To assess the dosing equivalency and the early and late antianginal efficacy of a gastrointestinal therapeutic system for once-daily, continuous-release
nifedipine (N-GITS), 10 patients with
stable angina pectoris, who were previously receiving chronic treatment with
nifedipine, completed a 12-week trial comparing N-GITS with standard
nifedipine. All patients (nine men and one woman; mean age 54 +/- 2 [SEM] years) who were receiving standard
nifedipine (mean dose 40 +/- 5 mg/24 hr) for more than 2 weeks (mean 8 +/- 2 months, range 2 to 36 months) were switched to an equivalent once-daily dose (39 +/- 5 mg/24 hr) of N-GITS. Standard
nifedipine and N-GITS were compared by symptom-limited exercise treadmill tests with a baseline test (A) performed 3 hours after a standard dose of
nifedipine. Exercise tests were also performed after 2 weeks of treatment with N-GITS 3 hours (B) and 24 hours (C) after the
drug was given, and after 12 weeks of treatment with N-GITS, 24 hours after dosing (D). Results of exercise tests showed no significant difference in mean exercise time--(A) 422 +/- 25 vs (B) 426 +/- 36 vs (C) 438 +/- 35 vs (D) 487 +/- 37 seconds. Likewise, there was no significant mean difference in peak double product, resting heart rate, peak exercise heart rate, or resting or maximal systolic blood pressure for any of the exercise test points. Furthermore, five patients (50%) reported side effects with standard
nifedipine (all
vasodilator-
flushing,
dizziness, or both), which resolved
after treatment with N-GITS (p +/- 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)