Muscle-relaxant Drugs: From 1 Different Sources
A group of drugs used to relieve muscle spasm and spasticity. Muscle-relaxant drugs are used mainly in the treatment of nervoussystem disorders such as multiple sclerosis and painful muscular conditions such as torticollis. They are occasionally used to relieve muscle rigidity caused by injury. Some types are used to cause temporary paralysis during surgery under general anaesthesia.Except for dantrolene, muscle-relaxant drugs partly block nerve signals that stimulate muscle contraction. Dantrolene interferes with the chemical activity in muscle cells needed for contraction.
The drugs may cause muscle weakness and drowsiness. In rare cases, dantrolene causes liver damage.
A group of drugs used to treat high blood pressure (HYPERTENSION). Untreated hypertension leads to STROKE, heart attacks and heart failure. The high incidence of hypertension in western countries has led to intensive research to discover antihypertensive drugs, and many have been marketed. The drugs may work by reducing the power of the heartbeat, by dilating the blood vessels or by increasing the excretion of salts and water in the urine (diuresis). Antihypertensive treatment has greatly improved the prognosis of patients with high blood pressure by cutting the frequency of heart and renal failure (see KIDNEYS, DISEASES OF), stroke, and coronary thrombosis (see HEART, DISEASES OF). Drugs used for treatment can be classi?ed as follows: diuretics; vasodilator antihypertensives; centrally acting antihypertensives; adrenergic neurone-blocking drugs; alpha-adrenoreceptorblocking drugs; drugs affecting the renin-angiotensin system; ganglion-blocking drugs; and tyrosine hydroxylase inhibitors. The drugs prescribed depend on many factors, including the type of hypertension being treated. Treatment can be di?cult because of the need to balance the e?ectiveness of a drug in reducing blood pressure against its side-effects.... antihypertensive drugs
Muscular tissue is divided, according to its function, into three main groups: voluntary muscle, involuntary muscle, and skeletal muscle – of which the ?rst is under control of the will, whilst the latter two discharge their functions independently. The term ‘striped muscle’ is often given to voluntary muscle, because under the microscope all the voluntary muscles show a striped appearance, whilst involuntary muscle is, in the main, unstriped or plain. Heart muscle is partially striped, while certain muscles of the throat, and two small muscles inside the ear, not controllable by willpower, are also striped.
Structure of muscle Skeletal or voluntary muscle forms the bulk of the body’s musculature and contains more than 600 such muscles. They are classi?ed according to their methods of action. A ?exor muscle closes a joint, an extensor opens it; an abductor moves a body part outwards, an adductor moves it in; a depressor lowers a body part and an elevator raises it; while a constrictor (sphincter) muscle surrounds an ori?ce, closing and opening it. Each muscle is enclosed in a sheath of ?brous tissue, known as fascia or epimysium, and, from this, partitions of ?brous tissue, known as perimysium, run into the substance of the muscle, dividing it up into small bundles. Each of these bundles consists in turn of a collection of ?bres, which form the units of the muscle. Each ?bre is about 50 micrometres in thickness and ranges in length from a few millimetres to 300 millimetres. If the ?bre is cut across and examined under a high-powered microscope, it is seen to be further divided into ?brils. Each ?bre is enclosed in an elastic sheath of its own, which allows it to lengthen and shorten, and is known as the sarcolemma. Within the sarcolemma lie numerous nuclei belonging to the muscle ?bre, which was originally developed from a simple cell. To the sarcolemma, at either end, is attached a minute bundle of connective-tissue ?bres which unites the muscle ?bre to its neighbours, or to one of the connective-tissue partitions in the muscle, and by means of these connections the ?bre affects muscle contraction. Between the muscle ?bres, and enveloped in a sheath of connective tissue, lie here and there special structures known as muscle-spindles. Each of these contains thin muscle ?bres, numerous nuclei, and the endings of sensory nerves. (See TOUCH.) The heart muscle comprises short ?bres which communicate with their neighbours via short branches and have no sarcolemma.
Plain or unstriped muscle is found in the following positions: the inner and middle coats of the STOMACH and INTESTINE; the ureters (see URETER) and URINARY BLADDER; the TRACHEA and bronchial tubes; the ducts of glands; the GALL-BLADDER; the UTERUS and FALLOPIAN TUBES; the middle coat of the blood and lymph vessels; the iris and ciliary muscle of the EYE; the dartos muscle of the SCROTUM; and in association with the various glands and hairs in the SKIN. The ?bres are very much smaller than those of striped muscle, although they vary greatly in size. Each has one or more oval nuclei and a delicate sheath of sarcolemma enveloping it. The ?bres are grouped in bundles, much as are the striped ?bres, but they adhere to one another by cement material, not by the tendon bundles found in voluntary muscle.
