Posts Tagged ‘antihypertensive drugs’

vasodilators Traditional vasodilators used in the prophylaxis and treatment of angina include glyceryl trinitrate and other nitrates. They have a general effect on the venous system but newer and more selectively acting antihypertensive drugs are the betaadrenoceptor blocking agents represented by propranolol, and the calcium channel blocking agents such as nifedipine. Other vasodilator drugs are the alpha-adrenoceptor blocking agents (indorarnin, prazosin) and the ACE inhibitors (captopril). Cerebral vasodilators are represented by isoxsuprine. Peripheral vasodilators include cinnarizine and thymoxamine. See pages 114 & 148.
vasopressin A preparation of the blood pressure- raising and antidiuretic factors of the pituitary gland. It has been used in doses of 5-20 units twice daily by s.c. or i.m. injection in diabetes insipidus, but has been largely superseded by demopressin. (Pilressin).
vecuronitim A non-depolarizing muscle relaxant of the rocuronium type. It has a medium duration of action, with the advantage of not causing histamine release. Dose: 80-100fLgjkg1min initially, with supplementary doses as required. (Norcuron).
venlafaxine An antidepressant that inhibits the re-uptake of both serotonin and nor-adrenaline.
Dose: in depressive illness, 75 mg daily, rising if necessary after some weeks to 150 ing daily, or exceptionally to 375 mg daily. Prolonged treatment is necessary for an adequate response and reduce potential relapse. Reduced doses are given in hepatic disease and lite elderly. Care is necessary in epilepsy, and before and after morloaniine oxidase inhibator (MAGI) therapy. Many side-effects have been noted, but any skin reaction should be reported to the prescriber. (Ffcxor). See page 128 and Table 11.
Dose: 120-480 mg daily according to the condition and degree of response. In severe arrhythinias, 5-10 mg i.v. under ECG control. Contraindicated in bradycardia, heart failure and heart block. Side-effects include nausea, hypotension and heart block. It should be used with caution in a patient already receiving a betaadrenoceptor blocking agent. (Cordilox; Securon). See page 148 and Table 21.
vigabatrin A new anti-epileptic drug. GABA (a gamma aminobutyric acid) is an inhibitor of neurotransmission, and epileptic seizures may be linked with a GABA deficiency. Vigabatrin has an inhibitory action on the GABAmetabolizing enzyme, and so indirectly permits a rise in the brain level of GABA. It is used in the treatment of epilepsy not responding to other anticonvulsants. Dose: 2 g daily initially, with adjustments up to 4 g daily together with current antiepileptic therapy. Side effects are numerous, and include drowsiness, fatigue, dizziness and weight gain. Sudden withdrawal is inadvisable. (Sabril). See page 136 and Table 15.
viloxazine An antidepressant with the general action, uses and side-effects of amitriptyline, but with a reduced sedative activity. It is given in depression associated with apathy, and in the depression of epilepsy.
Dose: 150-400 mg daily. It may increase the action of phenytoin and antihypertensive agents. (Vivalan). See page 128 an(] Table 11.
vinblastine An alkaloid of periwinkle that has cytotoxic properties. It is used in the control of acute leukaemias, lymphomas and other malignant conditions, and in mycosis fungoides.
Dose: 100 ltrjkg weekly i.v., increased by 50 pg/ki; weekly, up to 500 µg/kg weekly according to response. Side-effects include myclosuppress.ion, neurotoxicity and abdominal disturbances. The drug should be handled with care as it is a tissue irritant. (Velbe). See page 122 and Table 8.
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verapamil A calcium channel blocking agent that reduces the movement ofcalciurn ions in cardiac tissues. It reduces the oxygen demand as well as the contractility of the myocardium, and it is used in angina, arrhythmias and hypertension.
vincristine A vinca alkaloid with the action and uses of vinblastine, but much less likely to cause myclodepression. It is used mainly in the treatment of acute
leukaemias in children, Hodgkin’s disease and other malignant lymphomas.

Neuromuscular side-effects may limit the dose. Other side-effects are abdominal disturbance and alopecia. The injection of the drug requires care as it is a tissue irritant. (Oncovin). See page 122 and Table 8.
vindesine A vinca alkaloid with an action similar to that of vincristine. It is used mainly in acute lyniphoblastic leukaemia in children, and in other malignant conditions not responding to treatment.
