Comparative dosing and efficacy of continuous-release nifedipine versus standard nifedipine for angina pectoris: clinical response, exercise performance, and plasma nifedipine levels.

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)