Crystalline poly-D(-)-3-hydroxybutyrate (PHB) and its copolymers with poly-3-hydroxyvalerate [P(HB-HV)] are biodegradable polyhydroxyalkanoates with potential application in controlled drug delivery systems. Matrices of PHB and P(HB-HV) copolymers containing a model drug, methyl red, were prepared by solvent casting and melt-processing. Drug release from P(HB-HV) copolymer matrices produced by any given fabrication technique was dependent on copolymer composition. Progressively faster rates of drug release were obtained on increasing HV content. This could be explained by the different crystallization behaviour of P(HB-HV) copolymers. Evidence from polarized light microscopy of copolymer spherulites suggests that copolymer films with increasing HV content exhibit morphologies with decreasing abilities to entrap the model drug.
- Crystalline morphology
- Drug release