Dose: 3 nig/m` weekly by i.m. injection, subsequently increased up to 5 mg/in’ according to response. The side-effects are similar to those of other vinca alkaloids, but granulocytopenia may be a close-limiting factor. Extravasation should he avoided, as it may cause considerable local irritation. (Eldesine). See page 122 and fable R.
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vitamin D. Calciferol.
vitamin E The vitamin in the germ of wheat, rice and other grains. Deficiency States are uncommon, but may occur in cystic fibrosis and other conditions where fat absorption is impaired. It has been used empirically in many other
conditions, but its therapeutic value is questionable.
Dose: 5-15 ing daily. Now largely replaced by the synthetic form tocopherol.
vitamin K The vitamin concerned with the formation of prothrombin, and so with blood coagulation. Given as menadiol in haemorrhagic disorders, vitamin K, or phytomenadione has a similar but more rapid and sustained action. Of no value when the prothrombin level of the blood is adequate.
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vinorelbine A cytostatic drug of the vinca alkaloid type. It is used in non-small cell lung cancer and in advanced breast cancer resistant to other drugs.
Dose: 25-36 ing/inweekly by i.v.
infusion. Main side-effect is neutropenia. (Navelbine). See page 122.
vitamin A One of the vitamins obtained from fish-liver oils. A deficiency in the diet causes night-blindness, skin changes and a decreased resistance to infection. Dose: 2500-25 000 units daily.
vitamin B A group of water soluble vitamins obtained from yeast or rice polishings. The constituents include thiamine, riboflavine, nicotinic acid, pyridoxine, and small amounts of other factors.
vitamin B. Pyridoxine.
vitamin B,, Cynacobalamin. vitamin C Ascorbic acid.
warfarin A synthetic anticoagulant similar to phenindione, but with reduced side-effects and it is now the preferred drug. It is used mainly in deep-vein thrombosis and transient brain ischaernia, in doses based on the prothrombin time as
reported by the laboratory in terms of the International Normalized Ratio (INR). Dose: Pending INR report, 10 ing daily initially for up to 3 days. Haemorrhage is the main side-effect, and may require the use of phytornenadione to control the excessive response.
Whitfield’s ointment Benzoic acid 6%, salicylic acid 3%. Has keratolytic and fungicidal properties, and is used mainly for ringworm.
wool alcohols A water-in-oil emulsifying agent obtained from wool fat. It is used in many water-containing ointments, such as ointment of wool alcohols and hydrous ointment.
vitamin D The vitamin essential for the absorption of calcium and phosphorus and subsequent bone formation. Several forms of the vitamin are known, but it is used chiefly as calciferol. Vitamin D is activated in the liver and kidneys to more powerful derivatives such as calcitriol and alfacalcidol.
wool fat A pale yellow, waxy substance, also known as lanolin, obtained from sheep’s wool. It consists mainly of cholesterol-derivatives, and is a constituent of various water-in-oil emulsifying and emollient ointment bases. It may cause skin sensitization in some susceptible patients.

xamoterol A partial 0, adrenoceptor agonist with a cardiac stimulant action. It is given only in mild chronic heart failure to control exercise-induced symptoms. Dose: 400 ing daily. Side-effects are dizziness, headache and gastrointestinal disturbances. Contraindicated in severe heart failure, and care is necessary in asthmatic conditions. (Corwin). See page 141 and Table 18.
xipamide A long-acting diuretic and anti-hypertensive similar to chlorthalidone. Dose: in hypertension, 20 ing is given as a morning close: in oedematous states, 40-90 mg as a single dose, reduced later as necessary. (Diurexan). See page 148 and Table 21.
xylometazoline A sympathomimetic agent used as a nasal decongestant, and to relieve allergic conjuncfivitis as drops of 0.05-0.1%. Rebound congestion may be a side-effect.
