Effects of cilnidipine, a novel dihydropyridine calcium antagonist, on autonomic function, ambulatory blood pressure and heart rate in patients with essential hypertension

Abstract

Aims: The aim of the present study was to evaluate the effects of cilnidipine, a novel dihydropyridine calcium antagonist, on autonomic function, ambulatory blood pressure and heart rate in patients with essential hypertension. Methods: Ten inpatients with mild to moderate essential hypertension (four men and six women; age: 44-64 years) underwent a drug-free period for 7 days and a treatment period with cilnidipine 10 mg orally for another 7 days, in a randomized crossover study. On the sixth day of each period, they underwent autonomic function tests including a mental arithmetic test, a cold pressor test and a Valsalva manoeuvre. After these tests, 24 h ambulatory blood pressure, heart rate, and the electrocardiogram R-R intervals were monitored every 30 min. A power spectral analysis of R-R intervals was performed to obtain the low-and high-frequency components. Results: Cilnidipine significantly decreased the 24 h blood pressure by 6.5 ± 1.7 mmHg systolic (mean ± s.e.mean; P < 0.01) and 5.0 ± 1.1 mmHg diastolic (P < 0.01), whereas cilnidipine did not change heart rate or any indices of power spectral components. During the cold pressor test, the maximum change in systolic blood pressure and percentage changes in both systolic and diastolic blood pressures were significantly lower during the treatment period with cilnidipine than during the drugfree period. The baroreflex sensitivity measured from the overshoot phase of the Valsalva manoeuvre did not differ significantly between the two periods. Conclusions: Cilnidipine is effective as a once-daily antihypertensive agent and causes little influence on heart rate and the autonomic nervous system in patients with mild to moderate essential hypertension. Moreover, it is suggested that cilnidipine has an additional clinical benefit in the inhibition of the pressor response induced by acute cold stress.