Guide To Further Reading

Resources on the World Wide Web The 'Disease Facts' section of the website of the UK Public Health Laboratory Service (http www.phls.co.uk facts index.htm) is a valuable resource of contemporary background information on the prevalence and epidemiology of infectious diseases and antimicrobial resistance in the UK. The American FDA website gives background information on resistance with a worldwide perspective http www.fda.gov fdac features 795 antibio.html The Path of Least Resistance the...

Osmotic Laxatives

These are but little absorbed and increase the bulk and reduce viscosity of intestinal contents to promote a fluid stool. Some inorganic salts retain water in the intestinal lumen or, if given as hypertonic solution, withdraw it from the body. When constipation is mild, magnesium hydroxide will suffice but magnesium sulphate (Epsom4 salts) is used when a more powerful effect is needed. Both magnesium salts act in 2-4 h. The small amount of magnesium absorbed when the sulphate is frequently used...

Postmenopausal hormone replacement therapy HRT

HRT refers to the use of oestrogen treatment in order to reverse or prevent problems due to the loss of ovarian hormone secretion after the menopause, 5 The mares are bred on 480 farms in the prairie provinces of Canada. The 80 000 foals that are produced each year have a less medicinal future than their mothers' urine they are weaned at 120 days and sold for meat. whether physiological or induced. The tissues sensitive to oestrogen include brain, bone, skin, cardiovascular and genitourinary....

Pulmonary hypertension

Therapy is determined by the underlying cause. When the condition is secondary to hypoxia accompanying chronic obstructive pulmonary disease, long-term oxygen therapy improves symptoms and prognosis anticoagulation is essential when the cause is multiple pulmonary emboli. Primary pulmonary hypertension verapamil may give symptomatic benefit, also continuous intravenous infusion of prostaglandin. Evidence suggests that endothelin, a powerful endogenous vasoconstrictor, may play a pathogenic...

Intravenous anaesthetics

Controlled infusion (TCI) provides a convenient method for giving a continuous infusion of propofol. Central nervous system. Propofol causes dose-dependent cortical depression and is an anticonvulsant. It depresses laryngeal reflexes more than barbiturates, which is an advantage when inserting a laryngeal mask airway. Cardiovascular system. Propofol reduces vascular tone, which lowers systemic vascular resistance and central venous pressure. The heart rate remains unchanged and the result is a...

Benefits And Risks

Benefits of drugs are manifest to doctor and patient and also, it might be thought, obvious to even the most unimaginative healthy people who find themselves dismayed by some aspects of modern technology. Modern technological medicine has been criticised, justly, for following the tradition of centuries by waiting for disease to occur and then trying to cure it rather than seeking to prevent it from occurring in the first place. Although many diseases are partly or wholly preventable by...

Stimulant Laxatives

These drugs increase intestinal motility by various mechanisms they may cause abdominal cramps, should used only with caution in pregnancy, and never where intestinal obstruction is suspected. Bisacodyl stimulates sensory endings in the colon by direct action from the lumen. It is effective orally in 6-10 h and, as a suppository, acts in 1 h. In geriatric patients, bisacodyl suppositories reduce the need for regular enemas. There are no important unwanted effects. Sodium picosulphate is similar...

Criticisms Of Modern Drugs

Extremist critics have attracted public attention for their view that modern drug therapy, indeed modern medicine in general, does more harm than good others, whilst admitting some benefits from drugs, insist that this is medically marginal. These opinions rest on the undisputed fact that favourable trends in many diseases preceded the introduction of modern drugs and were due to economic and environmental changes, sanitation, nutrition and housing. They also rest on the claim that drugs have...

Notes For Prescribing Insulin

There is no need to change a stabilised diabetic from animal to human insulin. Unexplained requirement of above 100 units d is usually due to noncompliance and less often to antibodies since the withdrawal of the older insulin preparations. Allergy still occurs to additives (protamine), to the preservative, e.g. phenol, cresol, or to insulin itself. It may take the form of local reactions (inflammatory or fat atrophy) or of insulin resistance. Antibodies to insulin, provided they are moderate...

Interference With Selfregulating Systems

When self-regulating physiological systems (generally controlled by negative feedback systems, e.g. endocrine, cardiovascular) are subject to interference, their control mechanisms respond to minimise the effects of the interference and to restore the previous steady state or rhythm this is homeostasis. The previous state may be a normal function, e.g. ovulation (a rare example of a positive feedback mechanism), or an abnormal function, e.g. high blood pressure. If the body successfully...