Development of muscle All the muscles of the developing individual arise from the central layer (mesoderm) of the EMBRYO, each ?bre taking origin from a single cell. Later on in life, muscles have the power both of increasing in size – as the result of use, for example, in athletes – and also of healing, after parts of them have been destroyed by injury. An example of the great extent to which unstriped muscle can develop to meet the demands made on it is the uterus, whose muscular wall develops so much during pregnancy that the organ increases from the weight of 30–40 g (1–1••• oz.) to a weight of around 1 kg (2 lb.), decreasing again to its former small size in the course of a month after childbirth.
Physiology of contraction A muscle is an elaborate chemico-physical system for producing heat and mechanical work. The total energy liberated by a contracting muscle can be exactly measured. From 25–30 per cent of the total energy expended is used in mechanical work. The heat of contracting muscle makes an important contribution to the maintenance of the heat of the body. (See also MYOGLOBIN.)
The energy of muscular contraction is derived from a complicated series of chemical reactions. Complex substances are broken down and built up again, supplying each other with energy for this purpose. The ?rst reaction is the breakdown of adenyl-pyrophosphate into phosphoric acid and adenylic acid (derived from nucleic acid); this supplies the immediate energy for contraction. Next phosphocreatine breaks down into creatine and phosphoric acid, giving energy for the resynthesis of adenyl-pyrophosphate. Creatine is a normal nitrogenous constituent of muscle. Then glycogen through the intermediary stage of sugar bound to phosphate breaks down into lactic acid to supply energy for the resynthesis of phosphocreatine. Finally part of the lactic acid is oxidised to supply energy for building up the rest of the lactic acid into glycogen again. If there is not enough oxygen, lactic acid accumulates and fatigue results.
All of the chemical changes are mediated by the action of several enzymes (see ENZYME).
Involuntary muscle has several peculiarities of contraction. In the heart, rhythmicality is an important feature – one beat appearing to be, in a sense, the cause of the next beat. Tonus is a character of all muscle, but particularly of unstriped muscle in some localities, as in the walls of arteries.
Fatigue occurs when a muscle is made to act for some time and is due to the accumulation of waste products, especially sarcolactic acid (see LACTIC ACID). These substances affect the end-plates of the nerve controlling the muscle, and so prevent destructive overaction of the muscle. As they are rapidly swept away by the blood, the muscle, after a rest (and particularly if the rest is accompanied by massage or by gentle contractions to quicken the circulation) recovers rapidly from the fatigue. Muscular activity over the whole body causes prolonged fatigue which is remedied by rest to allow for metabolic balance to be re-established.... muscle
ARRHYTHMIA is a variation in the normal rhythm of the heartbeat. Management of the condition requires accurate diagnosis of the type, and ELECTROCARDIOGRAPHY is vital in this process (see HEART, DISEASES OF). Drug treatment is usually part of the management, and antiarrhythmic drugs can be divided clinically into those that act on supraventricular arrhythmias, those that act on both supraventricular and ventricular arrythmias, and those that act on ventricular arrythmias. Respective examples are VERAPAMIL, DISOPYRAMIDE and LIDOCAINE. This large group of drugs can also be classi?ed according to their effects on the electrical reactions of active myocardial cells. The many drugs available are described in the British National Formulary.... antiarrhythmic drugs
A group of drugs, which include ANTIBIOTICS, used to treat infections caused by BACTERIA. Drugs include CEPHALOSPORINS and cephamycins, TETRACYCLINES, AMINOGLYCOSIDES, MACROLIDES, and antituberculous compounds.... antibacterial drugs
See NEUROLEPTICS.... antipsychotic drugs
The muscle, unique to the heart, which comprises the walls of the atria and ventricles. It consists of long broadening cells (?bres) with special physiological characteristics which enable them to keep contracting and expanding inde?nitely.... cardiac muscle
Chemicals used to kill cancerous cells. Most cytotoxic drugs also kill normal cells. There is a delicate balance between killing enough cancer cells and not so many normal cells.... cytotoxic drugs
See CONTROLLED DRUGS.... dangerous drugs
A group of chemical substances produced illegally whose properties and effects are similar to those of drugs of abuse. They may be derived from narcotic ANALGESICS, AMPHETAMINES or HALLUCINOGENS. Ecstasy is a widely used designer drug and has caused deaths among teenagers. Designer drugs are potentially dangerous, especially if taken with alcohol.... designer drugs
These widely used drugs include a range of different preparations which relieve DEPRESSION. All the antidepressants available at the time of writing are more or less equally e?ective. In studies where patients agree to take either antidepressants or identical dummy PLACEBO pills (without knowing which), at least two-thirds of those who receive antidepressants feel much better within three months, while fewer than one-third of those on placebos recover naturally in the same period. In general these drugs are useful for severe and moderate depression including postnatal illness; they are not e?ective in milder forms of depression although they may be tried for a short time if other therapies have failed.
