Comparison of clinical efficacy and adverse effects between extend- release felodipine and slow-release diltiazem in patients with isolated systolic hypertension

Background: Isolated systolic hypertension (ISH) is a risk factor for cardiovascular disease. Extended-release felodipine (felodipine ER) has been shown to be effective in the treatment of ISH in Caucasians. However, its pharmacological properties are different from another calcium blocker, diltiazem. Also, the effectiveness, tolerability, and adverse reactions of these two antihypertensive agents for ISH have not been thoroughly assessed in Chinese. Methods: Sitting blood pressures (BP), heart rate, body weight, adverse reactions, and serum biochemistry were assessed in 70 patients with isolated systolic hypertension (34 treated with felodipine ER and 36 slow- release diltiazem [diltiazem SR] for 10 weeks). Each patient was given 5 mg of felodipine ER or 90 mg of diltiazem SR once daily and was doubled to twice daily if necessary. Results: Five patients on felodipine ER and four on diltiazem SR withdrew because of intolerable side effects. By ten weeks, 67.6% of the patients responded to a daily dose of 5-10 mg of felodipine ER and 58.3% to a daily dose of 90-180 mg of diltiazem SR. At the end of treatment, felodipine ER lowered the mean BP from 187/83 mmHg at baseline to 149/74 mmHg, whereas diltiazem SR decreased the BP from 185/84 mmHg to 158/78 mmHg (not significant between the two groups). The heart rate did not change significantly in either group. Overall, these two groups of patients had the same rate of adverse reactions (50.0% vs 50.0%) with similar profiles of the adverse effects. Conclusion: Equivalent doses of felodipine ER and diltiazem SR are effective first-line monotherapeutic agents for the treatment of ISH.