Diuretic treatment in essential hypertension.

In North America, diuretics remain the most common first-line drug therapy for essential hypertension based on efficacy, safety and cost. The promotion of step-care programmes has firmly established their dominant use on this continent whereas in Europe, particularly in Scandinavia and Great Britain, beta-adrenoceptor blocking agents are more frequently chosen as first-line therapy. On both continents, combined therapy with a diuretic and a beta-blocker is probably the most common second step for patients with blood pressures uncontrolled on a single agent alone and diuretics remain useful, if not essential, to prevent sodium retention commonly observed with other antihypertensive agents. Although the forced loss of sodium and water may be responsible for their initial antihypertensive effect, the mechanism underlying their long-term effect is unknown but probably involves some alteration of vascular smooth muscle reactivity. More recently, concern has been expressed about their long-term safety as larger populations are being exposed to diuretic agents for a significant proportion of their life-span. These concerns include haemodynamic and biochemical consequences of diuretic therapy - excessive tachycardia at rest and with minimal exercise, postural hypotension, hypokalaemia and arrhythmias, muscle cramps or fatigue, glucose intolerance, hyperuricaemia and altered circulating lipids as markers or promotors of atherosclerosis and its complications. At present, there is insufficient evidence to alter the present recommendation of diuretic agents as first-line drug therapy in the treatment of hypertension.