Abstract
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 160mg initially and 320mg subsequently versus chlorthalidone 50mg daily. Thereafter, a combination of oxprenolol with chlorthalidone in an initial dose of 160mg and 25mg and a subsequent dose of 320mg and 50mg, 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<0.01). Combining the 2 drugs enhanced their blood pressure lowering effects (p<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 pro-duce a further increase in its blood pressure lowering effect.