Z
zalcitabineV An antiviral agent used in the suppressive treatment of AIDS patients who have become resistant to or have failed to respond to zidovudine therapy. Dose: 2.25 nig daily under expert supervision, as the drug has many side-effects including
., peripheral neuropathy. 0 livid).
zidovudine An antiviral agent effective against the human immunodeficiency virus (HIV) associated with the acquired immune deficiency syndrome (AIDS). It inhibits the enzyme reverse transcriptase and, by preventing the formation of viral DNIA, it inhibits viral development. Dose: 33 ing/kg4-hourly for some months. Side-effects include anaemia, neutropenia, nausea, fever and malaise. Liver-function tests are necessary during treatment. The chronic use of analgesics such as paracetamol may increase the risk of neutropenia. (Retrovir). See page 144 and “table 19.
zinc oxide A soft white powder widely used in dusting powders, ointments, pastes, etc., for its mild astringent and antiseptic properties. It is a constituent of Lassar’s paste, Unna’s paste, Calamine Lotion and similar preparations.
zinc sulphate Used as an astringent and stimulating lotion (1%) for indolent ulcers; and in conjunctivitis as eye drops (0.25%).
zinc undecenoate A white insoluble powder. Constituent of dusting powders and ointments for mycolic conditions.
zolmitriptan A serotonin receptor agonist used only in the treatment of acute migraine.
Dose: 2.5 ing as soon as possible after onset. .A second dose may be given not less than 2 hours later if symptoms persist. Vornig). See page 154 and Table 23.
zolpidem A mild hypnotic that acts by binding with a sub-group of benzodiazepine receptors. It has a rapid action, and is used in the short-term treatment of insomnia.
Dose: 10 mg. Side-effects are dizziness and gastrointestinal disturbance. (SI ilnoct). See page 152 and Table 22.
zopiclone A mild hypnotic that binds with a sub-group of benzodiazepine receptors, and may modulate the neurotransmitter GABA.
Dose: in insomnia and early awakening, 7.. —]S mg with initial doses of 3.75 mg for the elderly. A side-effect is a bitter or metallic after-taste. (Zimovane). See page 152.
zuclopenthixol A powerful tranquillizing drug with actions, uses and side-effects similar to those of chlorpromazine. It is of value in schizophrenia with agitation and aggression.
Dose: 20-30 mg or more up to 150 mg daily. For depot maintenance treatment, 100-200 mg or more by deep i.m. injection at intervals of 2-3 weeks, according to need and response. (Clopixol). See page 168.

mepacrine A synthetic antimalarial. Now replaced by chloroquine and other powerful drugs. It is used occasionally in the treatment for Giardia laynblia infections. Dose: 300 mg daily for 5-8 days.
tmeprobamate A mild tranquillizer used Ili anxiety and tension states, but its extended use may lead to dependence. Dose: 1.2-2.4 g daily. Side-effects are drowsiness, headache, gastrointestinal and visual disturbances. It has been largely replaced by benzodiazepine anxiolytics. (Equallil).
meptazinol An analgesic for the relief of moderate to severe pain. It has a more rapid and extended action than morphine, and is less likely to cause respiratory depression or induce dependence.
Dose: 800-1600 nig orally daily. In severe pain, 50-100nig by injection, repeated as required; in obstetric analgesia, 2 nig/kg. The action can be partly antagonized by naloxone. Side-effects include dizziness and nausea. (IMeptid).
rinequitisizine An antihistamine used for the symptomatic relief of allergic states such as haytever and urticaria. It is less likely to Cause sedation than sonic other antihistamines.
Dose: 10 mg daily. Side-effects may include dry mouth and blurred vision. (Prinialan). See page 110 and Table 2.
mercaptopurine A cytotoxic agent used in the treatment of acute leukaemia.
Dose: 2.5 niWkg daily. Close haernatologi,al control is essential, as the drug has .1 marked niyelosuppressive action. \.lercaptopurine is also hepatotoxic, and should be withdrawn if jaundice occurs. (Puri-Nethol). See page 122 and Table 8.
meropenem An antibiotic similar to imipenem. but more resistant to breakdown by renal enzymes, so combined use with an enzyme inhibitor is unnecessary. Dose: given by i.v. infusion in doses of 500 mg-2 g 8-hourly according to the severity of the infection. Care is necessary in hepatic disease. (Meronem).
mesalazine The active metabolite of sulphasalazine. It is not suitable for oral
use as such, but can be given as a resin-drug complex, so that the drug reaches and is released in the colon unchanged. It is used both for the acute attack and for the maintenance of remission of ulcerative colitis, particularly in patients unable to tolerate sulphasalazine.
