Renal excretory actions of antihypertensive agents: Effects of rilmenidine

The acute renal excretory actions of several antihypertensive agents were assessed in healthy volunteers. Rilmenidine (1 mg) did not affect water and electrolyte balance. Beta-adrenergic blockers had little effect upon urinary composition, whereas diuretics caused significant urinary losses of fluid, sodium, potassium, and magnesium as expected. The vasodilators ketanserin and flosequinan did not affect water and electrolyte excretion. Ketanserin increased urate output in common with angiotensin-converting enzyme inhibitors, which may act as facultative diuretics. Combining the angiotensin-converting enzyme inhibitor captopril (100 mg) or rilmenidine (1 mg) with hydrochlorothiazide (25 mg) had little influence upon the known actions of the diuretic. When the beta-blocker pindolol (10 mg) was given with the diuretic clopamide (5 mg), beneficial effects were noted; potassium and magnesium losses were markedly reduced, whereas the natriuretic and diuretic effects of clopamide were unchanged. These short-term studies in healthy volunteers provide useful pointers to some possible pharmacodynamic effects of antihypertensive drugs in patients.