Posts Tagged ‘sedative effect’

Generic Name
Clonidine (KLAH-nih-dene)
Brand Names
Catapres-TTS-2
Catapres-TTS-1    Catapres-TTS-3
Type of Drug
Alpha receptor stimulant.
Prescribed For
High blood pressure, including hypertensive emergency (diastolic blood pressure over 120); also used for excess sweating, childhood growth delay, attention-deficit hyperactivity disorder (ADHD), Tourette’s syndrome, restless leg syndrome, schizophrenic psychosis, migraine, ulcerative colitis, painful or difficult menstruation, hot flashes related to menopause, diagnosis of pheochromocytoma (adrenal-gland tumor), kidney poisoning associated with cyclosporine, diabetic diarrhea, smoking cessation, methadone and opiate detoxification, withdrawal from alcohol and benzodiazepines such as Valium, nerve pain following herpes attack, and allergic reactions in the presence of asthma triggered by external sources.
General Information
Clonidine stimulates nerve endings in the brain called alphaadrenergic receptors. It reduces blood pressure by dilating (widening) blood vessels. Clonidine works quickly, decreasing blood pressure within 1 hour. The other uses of clonidine relate to its stimulation of alpha receptors in the body.
Cautions and Warnings
Do not take clonidine if you are allergic or sensitive to any of its ingredients.
People who have had a stroke or recent heart attack or who have cardiac insufficiency or chronic kidney failure should avoid taking clonidine.
Some people develop a tolerance of their clonidine dosage. If this happens, your blood pressure may increase and your doctor may prescribe a higher dose.
Never stop taking clonidine without your doctor’s knowledge. If you abruptly stop taking clonidine, you may experience an unusual increase in blood pressure accompanied by agitation, headache, nervousness, and severe reactions, possibly death. Restarting clonidine therapy or taking another antihypertensive can reverse these effects.
Clonidine may cause degeneration of the    See your eye doctor for regular GheCk Ups lfiyou are taking this drug.
); you require surgery, your doctor will continue your clonidine therapy until about 4 hours before surgery and resume it as soon as possible afterward.
People who develop skin sensitivity (symptoms include rash, itching, and swelling) to Catapres-TTS, the transdermal patch form of clonidine, may experience the same reactions with oral clonidine.
Possible Side Effects
Tablets
♦    Most common: dry mouth, drowsiness, dizziness, constipation, and sedation.
♦    Common: headache and fatigue. These effects tend to diminish within 4-6 weeks.
•    Less common: appetite loss, swelling or pain in the glands of the throat, nausea, vomiting, weight gain, blood-sugar elevation, breast pain or enlargement, worsening of congestive heart failure, heart palpitations, rapid heartbeat, painful blood-vessel spasm, abnormal heart rhythms, electrocardiogram changes, feeling unwell, changes in dream patterns, nightmares, difficulty sleeping, hallucinations, delirium, anxiety, depression, nervousness, restlessness, rash, hives, thinning or loss of scalp hair, difficult or painful urination, nighttime urination, retaining urine, decrease or loss of sex drive, weakness, muscle or joint pain, leg cramps, increased alcohol sensitivity, dryness and burning of the eyes, dry nose, loss of color, and fever.
Transdermal Patch
✓    Most common: dry mouth and drowsiness.
✓    Less common: constipation, nausea, changes in sense of taste, dry throat, fatigue, headache, lethargy, changes in sleep patterns, nervousness, dizziness, impotence, sexual difficulties, and mild skin reactions including itching, swelling, contact dermatitis, discoloration, burning, peeling, throbbing, white patches, and generalized rash. Rashes of the face and tongue have also occurred but cannot be specifically tied to transdermal clonidine.
Drug Interactions
•    Combining clonidine and a beta-adrenergic blocker may increase the severity of a drug-withdrawal reaction and rebound high MW pressure. This reaction may be very serious.
•    Combining verapamil and clonidine may lead to very low blood pressure and atrioventricular (AV) block (abnormality in heartbeat patterns). This reaction may be very serious.
O    Avoid alcohol, barbiturates, and sedatives because they increase the depressive effects of clonidine.
