Posts Tagged ‘terfenadine’

metronidazole An orally effective drug used in trichomoniasis, amoebiasis and in infections due to anaerobic bacteria. Dose: in bacterial and trichomonal vaginitis, 600 ing daily for 7 days, or as a single dose of 2g. In acute intestinal arnoebiasis, 2.4 g daily for 3 days. In surgical prophylaxis, and in the prophylaxis and treatment of infections caused by colonic anaerobic pathogens such as Racteriodes ftagilis, as well as infections by some Gram-negative organisms. metronidazole is given in doses of 1.2 g daily orally, or as I g suppositories. In severe infections, doses of 1.5 g are given daily by i.v. infusion, replaced by oral therapy as soon as possible. In Giardia laniblia infections, 2g daily for 3 days; 600 mg daily for 3 days in ulcerative gingivitis. Metronidazole is also valuable in pseudomembranous colitis (see clindamycin). Side-effects are mainly gastrointestinal disturbances and can be reduced by giving the close with food, but epileptiforni seizures may occur with high doses, and the drug may cause a disulfiraintype reaction if alcohol is taken. (Flagyl). Metronidazole is also used as a 0.750% gel (Metrogel; Rosex) in rosacea and as Anabact ail(] Metrotop to deodorize malodorous tumours.
metyrapone Ail inhibitor of glucocorticoid synthesis.
Dose: 750 mg 4-hourly for 6 doses as a Icst of anterior pituitary function, as following such doses the plasma concentration ofcorticosteroids falls. The fall stimulates the production of steroid pre cursors by the adrenal glands, and a rise in the urinary excretion of such precursors is indicative of an active anterior pituitary gland. Metyrapone is also used in resistant oedema due to ail increased production of aldosterone, and in the symptomatic con-I rol 01′ Cushing ’s syndrome. Nausea and vomiting are side-effects. (Metopirone).
mexiletine Ail anti-arrhythmic drug that is useful in the control of ventricular arrhythmias, particularly those following myocardial infarction, or when lignocaine is ineffective.
Dose: as a loading dose, 100-250 mg i.v. under I-I’C6 control, followed by i.v. infusion of a 0.1% solution until a further 250 mg have been given. Oral therapy: a
loading dose of 400 mg, followed by 600mgI g daily. Side-effects are nausea, drowsiness, confusion and blurred vision. Contraindicated in bradycardia, hypotension, and hepatic or renal failure. (Mexitil).
mianserin An antidepressant of the amitriptyline type, with reduced anticholinergic and cardiovascular side-effects, and well tolerated by the elderly. It is of value in all types of depression, including those associated with anxiety. Dose: 30-90 mg daily, which may be taken as a single close at night, although higher doses have been given. Care is necessary in recent myocardial infarction and heart block. Severe hepatic disease is a contraindication. Side-effects include aplastic anaemia,and blood counts during treatment are essential. The drug should be withdrawn if any signs of infection occur. See page 128 and Table 11.
miconazole An antiftingal agent of value in systemic and alimentary fungal infections. Dose: I g daily orally, or up to 1.8 g daily by i.v. infusion, and the duration of treatment largely depends on the response.
Pessaries of 100 mg and a cream (2%) are used for vaginal candidiasis. A gel is available for oral fungal infections. Side-effects after systemic use include nausea, pruritus and rash. Miconazole may potentiate the action of anticoagulant, anticonvulsant
and hypoglycaemic drugs, requiring an adjustment of close. Combined use with asternizole, terfenadine and cisapride should be avoided. (Daktarin).
midazolam A sedative of the benzodiazepine group, used mainly for sedation before and during gastroscopy, endoscopy and other investigations. The action is rapid, and an anterograde amnesia often follows.
Dose: by slow i.v. injection 70pglkg tip it) a total d2.5-7 mg. premedication, 2.5-5 mg i.m. For the induction of anaesthesia in poor-risk patients, 104-300pg1kg by slow i.v. injection. Side-effects after i.v. injection include respiratory depression and, occasionally, severe hypotension. (Hypnovel).
mifepristone An antiprogestational agent used as ail alternative to surgery for the termination of pregnancy, up to 63 days’ gestation.
Dose: a single oral dose of 600 mg. For hospital use only. (Nfifegyne).

milrinone An inhibitor of phosphodiesterase, an enzyme concerned in cardiac function. It has a digoxin-like effect on the myocardium, and may be effective in congestive heart failure not responding to other drugs.
Dose: by i.v. infusion as an initial dose of 50 pg1kg, with maintenance doses of 0.5 pg/min up to a total of 1.13 nig/kg over 24 hours. Side-effects are anginal pain, hypotension and headache. (Primacor). See enoximone, page 141 and Table 18.
minocycline A tetracycline with the general properties of that group of antibiotics, with the advantage of being useful in meningococcal prophylaxis. The absorption of minocycline is little influenced by food. It is also suitable for use when the renal function is impaired, as accumulation of the drug is unlikely.
