The case for combining angiotensin-converting enzyme inhibitors and calcium-channel blockers.

Tight blood pressure control among diabetic and nondiabetic patients with hypertension is perhaps the single most effective intervention used to delay progression to end-stage renal disease (ESRD). The renoprotective actions of angiotensin-converting enzyme (ACE) inhibitors in patients with diabetic and hypertensive nephropathy is well established. Drugs of this class fairly uniformly reduce glomerulosclerosis, delay the deterioration in renal function, and improve proteinuria, a predictive surrogate marker for renal injury. Calcium- channel blockers (CCBs) in the phenylalkylamine (verapamil) and benzothiazepine (diltiazem) classes also improve proteinuria and delay the progression of renal disease in diabetic and nondiabetic hypertensive nephropathy beyond that attributable to blood pressure control. The short-acting dihydropyridine CCBs worsen proteinuria and accelerate renal injury in both animal models and humans with hypertension or diabetes. A very limited number of studies in animals or humans with hypertension or diabetes have demonstrated at least an additive renoprotective effect when the combination of ACE inhibitors and nondihydropyridine CCBs has been compared with each agent administered as monotherapy. Because patients with impaired renal function and either hypertension or diabetes appear to benefit from aggressive blood pressure reduction, many of these patients will require two or more drugs to achieve the currently recommended blood pressure goals. Combinations of ACE inhibitor and CCB are attractive because they may provide better blood pressure control, appear to be better tolerated with fewer side effects than either drug alone, and may exert a greater renoprotective effect in patients at risk for renal failure than either an ACE inhibitor or a CCB.