In vitro release behaviour of theophylline from PIB-induced ethylcellulose microcapsules interpreted by simple mathematical functions

Abstract

Theophylline microcapsules were prepared by phase separation using polyisobutylene as a coacervation-inducing agent. The release rate was dependent on the molecular weight of the polyisobutylene used. A simple mathematical function has been used for the quantitative description of the release process of the drug from PIB-induced microcapsules. It was found that 1/y = A(1/x)+ B is the best for interpreting the release process of microcapsules, since the values of the constants A and B are proportional to the amount of the drug released.