Comparison between Two Calcium Antagonists: Blood Pressure Reduction and Renal Effects in Hypertensive Patients with Type 2 Diabetes

Several types of Ca channel blockers (CCBs) which have unique organ protective effects are commercially available all over the world. However, the hypotensive and pleotropic effect in CCBs are not sufficiently assessed in the diabetic patient with refractory hypertension for angiotensin receptor blocker (ARB). We conducted a pilot study to compare the efficacy of two different CCBs (azelnidipine and nifedipine controlled release (CR)) in 55 hypertensive patients with type 2 diabetes who had not achieved their target blood pressure (BP) with ARB monotherapy. Patients were randomly assigned to receive azelnidipine (8–16 mg/day) or nifedipine CR (10–40 mg/day) concomitantly with valsartan (80 mg/day). There were no significant differences in baseline characteristics between the two groups. The final dose of azelnidipine and nifedipine CR was 13.3±3.9 and 17.1±9.4 mg/day, respectively. However the target BP (<130/80mmHg) achievement rate was higher in the earlier phase of the combination therapy with nifedipine CR than that of the azelnidipine group, the rates after 6 months were comparable between the groups (83 vs. 66%). The systolic blood pressure was significantly lower in the nifedipine CR group from 2 to 6 months after the combination therapy (P<0.05, respectively). Both groups showed no significant changes in blood glucose and hemoglobin A1c. There were no significant differences in the urinary albumin/creatinine ratio and estimated Glomerular Filtration Rate (eGFR). In conclusion, the adjunctive therapy of nifedipine CR was superior to that of azelnidipine for decreasing blood pressure and achieving the target blood pressure, especially in the earlier phase of the diabetic patient with refractory hypertension for ARB. However the nephroprotective effect of nifedipine CR combination therapy was comparable to that of azelnidipine.