Dose: 1.2-2.4 g daily. Side-effects include gastrointestinal disturbances, and care is necessary in patients hypersensitive to salicylates. Patients should be advised to report an), bruising, bleeding or malaise. If .a blood dyscrasia is suspected, a [)food count should be done and the drug withdrawn. Lactulose should not be used as a laxative, as it may hinder the release of the active drug. Also used as enema and suppositories. (Asacol; Pentasa; Salofalk). See page 172 and Table 32.
mesna A compound used to prevent the liaemorrhagic cystitis caused by the cytotoxic drugs cyclophosphamide and ifosfamide. The reaction is caused by the metabolite acrolein, and mesna reduces the toxicity by combining with acrolein in the urinary tract.
Dose: 20%, of that of the cytotoxic drug, and should be given at the same time by i.v. injection. Subsequent supportive doses may be given orally or by injection il - 8 hours after therapy. (Uromitexan).
mesterolone An orally active androgen with the actions and uses of testosterone. It is used in androgen deficiency and male infertility but, unlike other androgens, it does not inhibit endogenous androgen production, and is less hepatotoxic. Dose: 75-100 mg daily for sonic months. (I'm Viron).
mestranol An orally active oestrogen present in some oral contraceptive products. See page 264.
metaraminol A sympathornimetic agent that increases the blood pressure by a general constriction of the peripheral blood vessels. It is used mainly in the acute hypotension that may occur with spinal anaesthesia. It has also been used in shock, but the use of vasoconstrictors has declined, as in shock the peripheral resistance may be already high, and the use of blood volume expanders and dopamine and dubotamine is now preferred.
Dose: 15-100 mg 1)), i.v. infusion. Side-effects are tachycardia and reduced renal blood How. It is contraindicated in myocardial infarction. (Aramine).
metformin An orally active biguanide hypoglycaemic agent. Its action differs from that of the sulphonylureas, as it acts by increasing the peripheral uptake of glucose. It is used mainly in non-insulindependent diabetes not controlled by diet and sulphonylurea therapy.
Dose: 1.5-3 g daily according to need and response. Side-effects include nausea and transient diarrhoea. 11 may cause lactic acidosis and it should not be used in patients with renal impairment. (Glucophage). See page 131 and Table 13.
tmethadone A morphine-like analgesic with reduced sedative effects. Ofvalue in severe pain, and in the relief of useless cough in terminal disease.
Dose: 5-10 mg orally or by i.m. or s.c. injection, in intervals according to need. Prolonged treatment carries the risk of cumulative effects and overdose.
(Physeptone).
methenamine See hexarnine.
methionine A sulphur-containing amino acid essential for nutrition. It is used mainly in paracetamol poisoning, often with acetyl cysteine, and given within 10-12 hours.
Dose: 2.5 g 4-hourly up to a total of [0 g.
methocarbamol A skeletal muscle relaxant used in muscle injury and spasm.
Dose: 6g daily orally; 1-3 g daily by slow i.v. injection. It may cause drowsiness, dizziness and allergic rash. Contraindicated in epilepsy and myasthenia gravis. (Robaxin).
methohexitone A short-acting i.v. anaesthetic similar to thiopentone. It is used mainly for the induction and maintenance of anaesthesia for short operative procedures, when the quick recovery may be an advantage. (Brietal).
methotrexate A cytotoxic agent that acts by inhibiting the synthesis of purines, and so indirectly interferes with cell proliferation. It is used chiefly for maintenance therapy in the remission of acute lymphoblastic leukaemia in children, but it has been used in choriocarcinoma as well as some lymphomas and solid tumours.
Dose: in children, I5 mg/in' weekly. It is sometimes effective in resistant psoriasis, and is given in oral doses of 10-25 nig weekly under specialist supervision. It is occasionally used in severe rheumatoid arthritis not responding to other treatment in doses of 7.5 mg once weekly. Side-effects are those of gastrointestinal toxicity, niyelodepression, rash and cirrhosis. Blood counts and liver function tests during treatment are essential. Cough and dyspnea may indicate pulmonary toxicity. Aspirin and non-steroidal anti-inflaniniatory drugs (NSAIDs) should be avoided, as they delay the excretion of methotrexate and increase its toxicity. See page 122 and Table 8.
methotrimeprazine An antipsychotic agent of the chlorpromazine type, with similar actions, Uses and side-effects. It is used in schizophrenia when a sedative effect is also required.
