The aim of this work was to develop a micropore-controlled release tablet for theophylline. The tablets were composed of a drug core surrounded by a microporous film. The major components of coating film included a biocompatible semipermeable polymer, cellulose acetate, and a water-soluble pore-forming agent, poly(ethylene glycol). The effect of the coating film composition and the type of excipient incorporated in the drug core on drug release were demonstrated via an in vitro release study. The optimized formulation was further investigated in vivo of rabbits. The results showed that micropore-controlled release tablets continuously released drug for 24-36 hours depending on the type of excipient in the drug core and the coating film composition. Incorporation
of lactose in the drug core enhanced drug release from micropore-controlled release tablets. In vivo animal study revealed that the
micropore-controlled release tablets reduced the maximum concentration and prolonged the mean residence time of drug.