Therapeutic aims should be clear. Combinations should not be prescribed unless there is good reason to consider that the patient needs all the drugs in the formulation and that the doses are appropriate and will not need to be adjusted separately. Rational combinations can provide advantage, just as inappropriate combinations may be dangerous. Thus a combination of iron with folic acid and cyanocobalamin would be hazardous if it delays the diagnosis of pernicious anaemia. But the fact that iron plus a little folic acid is properly used in pregnancy for routine anaemia prophylaxis simply confirms that combinations can be rationally devised to meet particular needs.
With many drugs there are differences in pharmacodynamics and pharmacokinetics according to whether their use is in a single dose or over a brief period (acute pharmacology) or long term (chronic pharmacology). The proportion of the population taking drugs continuously for large portions of their lives increases as tolerable suppressive and prophylactic remedies for chronic or recurrent conditions are developed; e.g. for arterial hypertension, diabetes mellitus, mental diseases, epilepsies, gout, collagen diseases, thrombosis, allergies and various infections. In some cases long-term treatment introduces significant hazard into patients' lives and the cure can be worse than the disease if it is not skilfully managed. In general the dangers of a drug are not markedly increased if therapy lasts years rather than months; exceptions include renal damage due to analgesic mixtures, and carcinogenicity.
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Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...