•    Tricyclic and other antidepressants, appetite suppressants, estrogens, stimulants, indomethacin and other nonsteroidal anti-inflammatory drugs (NSAIDs), and prazosin may counteract the effects of clonidine.
•    clonidine may reduce the therapeutic effects of levadopa +
carbidopa.
Food Interactions
The tablets are best taken on an empty stomach but may be taken with food if they upset your stomach.
Usual Dose
Tablets
Adult: high blood pressure-100 mcg twice a day to start; may be raised by 100 mcg a day until maximum control is achieved. Take no more than 2400 mcg a day. Other uses-100-goo mcg a day, or up to 0.8 mcg per lb. of body weight in divided doses. Seniors should start with a lower dose and increase more slowly.
Child: 50-400 mcg orally twice a day.
Transdermal Patch
Adult: 100 mcg delivered daily from a patch applied once every 7 days. Up to two 300-mcg patches may be needed to control blood pressure. Transdermal dosage exceeding 600 mcg a day has not been shown to increase effectiveness.
Child: not recommended.
Overdosage
Symptoms of overdose are slow heartbeat, central- nervous-system depression, very slow breathing, low body temperature, pinpoint pupils, seizures, lethargy, agitation, irritability, nausea, vomiting, abnormal heart rhythms, mild increases in blood pressure followed by a rapid drop in blood pressure, dizziness, weakness, loss of reflexes, and vomiting. Victims should be taken to a hospital emergency room immediately. ALWAYS bring the prescription bottle or container.
Special Information
Gk’3t1161)e causes drowsiness in about 1/3 of people who take it. Be extremely careful while driving or performing any task that requires concentration. This effect is prominent during the first few weeks of clonidine therapy and then tends to decrease.
Do not take over-the-counter cough and cold medications unless directed by your doctor.
Call your doctor it you become depressed or have vivid dreams or nightmares while taking clonidine, or if you develop swelling in your feet or legs, paleness or coldness in your fingertips or toes, or any persistent or bothersome side effect.
Apply the transdermal patch to a hairless area of skin such as the upper arm or torso. Use a different skin site each time. If the patch becomes loose, apply the supplied adhesive directly over it. If the patch falls off before 7 days are up, apply a new one. Do not remove the patch while bathing.
If you forget a dose of oral clonidine, take it as soon as possible and then go back to your regular schedule. If you miss 2 or more consecutive doses, consult your doctor; missed doses may cause blood pressure increases and severe adverse effects. Do not take a double dose.
Special Populations
Pregnancy/Breast-feeding: Clonidine passes into the fetal bloodstream. Animal studies show that clonidine may damage the fetus in doses as low as 1/3 the maximum dose. When this drug is considered crucial by your doctor, its potential benefits must be carefully weighed against its risks.
Clonidine passes into breast milk. Nursing mothers who must take this drug should use infant formula.
Seniors: Seniors are more susceptible to the effects of this drug and should begin with lower doses.

Generic Name
Clopidogrel (kloe-PID-oe-grel) nQ
Brand Name  Plavix
Type lul Drug Antiplatelet.
Prescribed For
Heart attack and stroke prevention; also used for blood thinning after placement of a vascular stent.
General Information
Artery-clogging blood clots are often the cause of heart attacks and strokes. clopidogrel reduces the risk of both by helping prevent blood-clot formation. This drug thins the blood by making platelets—the cells that aggregate to form clots—less “sticky.” It starts working in as little as 2 hours after taking a single tablet. The drug’s blood-thinning effect lasts until inactivated platelets are replaced by the body. Studies suggest that clopidogrel is more effective than aspirin in preventing heart attack and stroke in people at risk. People taking clopidogrel after scent surgery usually take it for a relatively short period. Those taking it to prevent a heart attack or stroke must take it for life.
Cautions and Warnings
Do not take clopidogrel if you are allergic or sensitive to any of its ingredients or to ticlopidine, a related antiplatelet. These drugs can rarely cause a rapid drop in white-blood-cell count.
People with bleeding ulcers, brain hemorrhages, or other bleeding problems should use clopidogrel with caution.