Dose: 25 -50 mg daily, but much larger doses, up to 1 g daily, may be required, particularly for bedfast patients. It is of value as an adjunct to other therapy in terminal illness and is sometimes given by continuous s.c. infusion in doses of 25-200 ing over 24 hours. Postural hypotension may occur in elderly ambulant patients. (Nozinan). See page 168 and Table 30.
methoxamine A sympathomimetic agent that increases the blood pressure by constriction of the peripheral vessels. It is used in the hypotension following spinal anaesthesia; to correct an excessive response to antihypertensive drugs; and to arrest supraventricular tachycardia. Dose: 5-20 mg by i.m. injection; 5-10 mg by slow i.v. injection. Care is necessary in preexisting hypertension and cardiov.iwular disease (Vasoxine).
methyl cellulose A derivative of cellulose that is used as an emulsifying agent and bulk laxative.
Dose: 1.5-6g with water, but not at night. It is sometimes given in diarrhoea, with a minimum amount of water.
methyl salicylate A pale yellow liquid with a characteristic odour. It has long been used as wintergreen liniment and ointment for the local relief of muscle pain and rheumatic conditions, but is now less popular.

methylated spirit Alcohol containing 5% of wood naphtha. Used for skin preparation and alcoholic applications. The methylated spirit used domestically differs, and is coloured violet to indicate its unsuitability for medicinal use.
methylcysteine A sputum-liquefier claimed to be of value in respiratory conditions where the sputum is viscid. Dose: 600 ing daily. (Visclair).
! Met
other pressor amines. It is used mainly in the preoperative control of adrenaline-producing tumours (pliaeochrornocytoma), and in the long-term treatment of patients unsuitable for surgery.
Dose: I g daily initially, increased if necessary up t(') 4g daily. An adequate fluid intake is essential. Side-effects include sedation, which may be marked initially, diarrhoea, which maybe severe, depression and confusion. (Dernser).
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methyidopa A centrally acting antihypertensive drug, usually given together with a diuretic. It has the advantage of being relatively safe in asthma, heart failure and pregnancy.
Dose: 750 ing-3 g daily; 250-500 mg by i.v. infusion. Side-effects are drowsiness, depression and diarrhoea. A systemic lupus crytheinatostis-like syndrome may also occur, and active liver disease is a contraindication. (Alcloinet). See page 148 an(] Table 21.
tmethylphenidate A central stimulant used occasionally under strict supervision for the treatment of hyperactive children. Dose: 5-10 mg daily. Witalin).
metoclopramide A stimulant of gastric and small intestine transport. It is used in the treatment of nausea and vomiting generally, including that induced by drugs or migraine, in non-ulcer dyspepsia, and in accelerating the passage of a barium meal.
Dose: 15-30 ing daily orally or by Lin. or i.v. injection. A single dose of 10-20 mg is given by injection 10 minutes before radiological examination. Side-effects include extra-pyramidal reactions, facial sprints and oculogyric crises, mainly in voting persons, and it is best avoided in patient., under 20 years of age. (Maxolon). Some long-acting products are also available. See page 158 and Table 25.
tmethylphenobarbitone An anticonvulsant with the actions, uses and side-effects of phenobarbitone.
Dose: in epilepsy, 100-600 ing daily. (Prominal). See page 136 and Table 15.
methylprednisolone A corticosteroid with the actions, uses and side-effects of prednisolone, and given in similar doses. (Medrone).
methysergide A synthetic drug related to ergonicirine and used in the prevention of severe and recurrent migraine not responding to other drugs.
Dose: 2-6 ing daily. It is also given fur the symptomatic treatment of the carcinoid syndrome in (loses of 12-20 ing daily. Mcthvsergide has many side-effects, including retroperitoneal and cardiac fibrosis, and its use requires expert supervision. (Des-A-ril)-See page 154 and] able 23.
metipranolol A beta-adrenoceptor blocking agent used as eye drops 0.1-0.6% for the treatment of chronic glaucoma.
metirosine An enzyme inhibitor that interferes with the synthesis of adrenaline and
metolazone A diuretic with the actions, uses and side-effects of bendrofluazide.
