Correlation of 'in vitro' release and 'in vivo' absorption characteristicsof rifampicin from ethylcellulose coated nonpareil beads

The purpose of this study was to investigate the possibility to develop dif ferent levels of correlation between in vitro dissolution parameters and in vivo pharmacokinetic parameters for three rifampicin formulations. A level A correlation of in vitro release and in vivo absorption could be obtained for individual plasma level data by means of the Wagner and Nelson method. Linear correlation could be obtained when percent dose released in vitro w as plotted vs percent dose absorbed in vivo with correlation coefficients b etween 0.954, 0.983 and 0.997 for the formulations studied. A second level correlation between mean in vitro dissolution time (MDT) and mean in vivo r esidence time (MRT) was performed with a correlation coefficient of 0.536, 0.420 and 0.335. Finally, it was also possible to establish a good in vitro -in vivo correlation when the T-50%hrs (time taken to release 50% of rifamp icin) in vitro and C-max, T-max or AUC in vivo were compared. (C) 2001 Else vier Science B.V. All rights reserved.