ObjectiveSeveral experimental and clinical studies indicate that the renin system may play a pivotal role in progressing renal disease. The combination of an angiotensin-converting enzyme inhibitor and an angiotensin receptor blocker could provide a higher degree of blockade of the renin-angiotensin system than either agent alone. Such enhanced suppression might be of benefit for patients exhibiting a progressive decline in renal function because of chronic renal disease.MethodsA pilot multinational, multicentre, randomized, active-controlled, parallel group open-label study has been conducted in a group of patients with progressive chronic renal failure (creatinine clearance 20–45 ml/min) either with or without proteinuria and hypertension. The primary aim of the study was to investigate the safety and tolerability of the combination of valsartan and benazepril. Patients were randomly assigned to one of three groups: group 1 received valsartan 160 mg once daily (n = 22); group 2 received valsartan 80 mg once daily plus benazepril 5 or 10 mg once daily (n = 42); group 3 received valsartan 160 mg once daily plus benazepril 5 or 10 mg once daily (n = 44). The study lasted for 5 weeks, and in groups 2 and 3 benazepril was added on top of valsartan after the first week of therapy with the angiotensin receptor blocker.ResultsSerum creatinine increased in all three groups (mean change within a group: 11 μmol/l in group 1,P= 0.045; 9 μmol/l in group 2,P= 0.030; 15 μmol/l in group 3,P= 0.0006). Serum potassium also increased in all three groups of patients (mean change within a group:0.28 mmol/l in group 1,P= 0.28; 0.48 mmol/l in group 2,P= 0.0008; 0.36 mmol/l in group 3,P= 0.02). After 5 weeks of treatment, the largest decrease in blood pressure was observed in group 3 (the mean change from baseline in seated diastolic blood pressure (SDBP) and seated systolic blood pressure (SSBP), respectively, were: −2.0 and −11.5 mmHg in group 1; −7.6 and −15.4 mmHg in group 2; −12.6 and −21.6 mmHg in group 3). In addition, both combination treatments resulted in the reduction of proteinuria. The total number of patients with adverse experiences were 10 (45.5%), 14 (33.3%) and 11 (25%) in groups 1, 2 and 3, respectively. In six patients (5.6%) therapy was discontinued as a result of adverse experiences. Only one patient in each of the combined therapy groups withdrew from the study because of hyperkalaemia and no patients were forced to withdraw because of an increase in serum creatinine, acute renal failure or hospitalization.ConclusionsThese results indicate that short-term combination of an angiotensin-converting enzyme inhibitor and an angiotensin receptor blocker is safe and well tolerated in patients with moderate chronic renal failure.