COMPARISON OF 24-HOUR BLOOD-PRESSURE, HEART-RATE, AND AUTONOMIC NERVEACTIVITY IN HYPERTENSIVE PATIENTS TREATED WITH CILNIDIPINE OR NIFEDIPINE-RETARD

We compared the effects of cilnidipine and nifedipine retard on 24-h b lood pressure (BP), heart rate (HR), and autonomic nerve activity in p atients with essential hypertension. Cilnidipine is a novel and unique 1,4-dihydropyridine calcium antagonist that has the L-type and N-type voltage-dependent calcium channel-blocking action. Fourteen hypertens ive outpatients (four men and 10 women; aged 64 +/- 2 years, mean +/- SEM) were enrolled in this study. Their ambulatory BP and electrocardi ogram were monitored for 24 h at intervals of 30 min with a portable r ecorder after a 4-week drug-free period, after a 4-week treatment peri od with cilnidipine (5 or 10 mg once daily), and after a 4-week treatm ent period with nifedipine retard (10 or 20 mg twice daily). The order of the three periods was randomized. Autonomic nerve activity was eva luated by a power spectral analysis of HR variability, by using the hi gh-frequency (HF) component as an index of parasympathetic nerve activ ity and the ratio of the low-frequency (LF:) component to the HF compo nent (LF/HF) as an index of sympathovagal balance. Cilnidipine and nif edipine retard significantly reduced the 24-h BP of these patients to similar extents (:cilnidipine, -11 +/- 3/-6 +/- 1 mm Hg; nifedipine re tard, -15 +/- 3/-6 +/- 2 mm Hg). Cilnidipine did not change the 24-h a verage HR, whereas nifedipine retard significantly increased it (+3.3 +/- 1.4 beats/min; p < 0.05). Nifedipine retard significantly increase d the LF/HF ratio in the daytime and the nighttime. Such changes were limited to the daytime in the treatment period with cilnidipine. These results suggest that cilnidipine is effective as a once-daily antihyp ertensive agent and had less influence on autonomic nervous system and HR than did nifedipine retard.