Otheraspects Of Chronic Drug

Metabolic changes over a long period may induce disease, e.g. thiazide diuretics (diabetes mellitus), adrenocortical hormones (osteoporosis), phenytoin (osteomalacia). Drugs may also enhance their own metabolism, and that of other drugs (enzyme induction). Specific cell injury or cell functional disorder occur with individual drugs or drug classes, e.g. tardive dyskinesia (dopamine receptor blockers), retinal damage (chloroquine, phenothiazines), retroperitoneal fibrosis (methysergide), NSAIDs...

Classification Of Drugs

Drugs may be classified as producing Reduction of preload Diuretics increase salt and water loss, reduce blood volume and lower excessive venous filling pressure (see Ch. 26). The congestive features of oedema, in the lungs and periphery, are alleviated when the heart is grossly enlarged, cardiac output will also increase (see discussion of Starling curve, above). Nitrates (see also Ch. 23) dilate the smooth muscle in venous capacitance vessels, increase the volume of the venous vascular bed...

Fixeddose Drug Combinations

This section refers to combinations of drugs in a single pharmaceutical formulation. It does not refer to concomitant drug therapy, e.g. in infections, hypertension and in cancer, when several drugs are given separately. Fixed-dose drug combinations are appropriate for Convenience, with improved patient compliance. This is particularly appropriate when two drugs are used at constant dose, long term, for an asymptomatic condition, e.g. a thiazide plus a (3-adrenoceptor blocker in mild or...

Mode Of

Since the potency (therapeutic efficacy in relation to weight) of antipsychotic agents varies markedly between compounds, it is useful to think of the effective antipsychotic dose of classical agents in terms of 'chlorpromazine equivalents' (see Table 19.5). For example, haloperidol has a relatively high antipsychotic potency, such that 2-3 mg is equivalent to chlorpromazine 100 mg, whereas sulpiride 200 mg (low potency) is required for the same antipsychotic effect. Patients who are...

Moderate Efficacy Diuretics

Thiazides depress sodium reabsorption at site 3 which is just proximal to the region of sodium-potassium exchange. These drugs thus raise potassium excretion to an important extent. Thiazides lower blood pressure, initially due to reduction in intravascular volume but chronically by a reduction in peripheral vascular resistance. The latter is accompanied by diminished responsiveness of vascular smooth muscle to noradrenaline (norepinephrine) they may also have a direct action on vascular smooth...

Skin Infections

Superficial bacterial infections, e.g. impetigo, eczema, are commonly staphylococcal or streptococcal. They are treated by a topical antimicrobial for less than 2 weeks and applied twice daily after removal of crusts that prevent access of the drug, e.g. by a povidone-iodine preparation. Very extensive cases need systemic treatment. Topical fusidic acid and mupirocin are preferred (as they are not ordinarily used for systemic infections and therefore development of drug resistant strains is...

Safe Limits For Chronic Consumption

But both patients and nonpatients justifiably expect some guidance, and doctors and government departments will wish to be helpful. They may reasonably advise as a 'safe' or prudent maximum (there being no particular individual contraindication) men, not more than 21 units per week (and not more than 4 units in any one day), and women, 14 units per week (and not more than 3 units in any one day).33 Consistent drinking more than these amounts carries a...

Etn

5 Re-consider 2 causes trial of spironolactone Fig. 23.2 Scheme for escalation of anti-hypertensive therapy. A ACE inhibitor B P-adrenoceptor blocker C calcium channel blocker D diuretic (see text). (From Dickerson et al. 1999 Lancet 353 2008-2011.) small number of patients may need reversion to an older class of drug such as minoxidil (provided that a loop diuretic and (i-blocker can also be given to block the severe fluid retention and tachycardia) or methyldopa. 5. Patients whose blood...

Pregnancy Hypertension

Effective treatment of pregnancy-induced hypertension improves fetal and perinatal survival. There is a lack of good clinical trial evidence on which to base recommendations of one agent over another. Instead, drug usage reflects longevity of use without obvious harm to the fetus. Hence methyldopa is still the drug of choice for many obstetricians.35 Calcium-channel blockers (especially nifedipine) are common second-line drugs parenteral hydralazine is reserved for emergency reduction of blood...

Drugtherapy

Blood pressure may be reduced by any one or more 32 DASH-Sodium Collaborative Research Group 2001 Effects on Blood Pressure of Reduced Dietary Sodium and the Dietary Approaches to Stop Hypertension (DASH) Diet. N Engl J Med 344 3-10. of the actions listed at the beginning of this chapter (p. 46). The large number of different drug classes for hypertension reduces, paradoxically, the likelihood of a randomly selected drug being the best for an individual patient. Patients and drugs can broadly...

