Abstract
OBJECTIVE:
To compare the long-term antihypertensive efficacy, tolerability, and metabolic effects of prazosin GITS and a sustained release (SR) preparation of nifedipine.
DESIGN:
Randomized, controlled, multicenter study of 26 weeks duration.
SETTING:
Office practices of 24 physicians in Chennai, Tamil Nadu, India.
PATIENTS:
Males and females, aged 30 to 70 yrs, with hypertension of JNC V stage 1 or 2 at the end of a 2-week placebo run-in period, and an abnormal lipid profile. Sufficient number of patients recruited so that at least 60 complete the entire study.
INTERVENTIONS:
Prazosin GITS (Minipress XL, 2.5-5 mg once daily) or sustained release nifedipine (Nicardia Retard 10-20 mg twice daily) for upto 6 weeks, continued upto 24 weeks in those showing a pre-defined response (SBP and/or DBP normalized, or DBP fall of at least 10 mm Hg with actual value of DBP < 95 mm Hg). Patients allocated to either of the two interventions by randomization.
OUTCOME MEASURES:
Percent patients showing pre-defined BP response at week 6; percent patients with DBP < 90 mm Hg, SBP < 140 mm Hg, and both; percent patients with DBP fall > or = 10 mm Hg; mean fall in BP among those receiving treatment for 24 weeks; mean change in blood glucose and serum lipids at the end of weeks 8, 16, and 24 of treatment; frequency and intensity of adverse events judged probably or definitely related to the drug.
RESULTS:
54 patients randomized to prazosin GITS group and 52 to nifedipine SR group. Of these, 39 in prazosin GITS group (M 23, F 16; mean age-50. 6 yr, SEM 1.66) and 36 in nifedipine SR group (M 20, F 16; mean age-52.3 yr, SEM 1.71) completed the study. Percent patients with DBP < 90 mm Hg at 24 weeks: prazosin GITS--100%, nifedipine SR--100%; SBP < 140 mm Hg: prazosin GITS--94.9%, nifedipine SR--91.7%; both DBP < 90 mm Hg and SBP < 140 mm Hg: prazosin GITS--92.3%, nifedipine SR--91.7%; percent patients with DBP fall of 10 mm Hg or more at 24 weeks: prazosin GITS--76.9%, nifedipine SR--83.3%. The mean fall in the systolic and diastolic blood pressure from the end-of-placebo-phase values to all the other time points was comparable in the 2 groups. Treatment with prazosin GITS did not produce any statistically or clinically significant change in the metabolic parameters at the end of 24 weeks, while with nifedipine SR there was a significant increase in the serum LDL values at 24 weeks (p = 0.009). Adverse events probably or definitely related to the drug: prazosin GITS--1.9%, nifedipine SR--2.1%.
CONCLUSION:
Both drugs were equally effective and well tolerated. While prazosin GITS was neutral on serum lipids, use of nifedipine SR was associated with a significant increase in serum LDL cholesterol at the end of 24 weeks.