Effect of azelnidipine on sympathetic nerve activity and baroreflex control in the patients with hypertension

Purpose: A new long-acting L-type Calcium channel blocker, azelnidipine, is reported not to increase the heart rate. However, it has not been determined whether long-term treatment of azelnidipine for hypertension in human has the effects on sympathetic nerve activity and baroreflex sensitibity (BRS) or not. The aim of this study was to determine the effect of azelnidipine on sympathetic nerve activity and BRS. Method: We studied 5 hypertensive patients treated with 8mg azelnidipine and 5 hypertensive patients treated with 16mg azelnidipine. Before the treatment and 3 months after the treatment, we measured the blood pressure (BP), BRS (in Tilt test), heart rate variability (HRV), and BP variability (BPV). Result: After 3 months, systolic BP and the null low-frequency component of systolic BPV (LFnuSBP), as the parameter of sympathetic nerve activity, were significantly decreased in both azelnidipine 8mg group (SBP; 156 ± 12 to 131 ± 4mmHg, LFnuSBP; 56 ± 4 to 50 ± 3% , n = 5, p < 0.05) and azelnidipine 16mg group (SBP; 160 ± 8 to 118 ± 8mmHg, LFnuSBP; 62 ± 5 to 51 ± 4% , n = 5, p < 0.05). The levels of the decreases in SBP and LFnuSBP were significantly greater in azelnidipine 16mg group than in azelnidipine 8mg group (SBP; -16% vs -26% , LFnuSBP; -11% vs -18% , n = 5 for each, p < 0.05). The high-frequency component of HRV, as the parameter of parasympathetic nerve activity, was not significantly changed in both group. BRS, which was impaired in the patients with hypertension, was significantly improved in azelnidipine 16mg group (13.8 ± 2.8 to 19.8 ± 4.1ms/mmHg, n = 5, p < 0.05). Conclusion: These results suggest that 3 months treatment with 16mg azelnidipine for hypertension has the sympatho-inhibitory effect and improve the baroreflex control.