Double-blind comparator trials with pinacidil, a potassium channel opener

The antihypertensive effects of pinacidil, a potassium channel opener, were studied in 4, dose titration, double-blind trials. Patients had mild to severe hypertension, with supine diastolic arterial pressures between 91 and 150mm Hg during the qualification assessment. Efficacy was assessed using an 'intention-to-treat' analysis. In one study, pinacidil-treated patients had a response rate significantly greater than placebo-treated patients. In another study, the pinacidil group had a response rate significantly greater than the prazosin group (83% vs 75%, respectively). In a third study, the response rate in the pinacidil group was marginally greater than in the hydralazine group (77% vs 73%, respectively). In a 'step 2' trial, pinacidil was as effective as methyldopa and more effective than placebo. Adverse experiences with pinacidil were associated with vasodilatation. Electrocardiographic T wave changes occurred intermittently and may be related to its mechanism of action. These studies suggest that antihypertensive monotherapy with pinacidil was effective and generally well tolerated.