Differing dosages of captopril and hydrochlorothiazide in the treatment of hypertension: long-term effects metabolic values and intracellular electrolytes.

The effects of long-term treatment with differing dosages of captopril and hydrochlorothiazide in combination were evaluated in 22 hypertensive patients. There was no significant difference in antihypertensive efficacy between captopril 25 mg twice a day in combination with hydrochlorothiazide 25 mg once or twice daily and captopril 50 mg twice a day in the same combination. About 75% of patients achieved normotension. Once daily therapy with captopril 50 mg and hydrochlorothiazide 25 mg was effective in only 25% of patients. Long-term treatment (11 months) with captopril and hydrochlorothiazide did not cause any of the metabolic effects usually observed during diuretic administration. Intracellular (lymphocytic) Na+ was significantly reduced and intracellular K+ significantly increased by captopril and hydrochlorothiazide, and this led to the normalization of the intracellular Na+:K+ ratio, which is abnormally high in essential hypertension. Our data suggest that the association of low doses of captopril and hydrochlorothiazide is highly effective, well tolerated, prevents the metabolic side effects of diuretics, and has favorable effects on intracellular ionic composition.