A comparison of four primary classes of antihypertensive monotherapy in Thai patients

Efficacy of four primary classes of antihypertensive agents (diuretics, angiotensin converting enzyme inhibitors, calcium antagonists, adrenergic inhibiting drugs) were compared by using a crossectional medical record survey between July 1997 and January 1998. Only hypertensive cases with initial monotherapy were studied. The evaluations were 1) blood pressure response after drug titration and 2) blood pressure response during the maintenance phase. Two hundred and eighty nine patients were studied. After dose titration, the mean reduction in systolic blood pressure with calcium antagonists (33 +/- 24 mmHg, mean +/- SD) was better than other drugs (p < 0.05) while there was no difference in the other three drug classes in systolic blood pressure reduction. The mean reduction in diastolic blood pressure with calcium antagonists (17 +/- 9 mmHg) was better than angiotensin converting enzyme inhibitors (13 +/- 9, p = 0.02) but without significant difference compared to the other two drug classes. There was no difference in diastolic blood pressure reduction from diuretics, angiotensin converting enzyme inhibitors and adrenergic inhibiting drugs. In the maintenance phase, the response rate for calcium antagonists (82.6%) was better than angiotensin converting enzyme inhibitors (54.2%, p = 0.004) but was not better than the other two drug classes. Response rates for diuretics, angiotensin converting enzyme inhibitors and adrenergic inhibiting drugs were not statistically different.