Comparison of labetalol and clonidine in hypertension

The antihypertensive effect of labetalol (L) was compared with that of clonidine (C) in a randomized cross-over study in 17 hypertensive outpatients on bendrofluazide (B). After treatment for two weeks with B (5 mg qd), either L (100 mg tid) or C (0.1 mg tid) was given and their doses were titrated at 2-weekly visits until normotension was achieved, or intolerable side-effects occurred. The treatment with B and L or C was then continued in a cross-over fashion for two 6-week periods, with 3 week diuretic washouts and subsequent dose-titration periods between the treatment periods. At the end of B, the supine blood pressure (BP) was 156/101, and at the end of B + L and B + C it was 136/91 (p<0.001) and 137/91 (p<0.001), respectively, pooling the data from both periods. At the end of B, the standing BP was 155/115, and at the end of B + L and B + C 134/100 (p<0.001) and 139/106 (p<0.001), respectively. The mean daily doses required were L 476mg and C 0.335 mg. On a weight basis, labetalol had about 1/1400 of the potency of clonidine. 12 patients complained of tiredness and dry mouth on clonidine and 2 patients of unsteadiness on labetalol. Labetalol caused a psoriasiform rash on the hands in one patient and limb weakness in one patient.