Objective: The influence of angiotensin II AT-1 receptor antagonists on uric acid metabolism, and the potential differences among them with regard to this effect, remains to be precisely established. This study was designed to compare the effects of losartan and eprosartan on uric acid metabolism in patients with mild to moderate essential hypertension.
Design: Randomized, double-blind, parallel-group study in hypertensive patients.
Setting: Outpatient clinic.
Patients: Following a 2- to 3-week single-blind placebo run-in period, 60 patients with sitting diastolic blood pressure > or = 95 and < or = 114 mmHg were randomized. Fifty-eight patients completed the study.
Interventions: Patients were randomized to receive losartan 50 mg or eprosartan 600 mg once daily for 4 weeks.
Main outcome measures: The primary endpoint was the change in the ratio of urinary uric acid/creatinine in the period 0-4 h of a 24 h urine collection after 4 weeks of treatment. Secondary endpoints included 24 h urinary uric acid excretion, as well as serum urate and anti-hypertensive efficacy.
Results: Mean urinary uric acid/creatinine changes from baseline were 0.14 (day 1) and 0.11 (week 4) for losartan and -0.04 for eprosartan (at both day 1 and week 4; P < 0.01 between groups at both time-points). The mean increase in 24 h urinary uric acid excretion with losartan was 0.7 mmol/24 h (25% increase from baseline) at both day 1 and week 4. No significant difference was observed in the change of serum urate levels versus baseline between both treatment groups after 4 weeks (- 23.4 and - 19.5 micromol/l for losartan and eprosartan, respectively). Patients with hyperuricaemia in both treatment groups showed similar modifications of uric acid metabolism compared with non-hyperuricaemic subjects. Blood pressure control (sitting diastolic blood pressure < 90 mmHg or < 100 mmHg with a decrease of at least 10 mmHg from baseline) was achieved in 22 patients (73%) with eprosartan and in 16 (53%) with losartan.
Conclusions: Losartan increased uric acid excretion in hypertensive patients, whilst eprosartan did not Neither AT-1 receptor antagonist substantially modified serum urate concentrations.