The most widely prescribed type of antidepressants are the tricyclics, so-called because their molecular structure includes three rings. The other commonly used types are named after the actions they have on chemicals in the brain: the SELECTIVE SEROTONIN-REUPTAKE INHIBITORS (SSRIS) and the MONOAMINE OXIDASE INHIBITORS (MAOIS) – see also below. All types of antidepressant work in similar ways. Tricyclic antidepressants have cured depression in millions of people, but they can cause unpleasant side-effects, particularly in the ?rst couple of weeks. These include SEDATION, dry mouth, excessive sweating, CONSTIPATION, urinary problems, and impotence (inability to get an erection). Up to half of all people prescribed tricyclic drugs cannot tolerate the side-effects and stop treatment before their depression is properly treated. More seriously, tricyclics can upset the rhythm of the heart in susceptible people and should never be given in the presence of heart disease.
The SSRIs are newer, coming into wide use in the late 1980s. They increase the levels in the brain of the chemical messenger SEROTONIN, which is thought to be depleted in depression. Indeed, the SSRIs are as e?ective as tricyclics and, although they can cause nausea and excessive sweating at ?rst, they generally have fewer side-effects. Their main disadvantage, however, is that they cost much more than the most commonly used tricyclic, amitriptyline. On the other hand, they are more acceptable to many patients and they cause fewer drop-outs from treatment – up to a quarter rather than a half. The money saved by completed, successful treatment may outweigh the prescribing costs. SSRIs have been reported as associated with an increased risk of suicide.
Another group of antidepressants, the MAOIs, have been in use since the late 1950s.
They are stimulants, rather than sedatives, and are particularly helpful for people who are physically and mentally slowed by depression. They work well but have one big disadvantage – a dangerous interaction with certain foods and other drugs, causing a sudden and very dangerous increase in blood pressure. People taking them must carry an information card explaining the risk and listing the things that they should avoid. Because of this risk, MAOIs are not used much now, except when other treatments have failed. A new MAOI, moclobemide, which is less likely to interact and so cause high blood pressure, is now available.
LITHIUM CARBONATE is a powerful antidepressant used for intractable depression. It should be used under specialist supervision as the gap between an e?ective dose and a toxic one is narrow.
St John’s Wort is a popular herbal remedy which may be e?ective, but which is handicapped by di?erences of strength between di?erent preparations or batches. It can interact with a number of conventional drugs and so needs to be used cautiously and with advice.
In general, antidepressants work by restoring the balance of chemicals in the brain. Improved sleep and reduced anxiety are usually the ?rst signs of improvement, particularly among people taking the more sedative tricyclic drugs. Improvement in other symptoms follow, with the mood starting to lift after about two weeks of treatment. Most people feel well by three months, although a few residual symptoms, such as slowness in the mornings, may take longer to clear up. People taking antidepressants usually want to stop them as soon as they feel better; however, the risk of relapse is high for up to a year and most doctors recommend continuing the drugs for around 4–6 months after recovery, with gradual reduction of the dose after that.
Withdrawal reactions may occur including nausea, vomiting, headache, giddiness, panic or anxiety and restlessness. The drugs should be withdrawn gradually over about a month or longer (up to six months in those who have been on maintenance treatment).
A wide range of antidepressant drugs is described in the British National Formulary. Examples include:
Tricyclics: amitryptyline, imipramine, doxepin.
MAOIs: phenelzine, isocarboxazid.
SSRIs: citalopram, ?uoxetine, paraxtene. (Antidepressant drugs not in these three
groups include ?upenthixol, mertazapine and venlafaxine.)... antidepressant drugs
A group of drugs, also known as thrombolytics, with the ability to break down the protein FIBRIN, the prime constituent of blood clots (see THROMBUS; THROMBOSIS). They are used to disperse blood clots that have formed in the vessels of the circulatory system. The group includes STREPTOKINASE, alteplase and reteplase. The drugs work by activating PLASMINOGEN to form PLASMIN which degrades ?brin and breaks up the blood clot (see COAGULATION).... fibrinolytic drugs
Muscle that does not operate under a person’s conscious control. Involuntary muscle – also called smooth muscle, because the cells do not contain the striations that occur in VOLUNTARY MUSCLE – is found in blood vessels, the heart, stomach, and intestines. (See PARASYMPATHETIC NERVOUS SYSTEM.)... involuntary muscle
Muscle under a person’s voluntary control (see MUSCLE; VOLUNTARY MUSCLE).... skeletal muscle
Muscle under the ‘involuntary’ control of the autonomic nervous system (see MUSCLE; NERVOUS SYSTEM).... smooth muscle
