In-vivo degradation of poly(lactic acid) of different molecular weights.

Lactic acid was polymerized using tetraphenyl tin as a catalyst. The molecular weight of the resultant poly(lactic acid) varied between 0.89 X 10(6) and 2.94 X 10(6) depending upon the concentration of the catalyst used. In-vivo degradation of the poly(lactic acid) samples having 4 different molecular weights were studies by implanting these in Wistar rats. It was found that at the end of a 48-week implantation period lower molecular weight poly(lactic acid) samples were degraded at a faster rate than the higher molecular weight samples.