In a comparison of the effects of cilnidipine and nifedipine retard on 24-h blood pressure (BP), heart rate (HR), and autonomic nerve activity in patients with essential hypertension, 14 outpatients were enrolled. The ambulatory BP and electrocardiogram were monitored for all patients for 24 h at intervals of 30 min after a 4-week drug-free period, after a 4-week treatment period with cilnidipine (5 or 10 mg once daily), and after a 4-week treatment period with nifedipine retard (10 or 20 mg twice daily). Cilnidipine and nifedipine retard were found to significantly reduce the 24-h BP of these patients to similar extents (cilnidipine, -11 +/- 3/-6 +/- 1 mmHg; nifedipine retard, -15 +/- 3/-6 +/- 2 mmHg). While cilnidipine did not change the 24-h average HR, nifedipine retard was noted to significantly increase it (+3.3 +/- 1.4 beats/min). Nifedipine retard significantly increased the low-frequency (LF) component to the high-frequency (HF) component [LF/HF] ratio in the daytime and the night-time. Such changes were limited to the daytime with cilnidipine.

The results, published in the Journal of Cardiovascular Pharmacology, thus suggested that cilnidipine is effective as a once-daily antihypertensive agent and exerts less influence on autonomic nervous system and HR as compared to nifedipine retard.