Also known as skeletal muscle, this forms the muscles which are under a person’s conscious control. Muscles that control walking, talking and swallowing are examples of those under such control (see INVOLUNTARY MUSCLE; MUSCLE; NERVOUS SYSTEM).... voluntary muscle
Drugs used to treat hyperthyroidism, in which the thyroid gland is overactive. They may be used as the sole treatment or before thyroid surgery. Carbimazole and propylthiouracil interfere with the production of thyroid hormone by the gland.... antithyroid drugs
n. an agent that reduces tension and strain, particularly in muscles (see muscle relaxant).... relaxant
See ANALGESICS; NON-STEROIDAL ANTIINFLAMMATORY DRUGS (NSAIDS).... anti-inflammatory drugs
Any of the therapeutic substances considered indispensable for the rational care of the vast majority of diseases in a given population.... essential drugs
These drugs reduce the amount of low-density LIPOPROTEINS, which transport CHOLESTEROL and triglycerides (see TRIGLYCERIDE) in the blood, or raise the concentration of high-density lipoproteins. The aim is to reduce the progression of ATHEROSCLEROSIS and therefore help prevent coronary heart disease (see HEART, DISEASES OF). These drugs should be combined with reducing other risk factors for raised lipid concentrations, such as a high-fat diet, smoking and obesity. Lipid-regulating drugs include STATINS, ?brates, anion-exchange resins, and NICOTINIC ACID, which may be used singly or in combination under careful medical supervision (see HYPERLIPIDAEMIA).... lipid-regulating drugs
The contraction and relaxation of the limb muscles that helps pump the low pressure venous blood from the extremities back to the central collecting system.... muscle pump
All those medications requiring written notification from a doctor to a pharmacist before they can be dispensed.... prescription drugs
Drugs, such as CANNABIS and LYSERGIC ACID DIETHYLAMIDE (LSD), that expand consciousness and perception. (See DEPENDENCE.)... psychedelic drugs
In the United Kingdom, controlled drugs are those preparations referred to under the Misuse of Drugs Act 1971. The Act prohibits activities related to the manufacture, supply and possession of these drugs, and they are classi?ed into three groups which determine the penalties for o?ences involving their misuse. For example, class A includes COCAINE, DIAMORPHINE, MORPHINE, LSD (see LYSERGIC ACID DIETHYLAMIDE and PETHIDINE HYDROCHLORIDE. Class B includes AMPHETAMINES, BARBITURATES and CODEINE. Class C includes drugs related to amphetamines such as diethylpropion and chlorphentermine, meprobamate and most BENZODIAZEPINES and CANNABIS.
The Misuse of Drugs Regulations 1985 de?ne the classes of person authorised to supply and possess controlled drugs, and lay down the conditions under which these activities may be carried out. In the Regulations, drugs are divided into ?ve schedules specifying the requirements for supply, possession, prescribing and record-keeping. Schedule I contains drugs which are not used as medicines. Schedules II and III contain drugs which are subject to the prescription requirements of the Act (see below). They are distinguished in the British National Formulary (BNF) by the symbol CD and they include morphine, diamorphine (heroin), other opioid analgesics, barbiturates, amphetamines, cocaine and diethylpropion. Schedules IV and V contain drugs such as the benzodiazepines which are subject to minimal control. A full list of the drugs in each schedule can be found in the BNF.
Prescriptions for drugs in schedules II and III must be signed and dated by the prescriber, who must give his or her address. The prescription must be in the prescriber’s own handwriting and provide the name and address of the patient and the total quantity of the preparation in both words and ?gures. The pharmacist is not allowed to dispense a controlled drug unless all the information required by law is given on the prescription.
Until 1997 the Misuse of Drugs (Noti?cation and Supply of Addicts) Regulations 1973 governed the noti?cation of addicts. This was required in respect of the following commonly used drugs: cocaine, dextromoramide, diamorphine, dipipanone, hydrocodeine, hydromorphone, levorphanol, methadone, morphine, opium, oxycodone, pethidine, phenazocine and piritranide.
In 1997 the Misuse of Drugs (Supply to Addicts) Regulations 1997 revoked the 1973 requirement for noti?cation. Doctors are now expected to report (on a standard form) cases of drug misuse to their local Drug Misuse Database (DMD). Noti?cation by the doctor should be made when a patient ?rst presents with a drug problem or when he or she visits again after a gap of six months or more. All types of misuse should be reported: this includes opioids, benzodiazepines and central nervous system stimulants. The data in the DMD are anonymised, which means that doctors cannot check on possible multiple prescribing for drug addicts.
The 1997 Regulations restrict the prescribing of diamorphine (heroin), Diconal® (a morphine-based drug) or cocaine to medical practitioners holding a special licence issued by the Home Secretary.