Thrombotic thrombocytopenic purpura (TTP) is a rare but serious complication of clopidogrel, sometimes reported after less than 2 weeks of treatment. See your doctor right away if you develop a sudden fever, unusual bruising, nosebleeds, bleeding gums, or any other unusual symptoms. TTP reduces your platelet count, interfering with blood clotting, and affects white-blood-cell count.
People with liver problems should use clopidogrel with caution.
Possible Side Effects
✓    Most common: rash and other skin problems.
✓    Common: chest pain, accidents, flu-like symptoms, pain, headache, dizziness, abdominal pain, upset stomach, joint pain, back pain, black-and-blue marks, and respiratory infection.
✓    Less common: tiredness, Swollen arms or legs, high blood pressure, diarrhea, nausea, bleeding, nosebleeds, breathing difficulties, runny nose, coughing, bronchitis, high blood cholesterol, urinary infection, and depression.
✓    Rare: bleeding in the brain and stomach ulcer. Contact your doctor if you experience any side effect not listed above.
Drug Interactions
•    Clopidogrel may interfere with the body’s ability to break down fluvastatin, nonsteroidal anti-inflammatory drugs (NSAIDs), phenytoin, tamoxifen, tolbutamide, torsamide, and
warfann.
•    Combining clopidogrel and NSAIDs may increase blood loss and bleeding in the stomach and intestines.
•    Do not combine clopidogrel and other antiplatelet drugs or
the anticoagulant (blood thinner) warfarin unless you are
under your doctor’s direct supervision. This interaction may
prevent normal blood clotting and lead to severe bleeding
problems.
Food Interactions
Clopidogrel may be taken without regard to food or meals.
Usual Dose
Adult: 75 mg a day.
Overdosage
Little is known about the effects of clopidogrel overdose aside from reduced blood clotting. Overdose victims should be taken to a hospital emergency room. ALWAYS bring the prescription bottle or container.
Special Information
Minor cuts may take longer to stop bleeding during treatment with clopidogrel. If you are having surgery, make sure your doctor knows you are taking clopidogrel. You may have to stop taking the drug I week before surgery.
If you forget a dose, take it as soon as you remember. If it is almost time for your next dose, skip the forgotten dose and continue with your regular schedule.
Special Populations
Pregnancy/Breast-feeding: The safety of using clopidogrel during pregnancy is not known. Other antiplatelet drugs, tike aspirin, are not used during pregnancy due to their possible effects on Mrjlher and fetus. When this drug is considered crucial by your doctor, its benefits must be carefully weighed against its risks.
Clopidogrel may pass into breast milk. Nursing mothers who must take this drug should use infant formula.
Seniors: Seniors may take this drug without special precaution.

Generic Name
Clorazepate (klor-AZ-uh-pate) 99
Brand Names
Gen-Xene    Tranxene-SD
Tranxene    Tranxene T-Tab
Type of Drug
Benzodiazepine sedative.
Prescribed For
Anxiety, tension, fatigue, and agitation; symptoms of acute alcohol withdrawal; partial seizures; also prescribed for irritable bowel syndrome and panic attacks.
General Information
Clorazepate dipotassium is a benzodiazepine. Benzodiazepines directly affect the brain. They can relax you and make you more tranquil or sleepier, or they can slow nervous system transmissions in such a way as to act as an anticonvulsant. Many doctors prefer benzodiazepines to other drugs that can be used to similar effect because they tend to be safer, have fewer side effects, and usually work as well, if not better.
Cautions and Warnings
Do not take clorazepate if you are allergic or sensitive to any of its ingredients or to another benzodiazepine drug, including clonazepam.
Clorazepate can aggravate narrow-angle glaucoma, but you may take it if you have open-angle glaucoma and are receiving therapy for it.
Other conditions in which clorazepate should be avoided are: severe depression, severe lung disease, sleep apnea (intermittent cessation of breathing during sleep), liver disease, drunkenness, and kidney diseaap_, to inOn of these conditions, the qq)NSSvve effects of clorazepate may be enhanced or could be detrimental to your overall condition.
Clorazepate should not be taken by psychotic patients because it is not effective for them and can trigger unusual excitement, stimulation, and rage.
