n. one thousandth of a gram. Symbol: mg.
A tin-like metal, cadmium accumulates in the body. Long-term exposure can lead to EMPHYSEMA, renal failure (see KIDNEYS, DISEASES OF) and urinary-tract CALCULI. Acute exposure causes GASTROENTERITIS and PNEUMONITIS. Cadmium contamination of food is the most likely source of poisoning. The EU Directive on the Quality of Water for Human Consumption lays down 5 milligrams per litre as the upper safe level.... cadmium poisoning
A high blood-cholesterol level – that is, one over 6 mmol per litre or 238 mg per 100 ml – is undesirable as there appears to be a correlation between a high blood cholesterol and ATHEROMA, the form of arterial degenerative disease associated with coronary thrombosis and high blood pressure. This is well exempli?ed in DIABETES MELLITUS and HYPOTHYROIDISM, two diseases in which there is a high blood cholesterol, sometimes going as high as 20 mmol per litre; patients with these diseases are known to be particularly prone to arterial disease. There is also a familial disease known as hypercholesterolaemia, in which members of affected families have a blood cholesterol of around 18 mmol per litre or more, and are particularly liable to premature degenerative disease of the arteries. Many experts believe that there is no ‘safe level’ and that everybody should attempt to keep their cholesterol level as low as possible.
Cholesterol exists in three forms in the blood: high-density lipoproteins (HDLs) which are believed to protect against arterial disease, and a low-density version (LDLs) and very low-density type (VLDLs), these latter two being risk factors.
The rising incidence of arterial disease in western countries in recent years has drawn attention to this relationship between high levels of cholesterol in the blood and arterial disease. The available evidence indicates that there is a relationship between blood-cholesterol levels and the amount of fat consumed; however, the blood-cholesterol level bears little relationship to the amount of cholesterol consumed, most of the cholesterol in the body being produced by the body itself.
On the other hand, diets high in saturated fatty acids – chie?y animal fats such as red meat, butter and dripping – tend to raise the blood-cholesterol level; while foods high in unsaturated fatty acids – chie?y vegetable products such as olive and sun?ower oils, and oily ?sh such as mackerel and herring – tend to lower it. There is a tendency in western society to eat too much animal fat, and current health recommendations are for everyone to decrease saturated-fat intake, increase unsaturated-fat intake, increase daily exercise, and avoid obesity. This advice is particulary important for people with high blood-cholesterol levels, with diabetes mellitus, or with a history of coronary thrombosis (see HEART, DISEASES OF). As well as a low-cholesterol diet, people with high cholesterol values or arterial disease may be given cholesterol-reducing drugs such as STATINS, but this treatment requires full clinical assessment and ongoing medical monitoring. Recent research involving the world’s largest trial into the effects of treatment to lower concentrations of cholesterol in the blood showed that routine use of drugs such as statins reduced the incidence of heart attacks and strokes by one-third, even in people with normal levels of cholesterol. The research also showed that statins bene?ted women and the over-70s.... cholesterol
5: VITAMINS.)... pantothenic acid
Normally, a young child requires a smaller dose than an adult. There are, however, other factors than age to be taken into consideration. Thus, children are more susceptible than adults to some drugs such as MORPHINE, whilst they are less sensitive to others such as ATROPINE. The only correct way to calculate a child’s dose is by reference to texts supplying a recommended dose in milligrams per kilogram. However, many reference texts simply quote doses for certain age-ranges.
Old people, too, often show an increased susceptibility to drugs. This is probably due to a variety of factors, such as decreased weight; diminished activity of the tissues and therefore diminished rate at which a drug is utilised; and diminished activity of the KIDNEYS resulting in decreased rate of excretion of the drug.
Weight and sex have both to be taken into consideration. Women require slightly smaller doses than men, probably because they tend to be lighter in weight. The e?ect of weight on dosage is partly dependent on the fact that much of the extra weight of a heavy individual is made up of fatty tissue which is not as active as other tissues of the body. In practice, the question of weight seldom makes much di?erence unless the individual is grossly over- or underweight.
Idiosyncrasy occasionally causes drugs administered in the ordinary dose to produce unexpected effects. Thus, some people are but little affected by some drugs, whilst in others, certain drugs – for example, psychoactive preparations such as sedatives – produce excessive symptoms in normal or even small doses. In some cases this may be due to hypersensitivity, or an allergic reaction, to the drug, which is a possibility that must always be borne in mind
(e.g. with PENICILLIN). An individual who is known to be allergic to a certain medication is strongly advised to carry a card to this e?ect, and always to inform medical and dental practitioners and/or a pharmacist before accepting a new prescription or buying an over-the-counter preparation.
Habitual use of a drug is perhaps the in?uence that causes the greatest increase in the dose necessary to produce the requisite e?ect. The classical example of this is with OPIUM and its derivatives.
Disease may modify the dose of medicines. This can occur in several ways. Thus, in serious illnesses the patient may be more susceptible to drugs, such as narcotics, that depress tissue activity, and therefore smaller doses must be given. Again, absorption of the drug from the gut may be slowed up by disease of the gut, or its e?ect may be enhanced if there is disease of the kidneys, interfering with the excretion of the drug.
Fasting aids the rapidity of absorption of drugs, and also makes the body more susceptible to their action. Partly for this reason, as well as to avoid irritation of the stomach, it is usual to prescribe drugs to be taken after meals, and diluted with water.
Combination of drugs is to be avoided if possible as it is often di?cult to assess what their combined e?ect may be. In some cases they may have a mutually antagonistic e?ect, which means that the patient will not obtain full bene?t. Sometimes a combination may have a deleterious e?ect.
