Effects of placebo versus guanabenz on hypertensive out-patients

The objectives of this study were two-fold: (1) 1 4-week multicentre, randomized, double-blind efficacy comparison of placebo and guanabenz acetate, a new centrally acting antihypertensive drug, in 168 hypertensive out-patients and (2) a more accurate determination of the incidence of drug-related, non-specific side-effects. Both treatment groups were comparable: 68% female, 63% black, mean age 53 years; 57% mild, 32% moderate, 11% moderately severe hypertensives. Seventy-six placebo patients completed 4 weeks and had a mean supine diastolic blood pressure (SDBP) decrease from 105 to 101 mm Hg (p < 0.01). Seventy-nine guanabenz patients completing 4 weeks had a mean SDBP decrease from 104 to 92 mm Hg (p < 0.01). All of the placebo responses and 10/12 mm Hg of the guanabenz response occurred during Week 1. Clinically significant individual SDBP decreases occurred in thirty-one (41%) placebo and fifty-five (70%) guanabenz-treated patients (p < 0.01). Mean daily guanabenz dose was 24 mg. Drug-related biochemical or electrocardiographic abnormalities were absent. Side-effects of sedation and dry mouth were recorded two and three times more frequently, respectively, in guanabenz as compared to placebo patients. Side-effects usually occurred within Week 1 and diminished in incidence thereafter. Consequently, in these patients it appeared that: (1) guanabenz was an effective, well-tolerated drug, (2) placebo effects on efficacy were significant, occurred early and remained stable, and (3) placebo and guanabenz side-effects were mainly sedation and dry mouth.