Clorazepate is not intended to be used for more than 3-4 months at a time. Your doctor should reassess your condition before continuing your prescription beyond that time.
Clorazepate may be addictive. It should be used with caution in people with a history of drug dependence.
Drug withdrawal may develop if you stop taking it after as few as 4 weeks of regular use but is more likely after longer use. It may start with anxiety and progress to tingling in the hands or feet, sensitivity to bright light, sleep disturbances, cramps, tremors, muscle tension or twitching, poor concentration, flu-like symptoms, fatigue, appetite loss, sweating, and changes in mental state. Your dosage should always be reduced gradually to prevent drug withdrawal symptoms.
Possible Side Effects
Weakness and confusion may occur, especially in seniors and in those who are more sickly.
✓    Most common: mild drowsiness during the first few days of therapy.
✓    Less common: confusion, depression, lethargy, disorientation, headache, inactivity, slurred speech, stupor, dizziness, tremors, constipation, dry mouth, nausea, inability to control urination, sexual difficulties, irregular menstrual cycle, changes in heart rhythm, low blood pressure, fluid retention, blurred or double vision, itching, rash, hiccups, nervousness, inability to fall asleep, and occasional liver and kidney dysfunction. If you have any of these symptoms, stop taking the medicine and contact your doctor immediately.
✓    Rare: Rare side effects can affect your heart, stomach and intestines, urinary tract, blood, muscles and joints. Contact your doctor if you experience any side effects not listed above.
Drug Interactions
•    Clorazepate is a central-nervous-system depressant. Don’t mix it with alcohol, other sedatives, narcotics, barbiturates, monoamine oxidase inhibitor and other antidepressants, and antihistamines. Taking Clorazepate with these drugs may result in excessive depression, tiredness, sleepiness, breathing difficulties, or related symptoms.
•    Smoking may reduce clorazepate’s effectiveness by in-
creasing the rate at which it is broken down by the body.
•    Clorazepate’s effects may be prolonged when it is mixed with cimetidine, contraceptive drugs, disulfiram, fluoxetine, isoniazid, ketoconazole, metoprolol, probenecid, propoxyphene, propranolol, rifampin, or valproic acid. Theophylline may reduce clorazepate’s sedative effects.
•    If you take antacids, separate them from your clorazepate dose by at least 1 hour to prevent them from interfering with the absorption of clorazepate into the bloodstream.
•    Clorazepate may increase blood levels of digoxin and the chances of digoxin toxicity.
•    The effect of levodopa + carbidopa may be decreased if it is taken together with clorazepate.
•    Combining clorazepate with phenytoin may increase phenytoin blood concentrations and the chances of phenytoin toxicity.
Food Interactions
Clorazepate is best taken on an empty stomach, but it may be taken with food if it upsets your stomach.
Usual Dose
Immediate-Release
Adult and Child (age 9 and over): 15-60 mg daily. The average dose is 30 mg in divided quantities, but dosage must be adjusted to individual response for maximum effect. Maximum recommended daily dose is 90 mg. For treatment of anxiety, clorazepate may be taken as a single dose at bedtime.
Child (under age 9): not recommended.
Sustained-Release
Adult: The sustained-release form of clorazepate may be given as a single dose, either 11.25 or 22.5 mg, once every 24 hours. Sustained-release tablets are not recommended for the initial dosage.
Child: not recommended.
Overdosage
Symptoms of overdose are confusion, sleepiness, poor coordination, lack of response to pain such as a pin prick, loss of reflexes, shallow breathing, low blood pressure, and coma. The victim should be taken to a hospital emergency room. ALWAYS bring the prescription bottle or container.
Special Information
Clorazepate can cause tiredness, drowsiness, inability to concentrate, or similar symptoms. Be careful if you are driving, operating machinery, or performing other activities that require concentration.
People taking clorazepate for more than 3 or 4 months at a time may develop drug withdrawal reactions if the medication is stopped suddenly (see “Cautions and Warnings”). Do not stop taking clorazepate or increase or decrease your dosage without first consulting your doctor.
If you forget a dose of clorazepate, take it as soon as you remember. If it is almost time for your next dose, skip the dose you forgot and continue with your regular schedule. Do not take a double dose.
