Effects of Calcium Channel Blockers on Proteinuria in Patients With Diabetic Nephropathy

Diabetic nephropathy management should include the use of an angiotensin‐converting enzyme inhibitor (ACEI) or an angiotensin receptor blocker with additional antihypertensive medications to reduce proteinuria and cardiovascular events. Some studies suggest that adding a nondihydropyridine rather than a dihydropyridine calcium channel blocker (CCB) may more effectively lower proteinuria. We hypothesized that a trandolapril/verapamil SR (T/V) fixed‐dose combination (FDC) was superior to a benazepril/amlodipine (B/A) FDC for reducing albuminuria in 304 hypertensive diabetic nephropathy patients when treated for 36 weeks. No statistically significant differences were observed between groups in the primary end point; adjusted percentage change in urinary albumin/creatinine ratio (UACR), which increased (mean T/V, 29.29%; mean B/A, 8.49%; difference, 20.80%; P =.34); or in change in absolute UACR, which decreased (mean [g/g] T/V, −0.11; mean [g/g] B/A, −0.08; difference −0.03; P =.78). There were significant reductions in log UACR (mean change in T/V, −0.28; P <.01; mean change in B/A, −0.31; P <.001) and diastolic blood pressure in both groups and in systolic blood pressure in the B/A group. T/V was not superior to B/A for reducing UACR. Both ACEI/CCB FDCs may reduce albuminuria; in the case of T/V, this appears to be independent of systolic blood pressure reduction in patients who had previously been treated and had baseline blood pressure levels of 142/77 mm Hg.