Differential effects of enalapril and atenolol on proteinuria and renal haemodynamics in non-diabetic renal disease.

OBJECTIVE: To compare the antihypertensive, renal haemodynamic and antiproteinuric effect of enalapril and atenolol in patients with proteinuria of non-diabetic origin. DESIGN: Prospective, double blind, randomised 16 week study after a pretreatment period of at least three weeks. SETTING: Outpatient nephrology and hypertension unit. PATIENTS: 27 patients with proteinuria (greater than 300 mg protein/day) of non-diabetic origin, moderately impaired renal function (creatinine clearance 30-90 ml/min), and a pretreatment diastolic blood pressure of greater than 80 mm Hg. INTERVENTIONS: Treatment with enalapril (10 mg/day, adjusted between 5 and 40 mg, if necessary) or atenolol (50 mg/day, adjusted between 25 and 100 mg if necessary) titrated against a target fall in diastolic blood pressure to less than 95 mm Hg or of greater than 10 mm Hg, or both. MAIN OUTCOME MEASURES: Blood pressure, renal haemodynamics, and urinary protein excretion. RESULTS: No differences were detected between the two groups before treatment. The falls in systolic and diastolic blood pressures during treatment were not significantly different between both groups. Proteinuria fell slightly with atenolol but significantly more with enalapril (mean change -0.38 (95% confidence interval -0.78 to 0.03) v -1.2 (-1.70 to -0.69) g/day respectively, p less than 0.02) as did filtration fraction (mean change -1.8 (-2.9 to -0.7) v -3.8 (-4.9 to -2.8)% respectively. Serum potassium concentration increased with enalapril (mean change 0.63 (SD 0.51) v 0.19 (0.47) mmol/l, p less than 0.05). CONCLUSIONS: Enalapril lowers proteinuria more than atenolol in patients with non-diabetic renal disease despite a similar blood pressure lowering effect of both drugs, and its antiproteinuric effect seems to be associated with the characteristic renal haemodynamic effect of angiotensin converting enzyme inhibitors.