Antihypertensive Drugs in Combination: Effects of Methyldopa on Thiazide-Induced Changes in Renal Hemodynamics and Plasma Renin Activity

The rise in plasma renin activity (PRA) that accompanies thiazide diuretic therapy of hypertension may interfere with therapeutic effectiveness and contribute to hypokalemia. In an attempt to provide a basis for the previously empiric use of antihypertensive drugs, 20 hypertensive subjects were given a diuretic alone for three weeks and a diuretic plus methyldopa, which lowers PRA, for three weeks. The thiazide-induced rise in PRA was blunted by the methyldopa, while blood pressure fell even more and renal function was well maintained. The combination of a renin-lowering drug and a diuretic is rational and effective therapy for hypertension.