PROPERTIES OF IMPLANTABLE PELLETS PREPARED FROM A BIODEGRADABLE POLYESTER

Biodegradable pellets for implantation use were prepared from a naturally produced copolyester, poly(hydroxybutyrate-hydroxyvalerate) (PHBV), by a simple compression and melt technique. Progesterone was incorporated in the pellets. Differential scanning calorimetric (DSC) and scanning electron microscopic (SEM) examinations showed that the drug has limited solubility in the polymer and exists as crystals uniformly distributed in the matrix. However, the drug undergoes a polymorphic change during melting from alpha to beta-form. Ultraviolet and infrared spectrophotometric tests on melted drug and polymer samples detected no chemical degradation. In vitro release of the drug was faster when the amount of drug in the pellet was increased. The drug release could be slowed by increasing the the size of pellet.