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Recent European Union draft guidelines for the safety evaluation of drugs intended for long-term use state that during drug development the safety profile of the new compound should be assessed over a period of time consistent with intended usage. This is in reasonable agreement with guidelines prepared by other regulatory authorities.Satisfactory preclinical data on a new compound are used to obtain authorization for human testing from the National Committees on Safety of Medicines. Clinical trials are performed in four phases, ranging from phase I studies performed on healthy volunteers (n=20-50) to postmarketing (phase IV) studies. The latter are of great importance as they cover large patient populations (n=2000 to >10 000) and allow detection of rare adverse drug reactions.Type B reactions are serious, unpredictable reactions to a drug that necessitate treatment withdrawal. Type A reactions are dose-dependent, and represent the majority of adverse reactions. They are often managed by dose reduction rather than drug withdrawal.Examples of type B adverse reactions to antihypertensives are the cutaneous and ocular reactions to practolol, and angioneurotic oedema associated with angiotensin converting enzyme inhibitors. Lacidipine, a second-generation calcium antagonist, is an example of a modern antihypertensive agent with a favourable safety profile. The adverse reactions associated with lacidipine are mild to moderate and of the A type, the major ones being those typical of calcium antagonists (headache, flushing and pedal oedema due to vasodilation).