Form, route and frequency of administration Drugs are now produced in many forms, though tablets are the most common and, usually, convenient. In Britain, medicines are given by mouth whenever possible, unless there is some degree of urgency, or because the drug is either destroyed in, or is not absorbed from, the gut. In these circumstances, it is given intravenously, intra-muscularly or subcutaneously. In some cases, as in cases of ASTHMA or BRONCHITIS, the drug may be given in the form of an inhalant (see INHALANTS), in order to get the maximum concentration at the point where it is wanted: that is, in the lungs. If a local e?ect is wanted, as in cases of diseases of the skin, the drug is applied topically to the skin. In some countries there is a tendency to give medicines in the form of a suppository which is inserted in the rectum.
Recent years have seen developments whereby the assimilation of drugs into the body can be more carefully controlled. These include, for example, what are known as transdermals, in which drugs are built into a plaster that is stuck on the skin, and the drug is then absorbed into the body at a controlled rate. This method is now being used for the administration of GLYCERYL TRINITRATE in the treatment of ANGINA PECTORIS, and of hyoscine hydrobromide in the treatment of MOTION (TRAVEL) SICKNESS. Another is a new class of implantable devices. These are tiny polymers infused with a drug and implanted just under the skin by injection. They can be tailored so as to deliver drugs at virtually any rate – from minutes to years. A modi?cation of these polymers now being investigated is the incorporation of magnetic particles which allow an extra burst of the incorporated drug to be released in response to an oscillating magnetic ?eld which is induced by a magnetic ‘watch’ worn by the patient. In this way the patient can switch on an extra dose of drug when this is needed: insulin, for instance, in the case of diabetics. In yet another new development, a core of drug is enclosed in a semi-permeable membrane and is released in the stomach at a given rate. (See also LIPOSOMES.)... dosage
Uses The main use of iron is in the treatment of iron-de?ciency anaemias (See ANAEMIA.) Iron preparations sometimes cause irritation of the gastrointestinal tract, and should therefore always be taken after meals. They sometimes produce a tendency towards constipation. Whenever possible, iron preparations should be given by mouth; if PARENTERAL administration is clinically necessary because of malabsorption, a suitable preparation is iron sorbitol injection given intramuscularly. Most patients respond successfully to oral iron preparations.... iron
TUBERCULIN PURIFIED PROTEIN DERIVATIVE (TUBERCULIN PPD) is the active principle of OT (see above), and is prepared from the ?uid medium on which the Mycobacterium tuberculosis has been grown. It is supplied as a liquid, a powder, or as sterile tablets. The liquid contains 100,000 units per millilitre, and the dry powder contains 30,000 units per milligram. It is distributed in sterile containers sealed so as to exclude micro-organisms. It is more constant in composition and potency than OT.
Uses The basis of the tuberculin reaction is that any person who has been infected with the Mycobacterium tuberculosis gives a reaction when a small amount of tuberculin is injected into the skin. A negative reaction means either that the individual has never been infected with the tubercle bacillus, or that the infection has been too recent to have allowed of sensitivity developing.
There are various methods of carrying out the test, of which the following are the most commonly used. The Mantoux test is the most satisfactory of all, and has the advantage that the size of the reaction is a guide to the severity of the tuberculous infection: it is performed by injecting the tuberculin into the skin on the forearm. The Heaf multiple puncture test is reliable: it is carried out with the multiple puncture apparatus, or Heaf gun. The Vollmer patch test, using an impregnated ?lter paper, is useful in children because of the ease with which it can be carried out.... varieties
Deficiency. Sun sensitivity; exposure inducing itching, burning and swelling of the skin. Kidney, bladder, and gut infections. Severe earache in young children. Strokes, heart attacks.
It is claimed that those who eat a diet rich in beta-carotene are less likely to develop certain types of cancer.
Smokers usually have low levels of beta-carotene in the blood. Statistics suggest that people who eat a lot of beta-carotene foods are less likely to develop lung, mouth or stomach cancer. In existing cases a slow-down of the disease is possible.
Daily dose. Up to 300mg. Excess may manifest as yellow discoloration of the skin, giving appearance of sun-tan.
Sources. Mature ripe carrots of good colour. A Finland study suggests that four small carrots contain sufficient beta-carotene to satisfy the recommended daily amount of Vitamin A. Orange and dark green fruits and vegetables. Broccoli, Brussels sprouts, spinach, pumpkin, apricots, peaches, oranges, tomatoes. Harvard Medical School study. Among 333 subjects with a history of heart disease, those who received beta-carotene supplements of 50 milligrams every other day suffered half as many heart attacks as those taking placebos. (Dr Charles Hennekens, Harvard Medical School) ... beta-carotene
In Greenland, where much oily fish is eaten, heart disease is scarcely known. Each year over 200,000 people in Britain alone die of heart disease. Western affluence-diseases from a diet of excess saturated fat (from meat, butter, etc) may be reduced by modest amounts of oily fish.
A daily intake of 800 milligrams of essential fatty acids as contained in herring, mackerel, cod, etc., can play a decisive role in cardiac treatments. Such fish may be eaten twice weekly. On days when not taken, supplement with pure fish oil or fish oil capsules. As little as 1oz (30 grams) of mackerel, herring or other similar fish is sufficient.
When eating oily fish only twice a week a teaspoon of pure fish oil or dessertspoon cod liver oil daily is sufficient.
Labels of fish oils should be carefully studied for their DHA and EPA content in milligrams. Add together to a total 800 milligrams – average daily dose.
Fish oils can lower the level of triglycerides and reduce ‘stickiness’ of the blood – its tendency to clot and possibly block coronary vessels. As fish oil Vitamin A contains 10,000iu of Retinol, it should not be taken for extended periods without the advice of a practitioner. ... fish oils
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