DIFFERENTIAL-EFFECTS OF ENALAPRIL AND ATENOLOL ON PROTEINURIA AND RENAL HEMODYNAMICS IN NONDIABETIC 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 (> 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 > 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 < 95 mm Hg or of > 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 < 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 < 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.