Article date: May 2008
By: Morris J. Brown, Corey B. Toal, in Volume 65, Issue 5, pages 646-652
WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT
AIMS
The haemodynamic responses to nifedipine vary between short‐ and long‐acting formulations. However, the latter have not been compared despite marked differences in their constitution. Our 1‐month randomized, crossover study was designed to compare the 30‐mg osmotic, constant‐release nifedipine gastrointestinal therapeutic system (N‐GITS) with an encapsulated mini‐tablet Coracten XL.
METHODS
Forty‐four hypertensive patients aged 63 ± 7 years were studied. The formulation was changed on day 15 and (for a single dose) day 30. At days 0, 14, 15, 29 and 30, patients were monitored for 6 h after dosing, during which blood pressure (BP), heart rate (HR) and plasma levels of norepinephrine (NE) and nifedipine were measured. The primary outcome was the difference in plasma NE between formulations at the time of peak nifedipine level.
RESULTS
Systolic BP decreased rapidly after the first dose of Coracten, achieving nadir at 5 h. HR rose by 1.2 ± 8.8 beats min−1. After N‐GITS HR fell by 2.4 ± 7.7 beats min−1 (P = 0.159). Plasma NE was higher in the Coracten‐ (480 ± 38.3 pg ml−1) than N‐GITS‐treated patients (343 ± 75.0 pg ml−1) at the time of peak nifedipine concentrations (4 and 5 h, respectively) and their change from baseline was significantly (P = 0.0046) different. A similar difference between the drugs was seen again at days 15 and 30, at 5 h after switching formulations.
CONCLUSIONS
This study suggests that two different formulations of once‐daily nifedipine result in different BP and plasma NE responses, and that switching between formulations causes opposite effects upon the sympathetic nervous response to falling BP.
DOI: 10.1111/j.1365-2125.2007.03082.x
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