Effect of an L- and T-Type Calcium Channel Blocker on 24-Hour Systolic Blood Pressure and Heart Rate in Hypertensive Patients

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 $16.7{\pm}6.1$% to $8.3{\pm}9.8$% (p<0.05), whereas in non-dipper hypertension cases, it increased from $2.3{\pm}2.9$% to $7.7{\pm}5.1$% (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 (2.1mm Hg/h) and a non-administration time dependent reduction in 24-hour HR.