Special Populations
Pregnancy/Breast-feeding: Clorazepate may cause birth defects if taken during the first 3 months of pregnancy. Avoid this drug if you are or might be pregnant.
Clorazepate may pass into breast milk. Nursing mothers who must take clorazepate should use infant formula.
Seniors: Seniors, especially those with liver or kidney disease, are more sensitive to the effects of clorazepate and generally require smaller doses to achieve the same effect.

cephamandole A cephalosporin more resistant to inactivation by penicillinases. It is of value in serious infections resistant to other antibiotics.
Dose: 2-12 g daily by i.m. or i.v. injection. : Kellidol). See page 248 and Table 34.
cephazolin A cephalosporin with the
general properties of the group.
Dose: 1-12 g daily by injection. (Kefzol). See page 248 and Table 34.
cephradine A cephalosporin active orally as well as by injection.
Dose: 1-2 g orally daily; in severe infeclions 2–8g daily by injection. (Velosef). See page 248 .
certoparin A low molecular weight form of heparin. Used in prophylaxis of venous thromboembolism.
Dose: 3000 units once a day by s.c. injection (1-2 hours before surgery) for 7-10 days. (Alphaparin). See enoxaparin.
cetirizine A slower-acting antihistamine with reduced sedative effects, as it does not pass the blood-brain barrier to any extent. The anti-cholinergic side-effects are also reduced.
Dose: 10 nigat night. (’Lirtels). See page 110 and Table 2.
cetrinnide A detergent with some antiseptic properties. It is used chiefly in association with chlorhexidine.
charcoal Activated charcoal is a powerful adsorbent, and is used in the treatment of overdose or poisoning by many toxic drugs by preventing further absorption. Dose: 50g orally. It is also used in the charcoal - haenioperfusion system to promote elimination from the circulation of sonic already absorbed poisons. Charcoal has also been used as impregnated dressings to deodorize foul smelling wounds and ulcers,
chenodeoxycholic acid A bile acid
derivative that has it solvent action on cholesterol-containing gallstones, and it is useful when surgical removal of the stones is contraindicated.
Dose: I g once daily, but prolonged treatment is necessary. Side-effects are diarrhoea and pruritus, and ursodcoxycholic acid, which has fewer side-effects, is often preferred. Chenodeoxycholic acid is not suitable for the dissolution of radio-opaque gallstones. (Chendol; Chenofalk).
chloral hydrate A water-soluble hypnotic with a rapid action that is useful in the treatment of insomnia in children and the elderly.
Dose:    g. It must be given well-diluted to reduce the gastric irritant side-effects, and is contraindicated in gastritis, and severe renal, hepatic and cardiac disease. (Notre). Chloral betaine (Well-dorm) is a less irritant alternative. See page 152 and Table 22.
chlorambucil An orally active cytotoxic drug used mainly in the treatment of lymphomas and chronic lymphocytic leukaemia.
Dose: 100-200 pgfkg daily for 4-8 weeks. It k sometimes used as an immunosuppressant in the treatment of rheumatoid arthritis in doses of 2.5-7.5 mg daily. Chloranibucil is generally well tolerated, [)of [)one marrow depression may occur, and haematological control during treatment is essential. (Leukeran). See page 122 and Table 8.
chloramphenicol A wide-range, orally active antibiotic but now used only in life-threatening infections where other drugs arc unsuitable.
Dose: 2g daily orally, but in severe infections, -So niglkg daily by i.v. injection. Care is necessary when giving chloramphenicolo infants as it may cause so-called ‘grey syndrome’. Side-effects include nausea, neuritis and aplastic anaemia. Chloromycetin is also used locally in skin, eye and ear infections. (Chloromycetin; Kcinicetine).
chlordiazepoxide A benzodiazepinc used mainly in [tic short-term treatment of anxiety and alcoholism.
Dose: 30 mg daily, increased in severe anxiety up to 100 mg daily, with half closes fix elderly patients. Withdrawal of treatment should be gradual to avoid rebound effects. Side-effects include dizziness, drowsiness and ataxia. Prolonged use carries the risk of dependence. (Librium).

