Effects of combined enalapril and folic acid therapy on the serum uric acid levels in hypertensive patients: a multicenter, randomized, double-blind, parallel-controlled clinical trial

Abstract

Objective The efficacy of combined treatment consisting of enalapril and folic acid (FA) was compared to that of enalapril alone in reducing the serum uric acid (UA) levels in adult hypertensive patients in China. Methods Patients with mild to moderate hypertension (n=480) were randomly assigned to one of three treatment groups: (1) 10 mg enalapril (control group), (2) 10 mg enalapril plus 0.4 mg FA (low-FA group) or (3) 10 mg enalapril plus 0.8 mg FA (high-FA group) daily for eight weeks. The primary outcome was the UA ratio (week 8 UA: baseline UA). Results The final analysis included 450 patients (43.1% men, 27-75 years of age). An adjusted multivariable regression analysis revealed no significant differences in the UA ratio between the three groups after eight weeks of treatment. In the subgroup analysis stratified according to the baseline UA level, the high-FA group demonstrated a significantly greater UA-lowering response among the patients with an elevated baseline UA concentration (UA ≥310 μmol/L) [median UA ratio (25th percentile, 75th percentile): 0.94 (0.83, 1.01)], compared with that observed in the control group [0.97 (0.90, 1.00), p=0.025]. Similar results were found in the participants with baseline hyperuricemia (HUA; UA: men >420 μmol/L, women >350 μmol/L). Conclusion In this sample of adult hypertensive patients, the administration of a daily dose of 10 mg of enalapril combined with 0.8 mg of FA had a greater beneficial effect on the serum UA levels than did that of 10 mg of enalapril alone in patients with either an elevated UA concentration or HUA.