IN-VIVO CHARACTERISTICS OF INJECTABLE POLY(DL-LACTIC ACID) MICROSPHERES FOR LONG-ACTING DRUG-DELIVERY

Poly(DL-lactic acid) (PLA) microspheres containing testosterone (T) we re prepared by the solvent evaporation process to evaluate their-physi cal properties such as size distribution, shape, drug content, in vivo controlled drug release, pharmacological influences on the prostate g land in castrated rats, and histopathological findings of tissues surr ounding the implants. The in vivo release of T from PLA microspheres c ontaining 30 mg of drug obtained with chloroform was continued over a 6-week period. This effect is attributed to high dispersibility of T i n the device when obtained with chloroform. Both serum drug levels and prostate gland weight recovery suggested the effects of a long-acting drug delivery system. The histopathological findings showed that the devices used were completely degraded 10 weeks after injection.