Additive antiproteinuric effect of combined ACE inhibition and angiotensin II receptor blockade.

BACKGROUND: Limitation of systemic and glomerular hypertension reduces urinary protein excretion and prevents renal function deterioration.

OBJECTIVE: To investigate whether, in hypertensive patients with glomerulonephritis, a combination of an angiotensin converting enzyme inhibitor (ACEI, fosinopril 20 mg/day) with an angiotensin receptor blocker (ARB, irbesartan 150 mg/day) produces a more profound antiproteinuric effect than either drug alone.

METHODS: Ten non-diabetic patients with glomerulonephritis, normal or slightly reduced but stable renal function (creatinine clearance 40-106 ml/min) without immunosuppression were studied. Clinical evaluations, 24 h blood pressure measurements and laboratory tests were performed as follows: (1) without medication (baseline) and in random sequence; (2) ACEI alone; (3) ARB alone; and (4) combination of ACEI + ARB. Each period lasted for 6 weeks, separated by three washout periods of 4 weeks each without therapy.

RESULTS: ACEI and ARB alone reduced proteinuria from 7.9 +/- 7.1 to 5.3 +/- 5.2 and 5.0 +/- 4.9 g/24 h (mean +/- SD), respectively. The combination of ACEI + ARB induced a more remarkable reduction of proteinuria in every patient (to 3.3 +/- 3.7 g/24 h) than either drug alone (P = 0.039 by ANOVA). The enhanced antiproteinuric effect of the combined therapy could not be attributed to a more pronounced reduction of 24 h mean arterial pressure (basal, 106 +/- 8; ACEI, 97 +/- 5; ARB, 98 +/- 5; ACEI+ARB, 95 +/- 5 mmHg) or creatinine clearance (basal, 77 +/- 27; ACEI, 73 +/- 31; ARB 80 +/- 30; ACEI + ARB, 73 +/- 32 ml/min).

CONCLUSIONS: A combination of ACEI and ARB in patients with glomerulonephritis produces a more profound decrease in proteinuria than either drug alone. This additive antiproteinuric effect is not dependent on changes in blood pressure or creatinine clearance. A long-term controlled study is required to confirm the positive effect of this treatment on the progression of renal function loss.