Treating Hypertension

A simple stepped regimen in keeping with the 1999 British Hypertension Society guidelines30 is the AB CD schema illustrated in Figure 23.2 33 1. Depending on the patient's age (see above) use either a p Blocker or thiazide Diuretic as firstline therapy, unless there is a compelling reason to avoid these (e.g. asthma and gout, respectively). If the first drug is effective but not tolerated, switch to the other member of the pair i.e. ACE inhibitor (or AIIRA) instead of P-blocker, Calcium blocker...

Drugs used in hypertension and angina

Two groups of drugs, (3-adrenergic blockers and calcium channel blockers, are used in both hypertension and angina. Several drugs for hypertension are used also in the treatment of heart failure. Diuretics, particularly the thiazides, are useful antihypertensives. They cause an initial loss of sodium with a parallel contraction of the blood and extracellular fluid volume. The effect may reach 10 of total body sodium but it is not maintained. After several months of treatment, the main blood...

Changing And Stopping Antidepressants

When an antidepressant fails through lack of efficacy despite an adequate trial or due to unacceptable side effects, it is generally advisable to change to a drug of a different class. For a patient who does not respond to an SSRI it is logical to try a TCA or a novel compound such as venlafaxine, reboxetine or mirtazapine. Any of these options may offer a greater increase in synaptic noradrenaline than the ineffective SSRI. There is also evidence to suggest that patients failing on one SSRI...

Druginduced liver damage

Sedatives, antidepressants and antiepilepsy drugs should be avoided or used with extreme caution in patients with advanced liver disease, and particularly those with current or recent hepatic encephalopathy. Enhanced sensitivity of the CNS to such drugs is well documented and adds to the pharmacokinetic changes. Treatment of alcohol withdrawal in patients with established liver disease using chlormethiazole is hazardous, especially given i.v. The temptation to give initial...

Unwanted Interactions With Antihypertensive Drugs

Specific interactions are described in the accounts of individual drugs. The following are general examples for this diverse group of drugs. Alcohol intake is the commonest contributing factor, or even cause of hypertension, and should always be considered as a cause of erratic or failed 36 The Magpie Trial Collaborative Group 2002 Lancet 359 1877-1890. 37 The Eclampsia Trial Collaborative Group 1995 Which anticonvulsant for women with eclampsia Evidence from the Collaborative Eclampsia Trial....

Dose And Usage

The total daily output of endogenous insulin from pancreatic islet cells is 30-40 units determined by the needs of completely pancreatectomised patients , and most insulin-deficient diabetics will need 30-50 unit day 0.5-0.8 units kg of insulin two-thirds in the morning and one-third in the evening . Initial treatment for a Type 1 IDDM patient, who does not present with ketoacidosis, will usually be outside hospital with two injections of intermediate-acting insulin, or a mixed insulin. Other...

Bile Salt Malabsorption

Failure of the terminal ileum to reabsorb bile salts may result from Crohn's disease, or ileal resection, and it occurs in many patients with microscopic colitis. Bile salts in the colon cause diarrhoea which is relieved by colestyramine. The dose required is titrated against symptoms, starting with 8 g bd. Colestyramine can also bind to many drugs and reduce their bioavailability see p. 131 . This condition affects 20 of the population and is the commonest reason for referral to a...

Low Efficacy Diuretics

Spironolactone Aldactone is structurally similar to aldosterone and competitively inhibits its action in the distal tubule exchange of potassium for sodium excessive secretion of aldosterone contributes to fluid retention in hepatic cirrhosis, nephrotic syndrome and congestive cardiac failure see specific use in chapter 24 , in which conditions as well as in primary hypersecretion Conn's syndrome spironolactone is most useful. Spironolactone is also useful in the treatment of resistant...

Effects of prolonged administration chronic organ toxicity

While the majority of adverse events occur within days or weeks after a drug is administered, some reactions develop only after months or years of exposure. In general, pharmacovigilance programmes reveal such effects once recognised, they demand careful monitoring during chronic drug therapy for their occurrence may carry serious consequences for the patient and the nonvigilant doctor, medico-legally . Descriptions of such types C and D reactions appear with the accounts of relevant drugs some...

