Bioavailability of nifedipine: a comparison between two preparations.

In a random cross-over study, eight healthy volunteers received single 10 mg doses of either nifedipine capsule (Adalat, Bayer) or nifedipine tablets (Taro) after an overnight fast. The areas under the serum concentration time curves were not significantly different (AUC0----infinity 319.8 +/- 28.0 (SEM) ng ml-1 h-1 for capsules, 260.8 +/- 15.3 ng ml-1 h-1 for tablets). The peak serum levels and the time of their occurrence were 162.4 +/- 23.4 ng ml-1 at 30 min for capsules and 43.0 +/- 3.0 ng ml-1 at 1-2 h for tablets, indicating that the absorption of nifedipine from the capsule is faster than from the tablet form. Clinical symptoms of vasodilation corresponded with the nifedipine peak levels. We conclude that although the bioavailability in general of the two preparations is similar, the therapeutic equivalence may differ. Depending on the therapeutic indication each preparation may have its merits.