Dose: in hypertension, 5 mg daily I p
initially; in oedematous statcs,5-20ingor more daily may be given. The diuresis is increased by combined treatment with a loop diuretic such as ffl,lsemide, but monitoring of the response is necessary. (NIctinex). See page 148 and Table 21.
metoprolol A beta-blocking agent used in the control of angina, but also of value in hypertension and the prophylaxis of migraine.
Dose: in angina, 100-300 mg daily; in hypertension, 100-400 ing daily; in migraine prophylaxis and thyrotoxicosis 200 ing daily. It is occasionally given by slow i.v. injection in acute cardiac arrhythinias; dose 1-2 nighnin tip to a total of 10-15 mg. Care is necessary in heart block, bradycardia and pulmonary disease. (Betaloc; Lopresor). See page 114 and Table 4.
metriphonate An organophosphorus schistosornicide, but used only in infections of the hookworm Schistosonia haemobitim, which is found in the genitourinary veins.

A-Z Principal Drugs (antidepressants - astemizole)
antidepressants The drugs used in the treatment of depression fall into two main groups, the so-called tricyclic antidepressants and the monoamine oxidase inhibitors (MA01s). (Unrelated drugs include lithium carbonate, used only for the prophylaxis and treatment of manic depressive illness.) The tricyclic group, which also includes sonic other compounds with a similar action, appear to act by blocking the neuronal uptake of central transmitters such as noradrenaline and serotonin. They are more widely used than the MAOIs because they are more generally effective, and interact less extensively with other drugs and certain foods. The tricyclic drugs are widely used in endogenous depression, particularly when sleep disturbances are present, but the onset of action is slow, and improvement may not commence until after 2-4 weeks of treatment. Extended therapy is usually required to avoid the risk of a relapse, and patients should be advised accordingly. Sonic tricyclic antidepressants, such as amitriptyline, have a sedative action of value when anxiety is a complicating factor, whereas a less sedating drug such as imipramine may be useful in patients exhibiting apathy and withdrawal. Some of the side-effects, such as dryness of the mouth, are linked with their anti-
cholinergic activity, but tolerance may develop with continued treatment. They also influence the cardio-vascular system and may cause arrhythmias, tachycardia and hypotension, and may interfere with the action of some antihypertensive drugs, although the response to beta-blocking agents is unaffected. Care is necessary in cardiac disease, and with the elderly initial doses should be low. The use of tricyclic antidepressants in epileptic patients may result in a lowering of the convulsive threshold. See page 128 and Table 11.
antidiabetic agents Diabetes mellitus is a deficiency disease due to a lack of insulin, and is characterized by an excessive level of glucose in the blood and urine. Treatment is either replacement therapy with daily injection of insulin, or orally by hypoglycaemic agents such as chlorpropamide. Such agents act by stimulating insulin secretion and release by the beta-cells of the pancreas, and are ineffective in the absence of such cells. See page 132 and Tables 12 & 13.
anti-D(Rh.) immunoglobulin An ininiurioglobulin that is given to a rhesus-negative mother to prevent her forming anti-bodies against fetal rhesus-positive cells which may pass into the maternal circulation during childbirth or abortion and which, in a later pregnancy, could cause haemolytic disease.
Dose: 504) units Lin. within 60-72 hours of delivery or abortion. Doses of 1250 units are given prophylactically. It is of no value it’given after anti-D antibodies have been formed. The inimunoglobulin has also been given after the transfusion of rhesus-incompatible blood. (Partobulin).
antiemetics Nausea and vomiting may be due to several causes, including stimulation of the chemoreceptor trigger zone in the reticular formation of the brain. Man), antiemetics have some degree of central activity, and in some cases their action may be mediated by blocking the effects of dopamine on the trigger zone. Effective drugs include some antihistamines and sonic phenothiazine-based tranquillizers such as prochlorperazine. The alkaloid hyoscine is widely used in travel sickness. More powerful drugs such as domperidone, metoclopramide, nabilone and ondansetron, are of value in the control of the severe nausea and vomiting induced by cytotoxic drugs. The use of antiemetics in early pregnancy requires great care, and is seldom essential.
antiepileptics See anticonvulsants, page 136 and’] able 15.
antihistamines Drugs such as promethazine are of value in conditions associated with the release of histamine from mast cells, such as hayfever, rhinitis, urticaria, pruritus, insect bites and stings. They are also useful in drug allergies. Some antihistamines also have antienietic properties, and are useful in travel sickness. Although all antihistamines have the same basic action, the degree and duration of response and the severity of side-effects may vary. Some antihistamines pass easily into the central nervous system arid are more likely to cause drowsiness. Others may have reduced anticholinergic properties, and cause less dryness of the mouth and blurring of vision. Care is necessary in epilepsy, glaucoma, hepatic disease or prostatic enlargement. See page 110 and Table 2.

