Comparison of slow-release piretanide and bendroflumethiazide in the treatment of mild to moderate hypertension.

After 4 weeks of placebo treatment, 76 hypertensive patients were randomly allocated to 6 or 12 mg/day piretanide, or 2.5 mg/day bendroflumethiazide for 12 weeks in a double-blind study. Piretanide was given in a slow-release formulation and bendroflumethiazide as a tablet. All three treatments produced a significant reduction in supine and erect systolic and diastolic blood pressures after 2 weeks, and this effect was maintained throughout the study. Normotension (i.e. supine diastolic pressure less than or equal to 95 mmHg) was achieved in 73% of the patients receiving 12 mg/day piretanide and in 57% receiving 6 mg/day piretanide compared with 72% receiving bendroflumethiazide (not significant). Overall, five patients were withdrawn due to increased diuresis: two patients on each dosage of piretanide and one receiving bendroflumethiazide. Three patients receiving 6 mg/day piretanide were withdrawn due to diastolic blood pressure rising above 120 mmHg. Other side-effects reported were mild and transient. There were no significant changes in serum creatinine, glucose or high-density lipoprotein cholesterol. A small, but non-significant rise in uric acid level was seen in all three groups. Clinically relevant hypokalaemia requiring potassium supplementation occurred in three patients receiving bendroflumethiazide.