Dual renin-angiotensin system blockade at optimal doses for proteinuria

Background. The antiproteinuric effect of combining the angiotensin-converting enzyme (ACE) inhibitor lisinopril and the angiotensin II (Ang II) antagonist losartan was compared to that of the optimal antiproteinuric doses of monotherapy. Methods. To this purpose, lisinopril and losartan were studied in 9 nondiabetic renal patients with median proteinuria 4.5 g/day (95% Cl, 3.5, 6.4), creatinine clearance of 80 mL/ min (95% CI, 66, 96), and mean arterial pressure (MAP) of 102 mm Hg (95 % CI, 93, 112). First, in two protocols with six-week treatment periods per dose, the optimal antiproteinuric dose of each drug was established in each patient. Losartan and lisinopril were used in randomized order, each preceded by a baseline period without medication. The doses of losartan (mg/day) were 50, 100, 150, and again 50. The lisinopril doses were 10, 20, 40, and again 10. After the second protocol, patients were treated with a combination, using the optimal antiproteinuric doses established for the individual drugs. Results. The antiproteinuric response by losartan was optimal at 100 mg (-46%; 95% CI, -60, -24%), being larger than at the 50 mg dose (-27%; 95% CI, -42, -4%, P < 0.05), but not different from the 150 mg dose (-46%; 95% CI, -58; -20%). Proteinuria decreased further at each up-titration step of lisinopril to - 75 % (95 % CI, - 85, -43 %) at the 40 mg dose. Combination therapy reduced proteinuria more effectively (-85%; 95% Cl, -96, -58) than monotherapy with losartan, and to a lesser extent than with lisinopril. Optimal blood pressure responses were obtained at similar doses. Conclusions. Dose-titration with a renin-angiotensin system blocker, followed by add-on therapy is highly effective in order to reduce proteinuria. The safety of this regimen needs to be addressed in future studies.