Antihypertensive effect of single doses of enalapril in hypertensive patients treated with bendrofluazide.

This study was designed to investigate the validity of the then current recommendations for initiation of therapy with enalapril in hypertensive patients on treatment with a diuretic. Enalapril in single doses of 10 and 20 mg was given to 13 hypertensive patients on treatment with bendrofluazide 5 mg daily in a randomised, crossover, placebo controlled study. The mean maximal reduction in blood pressure was similar with both doses (35/20 mmHg supine, 38/20 mmHg standing), occurred on average within 6 h of tablet ingestion, and was not accompanied by any significant change in heart rate. Three patients experienced symptomatic hypotension. In one patient this was incapacitating after 10 mg and precluded exposure to 20 mg. This study shows that in hypertensive patients receiving treatment with diuretics, the addition of enalapril should be undertaken with caution. An optimal starting dose of enalapril in such patients remains to be confirmed.