title: Comparison of once-daily nifedipine controlled-release with twice-daily nifedipine retard in the treatment of essential hypertension.
abstract: OBJECTIVE
  Nifedipine is a short-acting calcium antagonist formulated into several different oral preparations, each of which may have different effects on haemodynamics and autonomic nervous function. We compared the effects of nifedipine controlled-release (CR) and nifedipine retard on 24-h blood pressure, heart rate, rate-pressure product, and power spectral measures of heart rate variability in patients with essential hypertension.
  
  
  METHODS
  After 4 weeks of a drug-free period, 25 patients were randomized to receive either once-daily treatment with nifedipine CR (20-40 mg daily; 12 patients) or twice-daily treatment with nifedipine retard (20-40 mg daily; 13 patients) for 12 weeks. The ambulatory blood pressure, heart rate, and ECG R-R intervals were measured during a 24-h period using a portable recorder (TM-2425) at the end of the drug-free and the treatment periods. A power-spectral analysis of R-R intervals was performed to obtain the low-frequency (LF) and high-frequency (HF) components.
  
  
  RESULTS
  Nifedipine CR and nifedipine retard reduced 24-h blood pressure significantly by 15.9 +/- 3.2 (SE)/8.7 +/- 1.4 mmHg and by 10.9 +/- 2.8/9.4 +/- 1.7 mmHg, respectively, after the 12-week treatment. Nifedipine CR did not change the 24-h heart rate significantly, while nifedipine retard increased it significantly by 3.9 +/- 2.1 beats min(-1). Nifedipine CR produced a significant reduction in rate-pressure product throughout a 24-h period, while nifedipine retard did not change the rate-pressure product significantly. In addition, nifedipine retard significantly decreased the 24-h and daytime average values of the LF and HF components, while nifedipine CR affected the nighttime LF component alone and did not change the HF component throughout a 24-h period.
  
  
  CONCLUSIONS
  These results demonstrate that both nifedipine CR and nifedipine retard are effective as antihypertensive agents, but nifedipine CR has less influence on the autonomic nervous system and heart rate than nifedipine retard.
authors.affiliation: Department of Hypertension and Cardiorenal Medicine, Dokkyo University School of Medicine, Mibu, Tochigi, Japan. j-minami@dokkyomed.ac.jp
authors.forename: Junichi
authors.initials: J
authors.lastname: Minami
authors.forename: Atsushi
authors.initials: A
authors.lastname: Numabe
authors.forename: Norikazu
authors.initials: N
authors.lastname: Andoh
authors.forename: Naohiko
authors.initials: N
authors.lastname: Kobayashi
authors.forename: Shigeo
authors.initials: S
authors.lastname: Horinaka
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Ishimitsu
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Matsuoka
mesh_terms: D000328:Adult; D000368:Aged; D001341:Autonomic Nervous System / Q000187:drug effects; D001794:Blood Pressure; D003692:Delayed-Action Preparations; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D006973:Hypertension / Q000188:drug therapy* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009543:Nifedipine / Q000008:administration & dosage*; D014665:Vasodilator Agents / Q000008:administration & dosage*
chemical_list: D003692:Delayed-Action Preparations; D014665:Vasodilator Agents; D009543:Nifedipine