Labetalol compared with prindolol plus hydraliazine in the treatment of hypertension: a double-blind cross-over study.

The hypotensive action of labetalol, a new drug with alpha-adrenoceptor and beta-adrenoceptor blocking action, was compared with that of a combination of prindolol and hydrallazine. Fourteen patients with mild to moderately severe hypertension completed a double-blind cross-over study with treatment periods of eight weeks. Both treatments were effective and, in the doses which were used, produced clinically significant lowering of blood pressure (reduction of mean blood pressure by more than 10 mm Hg) both in clinic and in home blood pressures in 12 of the 14 patients. The action of labetalol (600 mg twice a day) was approximately equivalent to that of prindolol (15 mg twice a day) plus hydrallazine (50 mg three times a day). There was a tendency for the second treatment (irrespective of nature) to be more effective than the first. However, when the results for each treatment were combined, the fall in the blood pressure due to labetalol was practically identical with that due to prindolol and hydrallazine. There were no toxic effects from either treatment and side effects were mild. Labetalol is a useful hypotensive drug with effect similar to that of a combination of a beta-adrenoceptor blocking drug and a vasodilator.