Effects of dihydropyridine calcium antagonists on albuminuria in patients with diabetes

The present study was designed to assess the effects of two different dyhydropyridine calcium antagonists (DHPCAs) on proteinuria in patients with noninsulin-dependent diabetes mellitus (NIDDM). The hypothesis that similar levels of blood pressure reduction with two different DHPCAs produce similar degrees of proteinuria reduction was tested. In a prospective randomized study, 14 patients with NIDDM, hypertension, proteinuria, and renal insufficiency were given either isradipine (n = 7) or nifedipine XL (n = 7) for 6 months. After a 2-week washout period, patients were crossed over to the other drug and observed for an additional 6 months. Drugs were titrated to lower arterial pressure to <140/90 mmHg. Patients also instructed to follow a low-sodium diet at the initial visit. Blood pressure and 24-hour urine values for creatinine clearance, albuminuria, proteinuria, and sodium were assessed monthly. At the end of the initial and crossover treatment periods, there were no significant reductions in the level of albuminuria from baseline with either drug. Sodium excretion was <110 mEq/L with each drug tested. The results of this study support the concept that DHPCAs do not reduce proteinuria in patients with type II diabetes. This failure to reduce albuminuria and proteinuria occurred despite adequate blood pressure reduction and an effort at dietary sodium restriction.