Uricosuric effect of losartan in patients with renal transplants

Background. The aim of the study was to evaluate the uricosuric effect of the angiotensin II receptor antagonist, losartan, in hypertensive patients with renal transplants who are treated with cyclosporin A (CsA). Methods. Twenty-six patients with stable renal function and hypertension, 16 men and 10 women, median age 47 years (range, 25-63 years), were studied in an open randomized crossover trial, comparing a 2-week control period with a 2-week period of once-daily administration of 50 mg of losartan. The main outcome measurements were fractional excretion of uric acid (FEuric acid) based on 24-hr urine collections and plasma uric acid. Results. The median FEuric acid was 5.7% (range, 2.4-10.4%) in the control period with a median change of +0.84% (range, -1.15% to +2.77%) in the losartan period (P <0.0002). Plasma uric acid was 0.47 mM (0.29-0.69 mM) in the control period with a change of -0.03 mM (-0.10 to 0.06 mM) in the losartan period (P <0.002). Diastolic blood pressure was 87 mmHg (70-97 mmHg) in the control period with a change of -3 mmHg (-13 to +6 mmHg) in the losartan period (P <0.005). There was no difference in systolic blood pressure between the two study periods. Plasma creatinine was 165 muM (102-356 muM) in the control period with a change of +9 mul (-36 to +60 muM) in the losartan period (P <0.01). Plasma potassium was 4.2 mM (3.0-4.7 mM) in the control period with a change of + 0.2 mM (-0.2 to +0.9 mM) in the losartan period (P <0.0005). Conclusions. Once-daily administration of 50 mg of losartan in hypertensive CsA-treated patients with renal transplants caused a 17% increase in FEuric acid and an 8% fall in plasma uric acid.