Prazosin GITS vs atenolol in patients with hypertension and normal lipid profile: a randomized, controlled multicenter study. Hyderabad Hypertension Study Group.

Objective: To compare the long-term antihypertensive efficacy, tolerability, and metabolic effects of prazosin GITS and atenolol.

Design: Randomized, controlled, multicenter study of 26 weeks duration.

Setting: Office practices of 24 physicians in Hyderabad, Andhra Pradesh, 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 a normal 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 atenolol (Tenormin 50-100 mg once 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 serum lipids at the end of weeks 8, 16, and 24 of treatment; mean change in laboratory parameters for safety at the end of week 24; frequency and intensity of adverse events judged probably or definitely related to the drug.

Results: 62 patients randomized to prazosin GITS group and 60 to atenolol group. Of these, 39 in prazosin GITS group (M 23, F 16; mean age-48.4 yr, SEM 1.60) and 39 in atenolol group (M 24, F 15; mean age-42.9 yr, SEM 1.48) completed the entire study. Percent patients with DBP < 90 mm Hg at 24 weeks: prazosin GITS--92.3%, atenolol--92.3%; SBP < 140 mm Hg: prazosin GITS--89.7% atenolol--94.9% both DBP < 90 mm Hg and SBP < 140 mm Hg: prazosin GITS--87.2%, atenolol--89.7%; percent patients with DBP fall of 10 mm Hg or more at 24 weeks: prazosin GITS--92.3%, atenolol--100%. 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, except at week 2, when the fall was greater for atenolol (8.8 mm Hg vs 11.4 mm Hg, p = 0.05). Treatment with prazosin GITS resulted in a favourable effect on the serum lipid profile at the end of 24 weeks (p = 0.02 for total cholesterol, p = 0.015 for the ratio of total to HDL cholesterol, p = 0.04 for LDL cholesterol). Atenolol, on the other hand, did not produce any significant change in the metabolic parameters at the end of 24 weeks. Adverse events probably or definitely related to the drug: prazosin GITS--in 10.3% patients, atenolol--in 16.7% patients.

Conclusion: In the doses used, both prazosin GITS and atenolol had comparable efficacy and tolerability. While atenolol was neutral on serum lipids, prazosin GITS showed a beneficial effect at the end of 24 weeks.