Trial of atenolol and chlorthalidone for hypertension in black South Africans.

Twenty-four black patients (Zulus) with hypertension participated in a double-blind, placebo-controlled cross-over trial of the efficacy of a beta-blocking agent (atenolol) 100 mg once daily as compared with chlorthalidone 25 mg once daily. The two drugs were also given combined at these doses and the effects compared with those of the drugs given alone. Atenolol as sole treatment had no appreciable effect on blood pressure as compared with placebo. Chlorthalidone produced a small decrease, but this was not statistically significant. Combining the two drugs, however, produced a significant reduction in blood pressure (mean lying blood pressure p < 0.001; mean standing blood pressure p < 0.0002). These findings suggest that beta-blockers should not be regarded as baseline treatment of hypertension in blacks.