Dose: 200 mg daily. In acne treatment half-dose should be given for 0 weeks. The side-effects are those of the tetracyclines generally, although monocychne may also cause dizziness, vertigo and rash. (Minocin).
minoxidil A vasodilator used in severe hypotension resistant to other drugs. Dose: 5-50 mg daily. Side-effects are Wright gain, breast tenderness and tachycardia. Almost all patients experience hyper1richosis, and should be warned accordingly. (Loniten). A 2% solution is used as a lotion in the local treatment of male-pattern baldness. (Regaine).
mirtazapine An alpha,-receptor antagonist. It is used in depression as it increases central noradrenergic and serotenergic neurotransmission. rot ransmission.
Dose: 15-45 nag at night for 4-6 months. Side-effects are weight gain and drowsiness. (Zispin).
misoprostol A synthetic prostaglandin with an inhibitory action on gastric secretion. It is used in the control of peptic ulcer, and in the prophylaxis of ulcers induced by non-steroidal anti-inflaniniatory drugs (NSAIDs).
Dose: 800pg daily with food, with a last dose at night, and continued for some weeks. Dose in prophylaxis, 400-800µg daily. Side-effects are usually transient, and
.    include diarrhoea, nausea and abdominal pain. (Cytotec). See page 162. Contraindicated in pregnancy.
mitobronitol A cytotoxic agent used mainly in chronic myeloid leukaemia.
Dose: 250 nag daily until the white cell count falls, then 125 mg daily according to need. May cause gastrointestinal disturbance, alopecia and bone marrow depression. Haematological control is necessary. (Myclobromal). See page 122 and Table 8.
mitomycin A cytotoxic antibiotic used in bi cast, gastrointestinal and other cancers. Dose: 4-10 mg by i.v. infusion at intervals of I-6 weeks. Great care must tic taken to avoid extravasation. Also used in bladder cancer by the weekly instillation of a solution of 10-40 nag in 20-40 nil of water. Side-effects include bone marrow and renal damage, and lung fibrosis.
mitozanitrone A cytotoxic drug related to doxorubicin, and indicated in advanced breast cancer.
Dose: 14 nighn= once i.v., repeated after 21 days, provided the white cell and platelets counts have returned to normal. It is highly irritant, and contact of the drug wid the skin must be avoided. Side-effects are nausea, vomiting, alopecia, myelosuppression and cardiac weakness. (Novantrone). See page 122 and Table 8.
mivacurium A non-depolarizing muscle relaxant with the short action and uses of atracurium.
Dose: initial dose 70-250pg/kg i.v., followed by doses of 100µg/kg/min at intervals of 15 minutes as required. Smaller doses are given by i.v. infusion. (Mivacron).
moclobemideVA short-acting, reversible inhibitor of monoamine oxidase (MAO) for the treatment of severe depression. The older MAO-inhibitors act on both the A- and B-forms of the enzyme, and have a long and irreversible action. Moclobemide has a rapid and selective action on MAO-B, but the duration is short and fades after about 24 hours, as the drug is soots    The risks of reactions with other drugs (comnlon with old MAO-inhibitors) are correspondingly reduced.
Dose: 300 mg daily initially (after withdrawal of other therapy), slowly increased up to 600 ing daily. Side-effects are dizziness and sleep disturbances. (N-lanerix). See page 128 and Table 11.

moexepril An ACE-inhibitor.
Dose: (when given alone) 7.5 mg daily initially, increasing if required up to 30 mg daily. When given as a second-line therapy with a diuretic (which should be avoided), initial dose is 3.75 mg under supervision until the blood pressure has stabilized. Side-effects are hypotension and cough. I lyperkalaernia may occur if potassium supplements or potassium sparing diuretics are also given. (Perdix). See page 148 and Table 21.
molgramostimVA recombinant form of human granulocyte macrophage colony stimulating factor (GM–CSF). It is used in the neutropenia following cytotoxic and bone marrow transplant therapy.
