Effect of an L- and T-type calcium channel blocker on 24-hour systolic blood pressure and heart rate in hypertensive patients

Abstract

Background and objectives: The aim of this study was to evaluate the effects of an L- and T-type calcium channel blocker (CCB) on 24-hour systolic blood pressure (24-hour SBP) and heart rate (24-hour HR) profiles in essential hypertensive patients.

Subjects and methods: Thirty-seven consecutive patients were enrolled in this study. The 24-hour SBP and HR were recorded before and after treatment with efonidipine (L- and T-type CCB, 40 mg), after waking. Changes in 24-hour SBP and HR and the diurnal to nocturnal SBP ratio were measured. The best-fit curves of changes in SBP and HR were depicted using a periodic function.

Results: The mean 24-hour SBP and HR decreased significantly after treatment. The diurnal to nocturnal SBP ratio in dipper-type hypertension cases decreased from 16.7±6.1% to 8.3±9.8% (p<0.05), whereas in non-dipper hypertension cases, it increased from 2.3±2.9% to 7.7±5.1% (p<0.01). The antihypertensive effect was minimal at 5.0 hours after drug administration and it slowly recovered at a constant rate (2.1 mm Hg/h) over 12 hours in dipper cases. The median 24-hour changes in HR in the dipper and non-dipper cases were -2.3/min and -5.4/min, respectively. A continuous reduction in the change in HR was seen from 3.5 to 23 hours after drug administration.

Conclusion: The antihypertensive action of efonidipine was characterized by a slow recovery of the SBP decrease at a constant rate (2.1 mm Hg/h) and a non-administration time dependent reduction in 24-hour HR.

Keywords: Blood pressure; Calcium channel blockers; Heart rate; Hypertension.

Fig. 1

Alterations in systolic blood pressure (SBP) and heart rate (HR) over 24-hour periods before and after efonidipine administration. A: each 30-minute average value of SBP and HR over a 24-hour time period, measured in patients whose average 24-hour SBP fell by 5 mm Hg or more after administration of the drug (n=29). B: each 30-minute average value of SBP and HR over a 24-hour period measured, in patients whose average 24-hour SBP did not fall after administration of the drug (n=8). The gray shaded horizontal bars in each graph represent the average nocturnal period (10:30 p.m. to 6:30 a.m.) in this study. : average systolic blood pressure before drug administration, : average systolic blood pressure after drug administration, : average heart rate before drug administration, : average heart rate after drug administration. Each value represents an average value±SD. ^*p<0.05, ^†p<0.01.

Fig. 2

Changes in diurnal systolic blood pressure (SBP), nocturnal SBP, and diurnal/nocturnal SBP ratio (D/N SBP ratios) in dipper and non-dipper type of hypertensives. In the upper graphs in both groups, the white columns indicate the mean diurnal SBP, and the gray columns indicate the mean nocturnal SBP before and after treatment with efonidipine in dipper cases (n=32) and non-dipper cases (n=5). The D/N SBP ratios are illustrated in the lower panels in both groups. The values expressed in this figure are the mean±SD. After: after treatment, Before: before treatment, (D-N)/D: (mean diurnal SBP-mean nocturnal SBP)/mean diurnal SBP.

Fig. 3

Changes in 24-hour ΔSBP and ΔHR after treatment with efonidipine in dipper and non-dipper cases. The best-fit curves of ΔSBP (upper graph) and ΔHR (lower graph) are shown, where black lines indicate the best-fit curves in dipper cases, and gray lines indicate non-dipper cases. The dotted longitudinal lines indicate the maximum or minimum value in the best-fit curves. Night-time is illustrated by closed transverse bars. The actual values of periodic parameters are illustrated on the right side of the figure. ΔSBP: difference in systolic blood pressure before and after medication every 30 minutes during a day, ΔHR: difference in heart rate before and after medication every 30 minutes during a day, Max: maximum value of the best-fit curve, Min: minimum value of the best-fit curve.