The antihypertensive effect of pinacidil versus prazosin in mild to moderate hypertensive patients seen in general practice.

The antihypertensive effect of a new vasodilating drug, pinacidil, was compared with prazosin in a randomized, open study in general practice including 131 patients with a sitting diastolic blood pressure (DBP) between 100-115 mmHg. At inclusion 108 patients were untreated and the remaining patients were on treatment with thiazide diuretics and/or beta-blockers. The aim was to reduce the sitting DBP to less than or equal to 95 mmHg, which was achieved in 85% of the patients treated with pinacidil and in 77% of the patients treated with prazosin (NS). In the responding patients the reductions were (mean +/- SD) 16 +/- 7 mmHg (p less than 0.001) and 13 +/- 6 mmHg (p less than 0.001) in the pinacidil group (n = 60) and the prazosin group (n = 46), respectively (p less than 0.10). During 5 months of maintenance therapy no statistically significant differences in blood pressures between the two treatment groups were present. Side-effects were typical of vasodilator therapy, i.e. headache, dizziness, tachycardia and edema, leading to discontinuation of therapy in 10 patients in each treatment group. Heart rate (HR) was increased with pinacidil and unchanged with prazosin. Edema was frequently seen with pinacidil and dizziness with prazosin. Because of edema a thiazide diuretic was given to nine patients in the pinacidil group and two patients in the prazosin group. No clinically significant changes in ECG and biochemical variables were observed. In conclusion, the study has demonstrated that pinacidil is as effective an antihypertensive agent as prazosin. Pinacidil may be used as monotherapy. However, the study suggests that pinacidil should be used as add-on therapy to thiazide diuretics.