ADVERSE REACTION SURVEILLANCE
Almost all drugs have adverse effects associated with their use; these range in severity from mild inconven-iences to severe morbidity and death. Some adverse ef- fects are extensions of the drug’s pharmacological effect and are predictable, for example, orthostatic hypoten-sion with some antihypertensive agents, arrhythmias with certain cardioactive drugs, and electrolyte imbal-ance with diuretics. Other adverse effects are not pre-dictable and may occur rarely or be delayed for months or years before the association is recognized. Examples of such reactions are aplastic anemia associated with chloramphenicol and clear cell carcinoma of the uterus in offspring of women treated with diethylstilbestrol during pregnancy. Postmarketing surveillance programs and adverse reaction reporting systems may detect such events. The best defense against devastating adverse ac-tions is still the vigilance and suspicion of the physician.