unsafe for a small minority of people. One was astemizole (brand names: Hismanal, Pollon-eze),

which has now been withdrawn from use altogether in Britain. The other was terfenadine (brand names:

Triludan, Seldane, Terfenadine) which is still available, but only on prescription.
There are several special precautions relating to terfenadine:
• Never exceed the correct dose.
• If you have ever had any kind of heart problem, talk to your doctor before taking terfenadine.
• Stop taking the drug if you have palpitations, or if you feel faint; see your doctor promptly.
• Do not take terfenadine if you are taking the antibiotic erythromycin, or anti-fungal drugs

such as ketoconazole (Nizoral) or fluconazole (Diflucan), used to treat vaginal thrush.
• Do not take terfenadine if you have liver disease.
• Do not drink grapefruit juice while taking terfenadine: something found naturally in grapefruit

interacts unpleasantly with this antihistamine.
In addition to these special precautions concerning terfenadine, any antihistamine should be treated

with caution by those suffering from epilepsy, Parkinson’s disease, glaucoma, prostate enlargement,

kidney problems, urinary retention, a gastric ulcer, a thyroid disorder, porphyria or liver disease.

Check with your doctor before taking antihistamines if you have any of these conditions.
It may be inadvisable to use antihistamines if you are taking sleeping tablets, anti-depressants or

anti-anxiety drugs – again, see your doctor.
Stop taking antihistamines if you suffer any unusual kind of rash, or if your skin becomes more

sensitive to sunlight.
If you are breast-feeding, note that, because they go through into the milk, the older antihistamines

may make the baby sleepy. However, they do no harm.
Rescue treatment
Most antihistamines perform very badly if you take them once the allergic reaction has set in, but

acrivastine (Semprex) can be good in these circumstances and is non-sedating. No prescription is

required for this drug.
possibly identify all major side effects. We vary in our response to drugs, because we are all so

different at the chemical and cellular level. A drug might have a serious side effect that only affects

one person in 10,000, and no safety trial can hope to identify such a rare response. Only when a drug

is released, and becomes widely used, do such side effects come to light. Other unanticipated side

effects can sometimes arise when people taking the new drug are much older than those in the safety

trials, or belong to a different ethnic group with different susceptibilities. Combining the drug with

certain other drugs can also be a potential source of trouble, although pharmaceutical experts can

often predict such problems from a detailed knowledge of the chemistry of drugs and how they are broken

down in the body. Side effects that take several years to develop - more than the timespan of most

safety trials - will also fail to show up until the drug has been released.
All this may sound very alarming, but in fact severe reactions to new drugs are not that common. And

there are various safety nets in place - doctors keep a close eye on patients taking new drugs, and a

special reporting system ensures that, if unexpected side effects do show up, the information is

quickly shared with others in the medical community.
In order to relate the information here to a particular medicine that you take, you need to know what

drug category it belongs to. Does your inhaler contain a beta-2 reliever, a steroid, a cromoglycatetype

drug or an anti-cholinergic, for example? If you are not sure, ask your pharmacist.
Those are the category names for drugs: they denote families of drugs which are similar chemically
and work in roughly the same way. Within each category, or family, there are a number of individual

drugs. The individual drugs should, ideally, have a standard internationally agreed name - this is

known as the generic name. Unfortunately, a few of the drugs used for allergies and asthma have more

than one generic name - salbutamol is known as albuterol in some parts of the world, and adrenaline is called epinephrine.

Finally there are the brand names, which are the ones most patients are familiar with. These are always

shown with a capital letter, unlike the generic names. Long-established drugs are usually made by

several different pharmaceutical companies, and therefore marketed under several different brand names.

A newer drug, which is still covered by the patent of the pharmaceutical company that developed it,

will be sold under only one brand name.

The issue of brand names is important, because a different brand name might make you think you are taking a different drug, when in fact it is exactly the same drug being marketed in a different guise.If you have suffered side effects from a particular drug in the past, and wish to avoid it in future, take note of its generic name, rather than its brand name. Sometimes the generic name is used as the brand name, in what are called generic drugs. These arerelatively inexpensive copies of popular drug brands -they are just the same chemically, but they costless because there is no advertising of the brand to doctors, and profit margins have been cut to aminimum. In order to reduce National Health Service costs, doctors are now asked to prescribe generic drugs whenever possible.