Plasticization of biodegradable polymers for use in controlled release.

The design of a plasticized, biodegradable polymeric material, suitable for application as a controlled-release system, was attempted. A poly(DL-lactic acid) oligomer was plasticized with 1,2-propylene glycol and glycerol. The latter plasticizer showed poor compatibility whereas 1,2-propylene glycol was compatible with the polymer up to high concentrations. The mixtures prepared displayed considerable depression of processing temperature and enhanced delivery of salicylic acid, in the early stages of release. It seemed, therefore, feasible to produce systems which allow easy and safe processing and can be injected into a body cavity, without the need for surgical retrieval after completion of the release. Furthermore, the differential rate of drug delivery might be of profound interest for cases where elevated drug doses are necessary in the beginning of treatment.