Efficacy and tolerability of long term oxprenolol and chlorthalidone singly and in combination in hypertensive blacks
Sixty two black patients who had confirmed but untreated hypertension participated in a double blind clinical trial of the efficacy and tolerability of slow-release oxprenolol in a daily dose of 160 mg initially and 320 mg subsequently versus chlorthalidone 50 mg daily. Thereafter, a combination of oxprenolol with chlorthalidone in an initial dose of 160 mg and 25 mg and a subsequent dose of 320 mg and 50 mg, respectively, was administered and the effects compared with those of the same drugs given singly. The trial lasted for 3 years, but each participant took active medication for 1 year. Oxprenolol as monotherapy had no effect on the blood pressure, irrespective of the dose. Chlorthalidone as monotherapy produced a significant fall in blood pressure (p less than 0.01). Combining the 2 drugs enhanced their blood pressure lowering effects (p less than 0.001). Oxprenolol as monotherapy and as part of combination therapy was well tolerated by all patients. Chlorthalidone as monotherapy was well tolerated by most patients while a fraction of the patients developed biochemical derangements. These results confirm the findings that a beta-blocker alone may be ineffective in lowering blood pressure in hypertensive blacks. The results also show that the efficacy and tolerability of a beta-blocker and a diuretic are enhanced by their combined administration. Finally, the results show that increasing the dose of a beta-blocker or a diuretic does not produce a further increase in its blood pressure lowering effect.