Fuller details about the prescription of controlled drugs are in the British National Formulary, updated twice a year, and available on the Internet (see www.bnf.org).... controlled drugs
A group of drugs used to treat type-2 diabetes (see under DIABETES MELLITUS) which work by suppressing the activity of RESISTIN, a recently discovered hormone that acts against INSULIN. Resistin links obesity to type-2 diabetes which has long been known to be associated with overweight subjects.... thiazolidinedione drugs
See: SEDATIVE. ... nerve relaxant
A group of vasodilator drugs used to treat heart failure, hypertension, and diabetic nephropathy. (angiotensin converting enzyme) inhibitors are often prescribed with other drugs such as diuretic drugs or betablocker drugs. Possible side effects include nausea, loss of taste, headache, dizziness, and dry cough.... ace inhibitor drugs
A group of drugs used to treat hypertension (high blood pressure) and urinary symptoms due to enlargement of the prostate gland. Alpha-blockers are also used to treat urinary retention caused by an enlarged prostate gland (see prostate, enlarged). Side effects of the drugs may include dizziness and fatigue due to a sudden drop in blood pressure, nausea, dry mouth, and drowsiness.... alpha-blocker drugs
See also MEDICINES. Government legislation covers the manufacture, sale and prescription of drugs in the UK. As well as stating which drugs may be sold over the counter (OTC) without a doctor’s or dentist’s prescription, and those which can be obtained only with such a prescription, government regulations determine the extent of availability of many substances which are liable to be abused – see Misuse of Drugs Act 1971 (below). The Misuse of Drugs Regulations 1985 de?ne those individuals who in their professional capacity are authorised to supply and possess controlled drugs: see the schedules of drugs listed below under the 1985 regulations.
Misuse of Drugs Act 1971 This legislation forbids activities relating to the manufacture, sale and possession of particular (controlled) drugs. These are classi?ed into three grades according to their dangers if misused. Any o?ences concerning class A drugs, potentially the most damaging when abused, carry the toughest penalties, while classes B and C attract lesser penalties if abused.
Class A includes: cocaine, dextromoramide, diamorphine (heroin), lysergic acid (LSD), methadone, morphine, opium, pethidine, phencyclidine acid and injectable preparations of class B drugs.
Class B includes: oral amphetamines, barbiturates, codeine, glutethimide, marijuana (cannabis), pentazocine and pholcodine.
Class C includes: drugs related to the amphetamines, anabolic and androgenic steroids, many benzodiazepines, buprenorphine, diethyl propion, human chorionic gonadotrophin (HCG), mazindol, meprobamate, pemoline, phenbuterol, and somatropin.
Misuse of Drugs Regulations 1985 These regulations de?ne those people who are authorised in their professional capacity to supply and possess controlled drugs. They also describe the requirements for legally undertaking these activities, such as storage of the drugs and limits on their prescription.
Drugs are divided into ?ve schedules and some examples follow.
I: Almost all are prohibited except in accordance with Home O?ce authority: marijuana (cannabis), LSD.
II: High potential for abuse but have
accepted medical uses: amphetamines, cocaine.
III: Lower potential for abuse: barbiturates, meprobamate, temazepam.
IV: Lower potential for abuse than I to III. Minimal control: benzodiazepines.
V: Low potential for abuse: generally compound preparations containing small amounts of opioids: kaolin and morphine (antidiarrhoeal medicine), codeine linctus (cough suppressant).
(See also CONTROLLED DRUGS.)... misuse of drugs
These drugs produce partial or complete paralysis of skeletal muscle (see under MUSCLE – Structure of muscle). Drugs in clinical use are all reversible and are used to help insert a breathing tube into the TRACHEA (endotracheal tube) during general ANAESTHESIA and ARTIFICIAL VENTILATION OF THE LUNGS. They may be broadly divided into depolarising and nondepolarising muscle relaxants. Depolarising muscle relaxants act by binding to acetylcholine receptors at the motor end-plate where nerves are attached to muscle cells, and producing a more prolonged depolarisation than acetylcholine, which results in initial muscle fasciculation (overactivity) and then ?accid paralysis of the muscle. The only commonly used depolarising drug is succinylcholine which has a rapid onset of action and lasts approximately three minutes. Non-depolarising muscle relaxants bind to the acetylcholine receptors, preventing acetylcholine from gaining access to them. They have a slower onset time and longer duration than depolarisers, although this varies widely between di?erent drugs. They are competitive antagonists and they may be reversed by increasing the concentration of acetylcholine at the motor end-plate using an anticholinesterase agent such as neostigmine. These drugs are broken down in the liver and excreted through the kidney, and their action will be prolonged in liver and renal failure. Other uses include the relief of skeletal muscle spasms in TETANUS, PARKINSONISM and spastic disorders. The drugs dantrolene and diazepam are used in these circumstances.... muscle relaxants
