Chlorthalidone in mild hypertension - dose response relationship.

The dose response curve for 25, 50, 75 and 100 mg doses of chlorthalidone was studied in double blind fashion over an 8 week period in patients who presented with untreated mild hypertension. One hundred and thirty four patients completed this multicentre, family practice study. After 2 week's medication, a decline in blood pressure was noted in all dosage groups and this was maximal by 4 weeks. At 8 weeks all doses of chlorthalidone induced a significant reduction in both systolic and diastolic blood pressure (mean -18 and -10 mmHg respectively). Amongst the 4 dosage groups, no differences in response were noted resulting in a flat dose response curve. During the study, mean blood urea and serum uric acid rose whilst serum potassium fell, the urea and potassium being least affected in the 25 mg dosage group. As the dosage of chlorthalidone increased, so the tendency for abnormal laboratory values increased. Unwanted effects sought during the study were relatively few in number. No clear dose response relationship was evident although the positive responses in the 25 mg dosage group were less than in the higher dosages. These results suggest that 25 mg chlorthalidone is the optimum dosage for initiation of therapy in patients with mild to moderate hypertension. This dosage is associated with less adverse biochemical changes and unwanted effects than the higher dosage studied.

RCT Entities:   Population Interventions Outcomes