Comparison of indapamide and hydrochlorothiazide plus amiloride as a third drug in the treatment of arterial hypertension.

In a randomized, double-blind crossover trial, indapamide (IND) 2.5 mg and hydrochlorothiazide 25 mg + amiloride 2.5 mg (HCTZ + A) were found to be equally effective in reducing blood pressure (BP) in 13 patients with moderate to severe hypertension already receiving chronic treatment with a beta blocker and a vasodilatator (supine BP during run-in: 169/103 +/- 21/5 mmHg; on IND: 149/91 +/- 21/14 mmHg; on HCTZ + A 144/88 +/- 23/5 mmHg). Both drugs induced insignificant reductions in body weight, and no change in plasma volume was seen. Serum potassium was significantly reduced on both regimens--the values recorded on IND being significantly lower than those seen on HCTZ + A. Values below 3.0 mmol/l were found in two patients receiving IND, but no subjective side effects were reported. Hyperuricemia occurred with the same frequency on both regimens. It is concluded that IND, just like the thiazide diuretics, is useful as the third drug in patients needing triple drug therapy to control BP, but metabolic adverse effects are not avoided by the choice of this drug.