Once vs twice daily administration of a fixed combination of captopril plus hydrochlorothiazide in essential hypertension: a double-blind crossover study in known responders to a standard combination.

The purpose of this randomized, double-blind, crossover trial was to compare the hypotensive effects of a fixed combination of captopril (C) 50 mg and hydrochlorothiazide (HCTZ) 25 mg (C 50/HCTZ 25) once daily with those of a fixed combination of C 25 mg and HCTZ 12.5 mg (C 25/HCTZ 12.5) twice daily. We studied 199 patients (108 M, 91 F) with mild to moderate essential hypertension whose BP was already controlled by the co-administration of C 25 mg and HCTZ 12.5 mg twice daily. They were randomly assigned to either C 25/HCTZ 12.5 twice daily during the first 6 weeks and C 50/HCTZ 25 once daily during the second 6 weeks or C 50/HCTZ 25 once daily followed by C 25/HCTZ 12.5 twice daily. Both regimens showed comparable efficacy on office diastolic BP (91.6 vs 91.3 mm Hg). Systolic BP was slightly but significantly higher (P = 0.02) with the once daily formulation (141.2 vs 139.1 mm Hg). Fixed combinations once daily and twice daily resulted in identical working ambulatory BP (133.7 +/- 13/83.6 +/- 8 mm Hg vs 132.4 +/- 11/83.3 +/- 7 mm Hg) without affecting heart rate. Adverse events were reported by 16% of patients and cough was the most common occurring in 7%. In conclusion, these results indicate that the fixed combination of C 50/HCTZ 25 given once daily controls office and working BP as well as the fixed combination C 25/HCTZ 12.5 given twice daily in patients with mild to moderate hypertension.