Combined action of enalapril or timolol with hydrochlorothiazide plus amiloride in hypertension.

59 mild to moderate hypertensives were treated for four weeks with 50 mg hydrochlorothiazide plus 5 mg of amiloride, then concomitantly with these diuretics with either enalapril (10-20 mg) or timolol (10-20 mg) in two parallel treatment groups for an additional 12 weeks in an open study. Addition of these drugs lowered the blood pressure by 25 +/- 3/16 +/- 2 mm Hg and 15 +/- 3/14 +/- 1 mm Hg, respectively. The difference of the reduction of the systolic blood pressure between enalapril and timolol group at the end of the combined treatment was statistically significant (p less than 0.01). The mean serum potassium was elevated by 0.3 mmol/l after addition of enalapril to the diuretic treatment, but none of the patients developed hyperkalaemia. No adverse effects on other routine laboratory values were observed. Both drug combinations can be considered efficient, well tolerated and safe in the treatment of mild to moderate hypertension.