BIOAVAILABILITY FROM FELODIPINE EXTENDED-RELEASE TABLETS WITH DIFFERENT DISSOLUTION PROPERTIES

The objective of the present study was to investigate the relationship between in vitro dissolution and absorption of felodipine, a calcium antagonist of the dihydropyridine type, from three types of extended-release (ER) tablet. Felodipine was released in vitro over 6, 12 and 20 h, respectively. The tablets were studied in vivo after a single oral dose in a cross-over study in 16 healthy and informed volunteers. A completely absorbed oral solution served as reference. Statistical moment and deconvolution analyses were performed. The slower the drug release, the lower was the peak plasma level and the longer the time to peak. Only the slowest releasing tablet had a reduced extent of bioavailability. There was a good correlation between tablet dissolution in vitro and in vivo. The results indicate that the absorption of felodipine from the gastrointestinal tract can continue for up to 20 h after administration. © 1990.