These act by inhibiting the formation of PROSTAGLANDINS which are mediators of INFLAMMATION. They act both as ANALGESICS to relieve pain, and as inhibitors of in?ammation. Aspirin is a classic example of such a compound. Newer compounds have been synthesised with the aim of producing fewer and less severe side-effects. They are sometimes preferred to aspirin for the treatment of conditions such as RHEUMATOID ARTHRITIS, OSTEOARTHRITIS, sprains, strains and sports injuries. Their main side-effects are gastrointestinal: gastric ulcers and gastric haemorrhage may result (see STOMACH, DISEASES OF). This is because prostaglandins are necessary for the production of the mucous protective coat in the stomach and, when the production of prostaglandin is inhibited, the protection of the stomach is compromised. NSAIDs should therefore be used with caution in patients with DYSPEPSIA and gastric ulceration. The various nonsteroidal anti-in?ammatory drugs di?er little from each other in e?cacy, although there is considerable variation in patient response. Ibuprofen is one of the ?rst choices in this group of drugs as it combines good e?cacy with a low incidence of side-effects and administration is only required twice daily. Other drugs in this series include diclofenac, fenbufen, fenclofenac, fenoprofen, feprazone, ?urbiprofen, indomethacin, indoprofen, ketoprofen, ketorolac, naproxen, piroxicam, sulindac, tiaprofenic acid and tolmetin.... non-steroidal anti-inflammatory drugs (nsaids)
A type of antibiotic drug. Aminoglycoside drugs are given by injection and are generally reserved for the treatment of serious infections because their use can damage the inner ear or kidneys. Important examples are gentamicin and streptomycin, which are also used topically for eye and ear infections.... aminoglycoside drugs
See amfetamine drugs.... amphetamine drugs
Drugs that stimulate breathing. Replaced by ventilation, they are seldom used now.... analeptic drugs
A group of drugs that are used to eradicate worm infestations. Possible side effects include nausea, abdominal pain, rash, headache, and dizziness.... anthelmintic drugs
This group of drugs is one of three main types of drugs used to treat DEPRESSION, and was the ?rst to be introduced (in the 1950s). Tricyclic drugs work by blocking the re-uptake of the neurotransmitters SEROTONIN and NORADRENALINE (see NEUROTRANSMITTER), thus increasing the amount of the neurotransmitters at the nerve cell’s receptors. In people with depression, fewer neurotransmitters than normal are released, resulting in a slowing of neural activities. The drugs have a sedative e?ect, which can be useful for depressives with sleep problems, and an antimuscarinic action which can cause dry mouth and constipation (see ANTIMUSCARINE). Overdosage can produce COMA, ?ts (see SEIZURE) and irregular heart rhythm (ARRHYTHMIA). They are sometimes used for treating bed-wetting. (See also ANTIDEPRESSANT DRUGS.)... tricyclic antidepressant drugs
Drugs that are used to treat or prevent allergic reactions (see allergy). There are several groups, including corticosteroids, antihistamines, leukotriene receptor antagonists, and sodium cromoglicate.... antiallergy drugs
A group of drugs used to relieve the symptoms of anxiety. Benzodiazepine drugs and beta-blocker drugs are the 2 main types, although antidepressant drugs may occasionally be used. Benzodiazepine drugs promote mental and physical relaxation; they can also be used to treat insomnia, but their use for this purpose is avoided because they are addictive. Beta-blockers reduce only the physical symptoms of anxiety, such as shaking and palpitations, and are not addictive.... antianxiety drugs
Natural or synthetic androgen hormones used as drugs; one of the most important is testosterone. These drugs are used in the treatment of male hypogonadism (underactivity of the testes) to stimulate the development of sexual characteristics.
Androgen drugs are occasionally used to treat certain types of breast cancer. They have been widely used by sportsmen wishing to increase muscle bulk and strength, a practice that is dangerous to health (see steroids, anabolic).
Adverse effects include fluid retention, weight gain, increased blood cholesterol, and, rarely, liver damage. When taken by women, the drugs can cause male characteristics, such as facial hair, to develop.
androgen hormones A group of hormones that stimulate the development of male sexual characteristics.
Androgens are produced by specialized cells in the testes in males and in the adrenal glands in both sexes. The ovaries secrete very small quantities of androgens until the menopause. The most active androgen is testosterone, which is produced in the testes. The production of androgens by the testes is controlled by certain pituitary hormones, called gonadotrophins. Adrenal androgens are controlled by ACTH, another pituitary hormone.
Androgens stimulate male secondary sexual characteristics at puberty, such as the growth of facial hair and deepening of the voice. They have an anabolic effect (they raise the rate of protein synthesis and lower the rate at which it is broken down). This increases muscle bulk and accelerates growth. At the end of puberty, androgens cause the long bones to stop growing. They stimulate sebum secretion, which, if excessive, causes acne. In early adult life, androgens promote male-pattern baldness.
Androgen deficiency may occur if the testes are diseased or if the pituitary gland fails to secrete gonadotrophins. Typical effects include decreased body and facial hair, a high-pitched voice, underdevelopment of the genitalia, and poor muscle development.
Overproduction of androgens may be the result of adrenal disorders (see adrenal tumours; adrenal hyperplasia, congenital), of testicular tumours (see testis, cancer of), or, rarely, of androgensecreting ovarian tumours (see ovary, cancer of).
In men, excess androgens accentuate male characteristics; in boys, they cause premature sexual development.