Dose: 60 000-100000 units by s.c. injc, tion or i.v. infusion, under haematological control. (Leucomax). See filgrastini and lenograstini.
mometasoneVA potent corticosteroid used as 0.1% creamilotion once a day in severe eczema, psoriasis and other skin conditions not responding to other therapy. (Elocon). Also used as a nasal spray in allergic rhinitis. (Nasonex).
monoamine oxidase inhibitors Monoaniine oxidase is an enzyme concerned with the breakdown of dopamine, serotonin, noradrenaline and adrenaline. Those substances are stored in many organs of the body, including the brain, where they function as transmitters of nerve impulses. The period for which they act is very short, as they are rapidly metabolized by monoamine oxidase. An inhibition of the enzyme could permit an increase in the brain levels of such amines, and on that basis sonic monoamine oxidase inhibitors (MAOIs) have been used in the
treatment of depression. Therapy is complicated by the fact that these drugs can increase the response to pressor drugs, anaesthetics and many other agents, including the mild sympathominictics present in some cough
mixtures and decongestive nasal sprays. Even certain foods, particularly cheese, may cause a dangerous rise in blood pressure during MAO] therapy and patients should always carry the MAN warning card. Great care is necessary during combined therapy, and ideally 10-14 days should elapse after ceasing
MAGI treatment before using other potent drugs. Examples of MAOIs are isocarboxazid, phenelzine and tranylcypromine. Their use has declined as more effective antidepressants of the amitriptyline type, with fewer side-effects, have become available. See moclobemide, page 128 and Table 11.
moraeAzine A potent cardiac membrane-stabilizing agent used like lignocaine to control ventricular arrhythmias.
Dose: 600-900 mg daily initially, adjusted later according to need and response. Side-effects include dizziness, palpitations and chest pain. (Ethniozinc),
tmorphine The principal alkaloid of    71 Opium. It is widely used as a narcotic analgesic for the relief of severe pain and the associated anxiety and stress, and in shock.
Dose: in acute pain, 10 mg by injection as required; in chronic pain it may be given orally or by injection according to need in doses varying from 5-10 mg. Sonic long-acting oral forms of
morphine are available (MST Continus; Oramorph SR) designed to reduce the frequency of dosing in conditions of severe pain. Side-effects include nausea and vomiting, which can often be controlled by small doses of chlorpromazine, or a similar antiemetic.
Morphine may cause respiratory depression, and severe respiratory depression is a contraindication. The possibility of tolerance to and dependence on morphine should be kept in mind if treatment is prolonged, but in terminal Conditions is of little importance.
moxisylyte (thymoxamine) An alpha,- adrenergic blocking agent, given by intracavernous injection for the induction of erection.
Dose: 10 mg not more than 3 times a week. Side-effects are drowsiness. dizziness and flushing. (Erecnos).
moxonidine A centrally acting antihypertcjisive agent of the clonidine type. It has a greater affinity for certain receptors in the brain stem that reduce the peripheral resistance and so indirectly lowers the blood pressure.

chymotrypsin A proteolytic enzyme of the pancreas used in ophthalmology to facilitate intracapsular lens extraction. (Zonulysin).
cidofovir An antiviral agent used in cytomegalovirus retinitis resistant to ganciclivir.
Dose: 5 nig/kg by i.v. infusion every 2 weeks. (Vistide). See page 144 and ‘['able 19.
cilastatin See imipenem.
chlorthalidone A diuretic similar in action and uses to bendrofluazide, but with a longer duration of activity that permits a single morning dose. It is also useful in diabetes insipidus.
Dose: as diuretic 50-100 mg daily or on .illci nale days; in hypertension 25-50 mg; up to 350 mg daily in diabetes insipidus. (I lygrolon ). See page 148 and Table 21.
cholecalciferol See vitamin D.
cholestyramine An exchange resin that binds with bile acids in the intestines and prevents their absorption. Such acids are essential for cholesterol synthesis, and resin-binding leads indirectly to a lowering of plasma cholesterol levels.
Dose: in hyperlipidaemia: 12-24 g daily, wilh water; similar doses in the diarrhoea of Crohn's disease. It is also used in doses of 4-8 g daily to relieve the pruritus
associated with biliary obstruction. Side-effects are rash and gastrointestinal disturbances. Cholestyramine and related agents may interfere with the absorption of anticoagulants and other drugs. iQuestrari). See page 146 and Table 20.
choline theophyllinate A bronchodilator ,ilh the actions, uses and side-effects of anlinophyllille.
Dose: 400-1600 mg daily, after food. (C'I ioledyl). See page 118 and Table 6.
chorionic gonadotrophin A gonad-stimulating hormone prepared from the Urine of pregnancy. It has bten used in anovulalory sterility, metropathia haernorrhagica, habitual abortion and undescended testis.
cilazapril A long-acting ACE inhibitor with the actions, uses and side-effects of that group of drugs.
