Blood pressure reduction and tolerability of amlodipine versus nifedipine retard in Chinese patients with type 2 diabetes mellitus and hypertension: a randomized 1-year clinical trial.

Objective: In this 1-year clinical study, we compared the efficacy and tolerability of amlodipine and nifedipine retard in 64 Chinese Type 2 diabetic patients with hypertension.
Subjects and Methods: There were 25 (39.1%) men and 39 (60.9%) women with mean age 60.7+/-9.9 years. Thirty-four patients were randomized to receive amlodipine 5 mg daily and 30 to receive nifedipine retard 20 mg twice daily. The daily dose of amlodipine and nifedipine retard was increased from 5 mg to 10 mg daily and 20 mg to 40 mg twice daily, respectively, if sitting BP > 140/90 mmHg.
Results: Of the 64 patients, 9 dropped out early because they experienced adverse effects related to the drugs. If all treatment-related adverse effects were taken into account, 6 (19.4%) patients were from the amlodipine group and 14 (53.8%) from the nifedipine group (p = 0.011). After 1 year, 48 patients finished the study, 28 were on amlodipine and 20 were on nifedipine retard. Of the 28 patients from the amlodipine group, 11 (39.3%) required additional antihypertensive agents. Of the 20 patients from the nifedipine group, 5 (25%, p value: NS, comparing the 2 groups) required additional antihypertensive agents. Both groups showed similar and significant reduction in blood pressure from Week 6 to Week 52.
Conclusion: Both amlodipine and nifedipine retard are relatively safe and useful in the treatment of hypertension in Chinese Type 2 diabetic patients. Nifedipine retard, when compared to amlodipine, showed significantly more adverse effects and these may hamper long-term compliance.