Vehicles For Presenting Drugs To The Skin

The formulations are described in order of decreasing water content. All water-based formulations must contain preservatives, e.g. chlorocresol, but these rarely cause allergic contact dermatitis. Water is the most important component. Wet dressings are generally used to cleanse, cool and relieve pruritus in acutely inflamed lesions, especially where there is much exudation, e.g. atopic eczema. The frequent reapplication and the cooling effect of evaporation of the water reduce the inflammatory...

Advantages And Disadvantages Of Parenteral Administration

An i.v. bolus, i.e. rapid injection, passes round the circulation being progressively diluted each time it is delivered principally to the organs with high blood flow brain, liver, heart, lung, kidneys . Advantages are that the i.v. route gives swift, effective and highly predictable blood concentration and allows rapid modification of dose, i.e. immediate cessation of administration is possible if unwanted effects occur during administration. The route is suitable for administration of drugs...

Granuloma Inguinale

Calymmatobacterium granulomatis infection is treated with ampicillin or co-trimoxazole or a tetracycline for 2 weeks. BACTERIAL VAGINOSIS BACTERIAL VAGINITIS.ANAEROBIC VAGINOSIS Bacterial vaginosis is a common form of vaginal discharge in which neither Trichomonas vaginalis nor Candida albicans can be isolated and inflammatory cells are not present. There is evidence to associate the condition with overgrowth of several normal commensals of the vagina including Gardnerella vaginalis,...

Advantages And Disadvantages Of Enteral Administration

For systemic effect Advantages are convenience and acceptability. Disadvantages are that absorption may be delayed, reduced or even enhanced after food or slow or irregular after drugs that inhibit gut motility antimuscarinic, opioid . Differences in presystemic elimination are a cause of variation in drug effect between patients. Some drugs are not absorbed gentamicin and some drugs are destroyed in the gut insulin, oxytocin, some penicillins . Tablets taken with too small a quantity of liquid...

Mucolytics And Expectorants

Normally about 100 ml of fluid is produced from the respiratory tract each day and most of it is swallowed. Respiratory mucus consists largely of water and its slimy character is due to glycoproteins cross-linked together by disulphide bonds. In pathological states much more mucus may be produced an exudate of plasma proteins which bond with glycoproteins and form larger polymers results in the mucus becoming more viscous. Patients with chest diseases such as cystic fibrosis and bronchiectasis...

Morphine On Smooth Muscle

Morphine activates receptors on the smooth muscle of the stomach antrum and of both large and small bowel, causing it to contract. Peristalsis propulsion is reduced and segmentation increased. Thus, although morphine 'stimulates' smooth muscle, delayed gastric emptying and constipation occur, with gut muscle in a state of tonic contraction. Delay in the passage of the intestinal contents results in greater absorption of water and increased viscosity of faeces, which contribute...

Drugspecific Rashes

Despite great variability, some hints at drug-specific Drugs applied locally or taken systemically often bardie R A, Savin J A1979 British Medical Journal 1935, to cause rashes. These take many different forms and whom we are grateful for this quotation and classification. or characteristic rashes from drugs taken systemically, can be discerned, as follows Acne and pustular e.g. corticosteroids, androgens, Ciclosporin, penicillins. Allergic vasculitis e.g. sulphonamides, NSAIDs, thiazides,...

Amfetamines

Amfetamine has had multifarious uses. It is now obsolete for depression and as an appetite suppressant, and its use in sport is abuse see before . There is concern that its illicit use as a psychostimulant is widespread. Amfetamine is a racemic compound the laevo-form is relatively inactive but dexamphet-amine the dextro- isomer finds use in medicine. Amfetamine will be described, and structurally-related drugs only in the ways in which they differ. Mode of action. Amfetamine acts by releasing...

Organic Nitrates

Organic nitrates and nitrite were introduced into medicine in the 19th century.1 Denitration in the smooth muscle cell releases nitric oxide NO , which is the main physiological vasodilator, normally produced by endothelial cells. Nitrodilators a generic term for drugs that release or mimic the action of NO activate the soluble guanylate cyclase in vascular smooth muscle cells and cause an increase in intracellular cyclic GMP guanosine monophosphate con 1 Murrell, W 1879 Nitroglycerin as a...

Adrenergic Neuron Blocking Drugs

Adrenergic neuron blocking drugs are selectively taken up into adrenergic nerve endings by the active, energy-requiring, saturable amine noradrenaline pump mechanism uptake-1 . They accumulate in the noradrenaline storage vesicles from which they are released in response to nerve impulses, diminishing the release of noradrenaline and so all sympathetic function. They do not adequately control supine blood pressure and are prone to interactions with other drugs affecting adrenergic function,...