In women, excess androgens cause virilization, the development of masculine features such as an increase in body hair, deepening of the voice, clitoral enlargement, and amenorrhoea.... androgen drugs
Drugs that reduce inflammation. The main groups of these drugs are nonsteroidal antiinflammatory drugs and corticosteroid drugs. (See also analgesic drugs.)... anti-inflammatory drugs
Drugs used to treat malaria. One antimalarial drug, chloroquine, is also used to treat arthritis.... antimalarial drugs
Drugs that reduce the tendency of platelets to stick together to form blood clots when blood flow in the arteries is disrupted. This action reduces the risk of thromboembolism, which can cause potentially fatal disorders such as a myocardial infarction or stroke. Aspirin and dipyridamole are commonly used antiplatelet drugs. Others, such as ticlopidine, are used specifically to protect against clots forming in the coronary arteries of people with angina.... antiplatelet drugs
Drugs that reduce fever. Examples of antipyretic drugs include paracetamol, aspirin, and other non-steroidal anti-inflammatory drugs.... antipyretic drugs
Drugs that are used to slow or halt the spread of viruses in people with HIV infection and AIDS. There are 3 main groups: reverse transcriptase inhibitors, protease inhibitors, and non-nucleoside reverse transcriptase inhibitors. Drugs from different groups are often used in combination. Antiretroviral drugs can have a range of side effects, including nausea, vomiting, diarrhoea, tiredness, and a range of effects on blood chemistry, particularly involving fats.... antiretroviral drugs
A group of drugs that relax spasm in smooth muscle in the wall of the intestine or bladder. These drugs are used to treat irritable bowel syndrome and irritable bladder. Possible side effects include dry mouth, blurred vision, and difficulty in passing urine. (See also anticholinergic drugs.)... antispasmodic drugs
Drugs that suppress or relieve a cough (see cough remedies).... antitussive drugs
See bisphosphonate drugs.... biphosphonate drugs
A group of sedative drugs that work by depressing activity within the brain. They include thiopental and phenobarbital. In the past, barbiturates were widely used as antianxiety drugs and sleeping drugs but have been largely replaced by benzodiazepine drugs and other nonbarbiturates. Barbiturates are now strictly controlled because they are habit-forming and widely abused. An overdose can be fatal, particularly in combination with alcohol, which dangerously increases the depressant effect on the brain (including suppression of the respiratory centre). However, phenobarbital is still commonly used as an anticonvulsant drug in the treatment of epilepsy. Thiopental is very short acting and is used to induce anaesthesia (see anaesthesia, general).... barbiturate drugs
A group of non-steroidal anti-inflammatory drugs (NSAIDs) that cause less stomach irritation as a side effect than other NSAIDs. Examples of -2 inhibitors include celecoxib and rofecoxib.... cox-2 inhibitor drugs
A group of drugs used to treat bleeding disorders and to control bleeding. Haemostatic preparations that help blood clotting are given to people who have deficiencies of natural clotting factors. For example, factor VIII is used to treat haemophilia. Drugs that prevent the breakdown of fibrin in clots, such as tranexamic acid, can also improve haemostasis.... haemostatic drugs
Drugs that induce sleep (see sleeping drugs).... hypnotic drugs
A group of drugs that increase the efficiency of the body’s immune system. Immunostimulant drugs include vaccines, interferon and aldesleukin (interleukin-2). Interferon is used to treat persistent viral infections, such as hepatitis C, and some types of multiple sclerosis. Aldesleukin is used in the treatment of some types of cancer.... immunostimulant drugs
Drugs used in the treatment of glaucoma to reduce pressure in the eye. Used topically, miotic drugs cause the pupil to contract, which opens up the drainage channels and drains fluid from the front of the eye. Side effects include headache, particularly over the eye, and blurred vision. Common miotics include carbachol and pilocarpine. (See also mydriatic drugs.)... miotic drugs
Drugs that make sputum (phlegm) less sticky and easier to cough up. An example is acetylcysteine.... mucolytic drugs
Sudden and involuntary contraction of a muscle. Muscle spasm is a normal reaction to pain and inflammation around a joint. Common causes are muscle strain, disc prolapse, and stress. Usually, the cause of the spasm is treated. Muscle-relaxant drugs may also be needed. (See also spasticity.)... muscle spasm
A group of drugs used to treat uveitis and to dilate the pupil during examination of the inside of the eye and for surgery. Mydriatics work by relaxing the circular muscles of the iris, causing the pupil to dilate. Common mydriatic drugs include tropicamide, cyclopentolate, homatropine, and phenylephrine. (See also cycloplegia; miotic drugs.)... mydriatic drugs
See opioid analgesic drugs.... narcotic drugs
Drugs that have been developed to treat rare conditions but are not manufactured generally.... orphan drugs
A group of drugs similar to progesterone hormone. The drugs are used in oral contraceptives, are prescribed to treat menstrual problems (see menstruation, disorders of), and are included in hormone replacement therapy (HRT). Progestogen drugs are also used to treat premenstrual syndrome, endometriosis, and hypogonadism, and are sometimes used as anticancer drugs. Adverse effects include weight gain, oedema, headache, dizziness, rash, irregular periods, breast tenderness, and ovarian cysts.... progestogen drugs
