Low-dose captopril: its use in mild to moderate hypertension unresponsive to diuretic treatment.

The effect of low doses (25 mg three times a day) of captopril was evaluated in 16 patients with mild to moderate essential hypertension, previously uncontrolled by hydrochlorothiazide. After a no-treatment period, mean eight-hour seated diastolic blood pressure (SDBP, mm Hg) was 103 +/- 5 on placebo, 95 +/- 8 after a single dose of captopril, 96 +/- 4 after two weeks of captopril alone, and 90 +/- 6 after its combination with hydrochlorothiazide. Though nine patients had at least a 10% fall in SDBP after the initial dose of captopril, only three had a comparable fall after two weeks; after captopril and hydrochlorothiazide, however, 12 patients had such a response. Captopril decreased mean angiotensin-converting enzyme activity and plasma aldosterone, though to a lesser extent with continued therapy. Because its side effects appear dose related, low doses of captopril combined with a diuretic are effective and may be better tolerated.