Additive antiproteinuric effect of converting enzyme inhibitor and losartan in normotensive patients with IgA nephropathy

We tested the hypothesis that the combination of converting enzyme inhibito r (CEI) with losartan (LOS) produces a more profound antiproteinuric effect than either drug alone in normotensive patients with immunoglobulin A (IgA ) nephropathy, Eight normotensive (mean blood pressure, 88.9 +/- 2.1 mm Hg) patients with biopsy-proven IgA nephropathy, nonnephrotic proteinuria (pro tein, 1 to 3 g/d), and normal or slightly reduced creatinine clearance (ran ge, 69 to 119 mL/min) were studied. Clinical evaluations and laboratory tes ts were performed (1) before CEI treatment (basal) and after (2) CEI alone (CEI, 12 weeks); (3) the combination of CEI and LOS, the latter at a dosage of 50 mg/d (CEI + LOS, 4 weeks); (4) LOS alone (LOS; 50 mg/d; 12 weeks); ( 5) the combination of LOS and CEI(LOS + CEI, 4 weeks, at the same dosage as CEI + LOS); and (6) a doubled dose of either CEI alone or LOS alone for 4 weeks. CEI and LOS as monotherapy significantly reduced proteinuria by 38% and 30%, respectively. No further reduction of proteinuria was achieved by doubling the dose of CEI or LOS, Both combinations induced a more remarkabl e reduction of proteinuria (73%; P < 0.05 v other periods) than either drug administered alone. The antiproteinuric effect of CEI or LOS and the more remarkable effect achieved with both combinations was not dependent on the reduction of blood pressure and/or creatinine clearance. In conclusion, thi s study provides first-time evidence that the combination of CEI and LOS in normotensive patients with IgA nephropathy produces a more profound decrea se in proteinuria than either drug. This additive antiproteinuric effect is not dependent on changes in systemic blood pressure and creatinine clearan ce. Nevertheless, a larger controlled study is required to confirm this nov el observation, (C) 1999 by the National Kidney Foundation, Inc.