chlorhexidine An antiseptic of high potency and a wide range of activity, although it is ineffective against spores and viruses. For preoperative skin preparation, a 0.5% solution in alcohol is often used; an aqueous solution (0.05%) is for general topical application. Chlorhexidine is also used as a  solution for bladder irrigation. A general purpose cream and an obstetric cream are also available. Solutions of chlorhexidine may become contaminated with Pseudomonas, and all aqueous solutions should he sterilized. (1-libitane).
irreversible retinal damage. Other side-effects are gastrointestinal disturbances, rash and prutiros. (Axioclor,). Swe page 16.3.
chlorothiazide The first of the thiazide diuretics, now largely replaced by bendrofluazide and similar drugs. Dose: 1 -2 g daily in oedematous states; 0.i-1 g daily in hypertension. Potassium supplements may be necessary with extended treatment. (Saltiric). See page 148 and Table 21.
29
chlormethiazole A sedative with anticonvul’ant properties.
Dose: in severe insomnia in the elderly, 200-400nigorally; in alcohol withdrawal conditions, 400-800 mg initially, reduced and withdrawn over a 9-day period. It may also be given by i.v. infusion as a 0.8% solution. Chlonnethiazole has also been given by injection in status epilepticus and the toxaemia of pregnancy in doses according to need and response. Side-effects are sneezing, gastrointestinal disturbances and headache. (Heminevrit) See page 136 and Table Ii.
chloroform Once widely used as a general anaesthetic, but now obsolete. Used as chloroform -water in mixtures as a preservative and flavouring agent, and for its carminative effects.
chloroquine An antimalarial drug used for both prophylaxis and treatment of benign and malignant tertian malaria. It should be noted that chloroquine- resistant strains of Plasmodiunifialciparurn are becoming increasingly common, and a return to treatment with quinine may be necessary. Dose: adult prophylaxis, 300nig once a week; (Or treatment of an attack of malaria, oWnig initially followed by 300mg daily for 2-3 days. Seriously ill or vomiting patients should be given 2(XI-300 ing by Lin. or slow i.v. injection, repeated once ifncccssary L)cfi)rc oral treatment can be tolerated. Other dosage schemes are also in use, and for details reference should be made to standard works on the treatment of malaria. It has also been used in hepatic anioebiasis, but nietronidazole is now often preferred. Chloroquinc also has an action in rheumatoid inflammatory conditions similar to that of penicillamine, dose: 150 mg daily after food. Such use requires care, as extended therapy is necessary, and the drug may cause corneal opacity and
chloroxylenol A general purpose antiseptic present in some popular products. Of no value against Pseudornonas. aeruginosa or Proteus.
chlorpheniramine An antihistamine with the action, uses and side-effects of the group, including drowsiness.
Dose: 16-24 mg daily: 10-20 mg by Lin. or .c. injection as required. (Piriton). See page 110 and Table 2.
chlorpromazine A powerful tranquillizer or antipsycholic agent with a wide range of activity on the central nervous system. It is widely used in the treatment of schizophrenia and other psychoses, in agitation and tension, and the management of refractory patients. It is also effective as an antienietic in terminal illness; in the short-term treatment of severe anxiety; and for the control of intractable hiccup.
Dose: initially 75 mg orally daily, slowly increased as required. In psychotic states, Lip to I g daily. Single doses of 25-50 mg may be given by deep imi. injection in acute conditions. Suppositories of 100 mg are also available. Side-effects include extrapyramidal and anticholinergic symptoms, drowsiness, hypotension, weight gain, rash, jaundice and haemolytic anaemia. prolonged use may cause pigmentation of the skin and eyes. Care is necessary in hepatic and renal dysfunction. Skin sensitization may occur after Contact With solutions of chlorpromazine. Margactil). See page 168 and’I'able 30.
chlorpropamide A long-acting hypoglycaemic agent of the sulphonylurea type. It is effective only if some insulin-secreting cells are still functional. It is used mainly in mild diabetes mellitus occurring in middle-aged patients not responding to dietary control. Its long action makes it unsuitable for elderly diabetics.

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.