Dose: in essential hypertension 1 mg daily initially, increased up to 5 mg daily according to need. In renovascular hypertension 0.25-0.5 mg daily. (Vascace). See page 148 and'I'able 21.
cimitidine A selective histamine H, receptor antagonist. Unlike ordinary antihistamines, it inhibits gastric secretion, and is used in the treatment of peptic ulcer and other conditions of gastric hyperacidity. Dose: 8(m) nig daily for at least 4 weeks, doubled in severe conditions. Dose by i.m. or slow i.v. injection 200 mg 4-4-hourly. The dose should be reduce(] in renal impairment. The drug may increase the effects of oral anticoagulants and phenytoi ii. Side-effects include diarrhoea, rash and dizziness. It has some anti-androgen activity, and gynaecomastia is all occasional side-effect with high closes. (Dysparneu Tagarnet; Zila). See page 162 and Table 27.
cinchor-aine A local anaesthetic used as
ointment 1% in haemorrhoids and
pruritus. (Nupercainal).
cinnarizine An antihistamine, chiefly of value in Wniere’s disease, although it is also used in travel sickness and in peripheral vascular disorders.
Dose: 45-90 ing daily. Drowsiness and gastrointestinal disturbances are side-effects. (Stugeron).
cinoxacin A quinolone derivative with actions, uses and side-effects similar to i hose of nalidixic acid.

Dose: in urinary tract infections,  daily; prophylaxis 500mg daily. Contraindicated in severe renal impairment. (Cinobac).
ciprofbrate A blood-lipid lowering agent used in diet-resistant hyperlipidaemia as a single daily dose of 100-200 mg. (Modalim). See page 146 and Table 20.
ciprofloxacin A quinolone with a wide range of activity against both Gram-positive and Gram-negative bacteria, including Pseudomonas and Fronts. It is effective in many systemic infections, as well as in bone, joint and urinary infections, and in gonorrhoea, but is indicated mainly in infections resistant to other antibacterial agents. Dose: 500 mg -1.5 g daily for 5-7 days; in gonorrhoea, a single dose of 250 mg is given. In severe infections 200-400 mg daily by i.v, infusion for 5-7 days. Side-effects include nausea, dizziness, headache, rash and pruritus. plasma levels of theophylline may be increased and should be closely controlled. Care is necessary in convulsive disorders. (Ciproxin).
cisapride A gastrointestinal stimulant given to relieve gastro-oesophageal reflex and delayed gastric emptying.
Dose: .10-40 mg daily before meals, and at night, for some weeks. Side-effects are abdominal pain and diarrhoea. Drugs that delay the excretion of cisapride and may cause arrhythmias are erythromycin and clarithromycin-antigungal agents of the ketoconazole type should also be avoided. Unlike metoclopramide, it has no central antiemetic properties. (Alimix; Prepulsin).
cisatracurium A non-depolarizing neuromuscular blocking agent with an intermediate duration of activity. It is used as a muscle- relaxing adjunct in general anaesthesia, and to facilitate tracheal ininhation. (Nimbly).
cisplatin A cytotoxic agent containing platinum bound in an organic complex. The action is linked with drug-induced changes in DNA structure that inhibit cell development. It is used in ovarian, testicular and other solid tumours, and in resistant malignant conditions, sometimes in association with other antineoplastic agents.
Dose: by i.v.  for 5 days a month, or 15-120 mgIm’ monthly. Blood tests are essential
throughout treatment. Side-effects, which may be severe, include nausea, vomiting, and oto-, nephro- anti
citalopram A selective serotoninreuptake inhibitor (SSRI).
Dose: used in depression in single daily doses of 20 ing, increased up to 40 mg daily. Treatment for at least 6 months necessary to avoid relapse. (Cipraruil). See page 128 and Table 11.
cladribine A new agent used by specialists in hairy cell leukaemia. (Leustat).
clarithronlycin A macrolide antibiotic similar to erythromycin, but with better absorption and reduced gastrointestinal side-effects.
Dose: 250 rug twice a day for 7 days, doubled in severe infections. Care in hepatic an([ renal impairment. It may potentiate the effects of warfarin and digoxin. Should not be given with astemizole or terfenadine (risk of arrhythinias). (Khricid).
clavulanic acid An inhibitor of betalactanlase. Many penicillin-resistant organisms contain that enzyme in the cell wall, which inactivates the penicillin before it call enter the cell and exert its bacterial action. clavulanic acid inhibits such enzyme activity, and so facilitates the penetration of the antibiotic into the bacterial cell. It is used in association with amoxycillin as coamoxiclav (Augmentin) and with ticarcillin as Tinientin, in the treatment of infections due to amoxycillin-resistant bacteria.
clemastine An antihistamine used in allergic rhinitis, urticaria and allergic derniatoses.
Dose: I mg twice a day. In common with other antihistamines, it may cause drowsiness, and anticholinergic side-effects such as dryness of the mouth. H avegil). See
page 110 and Table 2.
clindamycin An antibiotic used mainly in staphylococcal bone and joint infections not responding to other drugs. It is also useful in anaerobic abdominal infections.  A serious side-effect is a potentially fatal pseudomernbranous colitis, and the drug should be withdrawn immediately if diarrhoea occurs. See vancomycin and nietronidazole.

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.