Effect of crystal imperfections on the in-vitro release of theophylline microspheres

ABSTRACT

Theophylline sustained release microspheres were successfully prepared by applying the non-solvent addition method. The prepared microspheres were subjected to irradiation with Gamma rays at a dose of 100 kGy. The in-vitro release rate of the drug from the irradiated microspheres was studied and the effect of annealing after radiation was investigated. The results showed that the release of theophylline from microspheres was faster from the irradiated microspheres compared to the non-irradiated ones, that is because of the effect of radiation on both the drug and the polymer crystal lattice. The polymeric layer played a significant role of protecting the drug from being affected with Gamma rays. That effect retrieved after heating the irradiated microspheres to temperature [65 and 120°C] for 15 and 24 hours respectively