A group of drugs used to treat high blood pressure (HYPERTENSION). Untreated hypertension leads to STROKE, heart attacks and heart failure. The high incidence of hypertension in western countries has led to intensive research to discover antihypertensive drugs, and many have been marketed. The drugs may work by reducing the power of the heartbeat, by dilating the blood vessels or by increasing the excretion of salts and water in the urine (diuresis). Antihypertensive treatment has greatly improved the prognosis of patients with high blood pressure by cutting the frequency of heart and renal failure (see KIDNEYS, DISEASES OF), stroke, and coronary thrombosis (see HEART, DISEASES OF). Drugs used for treatment can be classi?ed as follows: diuretics; vasodilator antihypertensives; centrally acting antihypertensives; adrenergic neurone-blocking drugs; alpha-adrenoreceptorblocking drugs; drugs affecting the renin-angiotensin system; ganglion-blocking drugs; and tyrosine hydroxylase inhibitors. The drugs prescribed depend on many factors, including the type of hypertension being treated. Treatment can be di?cult because of the need to balance the e?ectiveness of a drug in reducing blood pressure against its side-effects.... antihypertensive drugs