摘要
1 INTRODUCTIONThe release of a drug from a diffusional matrix has been investigated by variousresearchers for different conditions [1-4].The drug loading in the matrix may beabove or below its solubility limit.If it is beyond,the release boundary is generated bythe dissolution of drug,and the concentration in the released region may be propor-tional to the distance and kept at saturation in the unreleased region.Otherwise。