antihypertensive agents See page 148 and Table 2 1.
anti-inflammatory agents See non-steroidal anti-inflammatory drugs (NSAIDS) and page 165 and Table 29.
antimetabolites Cytotoxic drugs that appear to act by combining irreversibly with cell enzymes, and so prevent cell division. Methotrexate and mercaptopurine are examples. See page 122 and Table 8.
dermatology and pruritus as oily calamine lotion. Arachis oil enema is used to soften impacted faeces.
argipressin A synthetic form of vasopressin.
artificial tears Some chronic sore eye con clitions may occur in rheumatoid arthritis, and may be due to tear deficiency. Solutions of itypromellose or polyvinylalcohol, sometimes referred to as’artificial tears’, are useful as a bland lubricant to replace the tear deficiency. (Isopto; Hypotears).
antimuscarinic agents See anticholinergic agent” page 160 and Table 26.
antineoplastic agents Anti-cancer drugs. See page 122 and ‘rabic 8.
antipsychotic agents See pages 117 & 1(,8, and Tables 5 & 30.
antitetanus immunoglobulin aulloglobulin obtained from plasma is used in injured patients who have not previously been immunized, and when tetanus is a definite risk. Dose: 250 units jan. A course of tetanus vaccine should also be commenced,
antitubercular agents See rifampicin, page 170 and I able 31.
antiviral agents See page 144 and Table 19.
anxiolytics See page H 7 and Table 5.
apomorphine A morphine derivative formerly used as a powerful emetic, but now considered to be too toxic. Occasionally used in the hospital treatment of parkinsonism. (Britaject).
apraclorildine A clonidine derivative used as eye drops I 9A, to control intraocular
pressure during ophthalmic surgery. Some absorption may occur, so care is necessary in severe cardiovascular disease. (lopidine).
aprotinin An inhibitor of the proteolytic enzyme plasmin, obtained from bovine lung tissue. It is used in the severe haemorrhage due to hyperplasminaemia.
Dose: 500 000-1 000 000 units by i.v. infu.ioll. (Trasylol).
arachis oil Groundnut or peanut oil. It has
emollient properties, and is used in
ascorbic acid (vitamin C) Present in many citrus fruits. Deficiency is not uncommon in the elderly receiving inadequate diets. Severe deficiency causes scurvy, once the bane of seafarers.
Dose: for prophylaxis 25-75 mg daily; therapeutic dose 200-500 mg daily. Doses of 4 g daily are given for acidification of the urine. Claims that vitamin C prevents colds are unproven.
asparaginase Crisantaspase. See page 122 and Table 8.
aspirin (acetylsalicylic acid) Widely used as a mild analgesic and anti-inflammatory agent, often in association with other drugs such as paracetamol and codeine. Dose: 1.2-4 g daily, but in acute rheumatoid conditions doses of 4-8 g daily have been given. Long-term treatment with (loses of 75 mg daily are given liar the prophylaxis of cardiovascular disease. Side-effects include gastric irritation with some blood loss, hyperventilation, and bonitos, with the risk of deafness, may occur with high doses. Aspirin may cause rash and bronchospasm in asthmatic and other sensitive patients. As aspirin is now thought to be associated with Reye’s syndrome, the drug should not be given to children under 12 years of age unless specifically indicated. Aspirin may increase the effects of certain hypoglycaemic and anticoagulant drugs.
astemizole An antihistamine with an extended action and reduced sedative effects.
Dose: Wring once daily before food, and must not be exceeded. Higher doses may cause cardiotoxic side-effects such as ventricular tachycardia. Arrhythmias may follow combined treatment with many other drugs. (Hismanol; Pollen-ese). See page 110 and Table 2.