Antihypertensive effect of low-dose hydrochlorothiazide alone or in combination with quniapril in black patients with mild to moderate hypertension

In this study, using 24-hour ambulatory blood pressure (BP) monitoring, the authors assessed the potential for BP control using hydrochlorothiazide (H CTZ, 12.5 mg daily), given as a monotherapy over 12 months to 49 black Sout h African patients with mild to moderate hypertension (mean day diastolic b lood pressure [DBP] greater than or equal to 90 and < 115 mmHg). Uncontroll ed patients received fixed combination of quinapril/HCTZ 10/12.5, 20/12.5, and 20/25 mg, with dose titration at 3 monthly intervals if BP control was nor achieved (day DBP < 90 mmHg). Overall, profound and sustained BP reduct ion was observed at the end of the study. The 24-hour BP decreased from 151 +/- 14/98 +/- 7 to 136 +/- 15/87 +/- 9mmHg (p < 0.0001 at end of study vs. baseline); the mean day BP decreased from 155 +/- 14/104 +/- 7 to 140 +/- 15/91 +/- 10 mmHg (p < 0.0001 at end of study vs. baseline). The overall co ntrol (mean day DBP < 90 mmHg) and response (decrease day DBP greater than or equal to 10 mmHg) rates were 49% and 61%, respectively. At the end of th e study only 2 patients (4%)remained on treatment with HCTZ. Out of the ini tial 12 patients controlled on HCTZ at 3 months (12/49, 24%), 5 patients re mained controlled at 6 months and only 1 patient at 12 months. In contrast, quinapril/HCTZ combinations maintained their antihypertensive effect up to 9 months, with a significant number of patients (22/49, 45%) requiring the highest dose of the combination (20/25 mg daily). In conclusion, low-dose HCTZ should not be recommended as monotherapy in black patients with mild t o moderate hypertension due to the fact that the BP-lowering effect is atte nuated already at 6 months of treatment, with most patients requiring the a ddition of the ACE inhibitor. (C) 2000 the American College of Clinical Pha rmacology.