Biodegradation and antitumour effect of adriamycin-containing poly(L-lactic acid) microspheres

Adriamycin-containing poly (L-lactic acid) microspheres were prepared to develop a slow-releasing and long-acting adriamycin delivery system. An almost constant release of adriamycin from the adriamycin-containing poly(L-lactic acid) was achieved in Tris buffer and adriamycin disappeared within 20 d. Adriamycin was not detected in serum for up to 14 d, when the suspension of the adriamycin-containing poly(L-lactic acid) microspheres was injected into lung parenchyma, the femoral muscles of rabbits or the peritoneal cavity of mice. However, adriamycin remained in the rabbit muscles for up to 10 d under formation of scar tissue. When free adriamycin was added to P815 tumour cells in culture, the cell survival rate decreased with the exposure time. The treatment with the adriamycin-containing poly(L-lactic acid) microspheres showed a higher survival rate for mice bearing P815 tumour cells than with free adriamycin. In addition, the systemic side effects were insignificant when the adriamycin-containing poly(L-lactic acid) microspheres were given to mice instead of free adriamycin.