Drugs that have an effect on the mind, including hallucinogenic drugs, sedative drugs, sleeping drugs, tranquillizer drugs, and antipsychotic drugs.... psychotropic drugs
A group of drugs used to produce sedation. Sedative drugs include sleeping drugs, antianxiety drugs, antipsychotic drugs, and some antidepressant drugs. A sedative drug is often included in a premedication.... sedative drugs
A group of drugs including corticosteroid drugs and anabolic steroids (see steroids, anabolic).... steroid drugs
A group of antibacterial drugs that has largely been superseded by more effective and less toxic alternatives.... sulphonamide drugs
The natural tension in the muscle fibres. At rest, all muscle fibres are kept in a state of partial contraction by nerve impulses from the spinal cord. Abnormally high muscle tone causes an increased resistance to movement, spasticity, and rigidity. Abnormally low muscle tone causes floppiness (see hypotonia; hypotonia in infants).... tone, muscle
Drugs that have a sedative effect. Tranquillizers are divided into 2 types: major tranquillizers (see antipsychotic drugs) and minor tranquillizers (see antianxiety drugs).... tranquillizer drugs
The muscle at the back of the upper arm. At the upper end of the triceps are 3 “heads”; 1 is attached to the outer edge of the scapula (shoulderblade), and the other 2 to either side of the humerus (upper-arm bone). The lower part of the triceps is attached to the olecranon process of the ulna (the bony prominence on the elbow). Contraction of the muscle straightens the arm. (See also biceps muscle.)... triceps muscle
Drugs that are used to delay the premature delivery of a fetus. Beta2-adrenoceptor stimulants, such as salbutamol, relax the muscle of the uterus and may postpone labour for days or weeks in at-risk pregnancies of 24–33 weeks’ gestation. Delay of premature labour for up to 48 hours allows time for corticosteroid drugs to be given to the mother to help the fetal lungs to mature.... uterine muscle relaxants
see cytokine inhibitor.... anti-tnf drugs
a muscle, such as any of those controlling movements of the eyeball, that has its origin some distance from the part it acts on. See also eye.... extrinsic muscle
a muscle that is contained entirely within the organ or part it acts on. For example, there are intrinsic muscles of the tongue, whose contractions change the shape of the tongue.... intrinsic muscle
(in the UK) an Act of Parliament restricting the use of dangerous drugs. These controlled drugs are divided into three classes: class A drugs (e.g. heroin, morphine and other potent opioid analgesics, cocaine, LSD) cause the most harm when misused; class B drugs include amphetamines, barbiturates, and cannabis, and class C drugs include most benzodiazepines and anabolic steroids. The Act specifies certain requirements for writing prescriptions for these drugs. The Misuse of Drugs (Supply to Addicts) Regulations 1997 and the Misuse of Drugs Regulations 2001 lay down who may supply controlled drugs and the rules governing their supply, prescription, etc.... misuse of drugs act 1971
an agent that reduces tension in voluntary muscles. Drugs such as *baclofen, *dantrolene, and *diazepam are used to relieve skeletal muscular spasms in various spastic conditions, parkinsonism, and tetanus. The drugs used to relax voluntary muscles during the administration of anaesthetics in surgical operations act by blocking the transmission of impulses at neuromuscular junctions. Nondepolarizing muscle relaxants, e.g. *atracurium besilate, cisatracurium, pancuronium, and rocuronium, bind to receptor sites normally occupied by acetylcholine; depolarizing muscle relaxants, e.g. *suxamethonium, mimic the action of acetylcholine but *depolarization is prolonged.... muscle relaxant
a specialized receptor, sensitive to stretch, that is embedded between and parallel to the fibres of striated muscles. These receptors are important for coordinated muscular movement. See also stretch receptor.... muscle spindle
either of two muscles that cover the outer surface of the anterior wall of the pelvis (the obturator externus and obturator internus) and are responsible for lateral rotation of the thigh and movements of the hip.... obturator muscle
see Kegel exercises.... pelvic-floor muscle training
see sternomastoid muscle.... sternocleidomastoid muscle
(sternocleidomastoid muscle) a long muscle in the neck, extending from the mastoid process to the sternum and clavicle. It serves to rotate the neck and flex the head.... sternomastoid muscle
a tissue comprising the bulk of the body’s musculature. It is also known as skeletal muscle, because it is attached to the skeleton and is responsible for the movement of bones, and voluntary muscle, because it is under voluntary control. Striated muscle is composed of parallel bundles of multinucleate fibres (each containing many myofibrils), which reveal cross-banding when viewed under the microscope. This effect is caused by the alternation of actin and myosin protein filaments within each myofibril (see illustration). According to the ‘sliding filament’ theory, when muscle contraction takes place, the two sets of filaments slide past each other, so reducing the length of each unit (sarcomere) of the myofibril. The sliding is caused by a series of cyclic reactions, requiring ATP, resulting in a change in orientation of projections on the myosin filaments; each projection is first attached to an actin filament but contracts and releases it to become reattached at a different site.... striated muscle
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