Moment Analysis for the Evaluation of In Vitro Drug Release and In Vivo Bioavailability of Theophylline Microcapsules

Abstract

Statistical moment analysis has been used to establish an in vitro-in vivo correlation for five types of theophylline ethylcellulose microcapsules prepared by using various concentrations of ethylene-vinyl acetate (EVA) copolymer as a coacervation-inducing agent. The concentration of EVA copolymer was found to be played an important function in the controlled release of theophylline microcapsules. Correlations were found between the in vitro dissolution behavior, e.g., MDT _0→7, in vitro' and the rate of bioavailability, e.g., Cmax, Tmax, MDT _{in vivo} or MRT_0→2, although there was no valid correlation with the extent of bioavailability, e.g., AUC_0→27. Thus, moment analysis by studying the quantitative in vitro-in vivo correlations relating to drug release was validated.