Investigation of the interaction between acidic,basic, neutral,and zwitterionic drugs with poly-<Emphasis Type="Italic">L</Emphasis>-lactic acid by thermal and analytical methods

This project investigated the interaction between poly-L-lactic acid (PLLA) and several therapeutic agents. Low percentage crystallinity PLLA (melt-pressed, molded and drawn) was studied. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) were used to characterize the crystallinity and thermal properties in a thermal cycling process. Repeatable melting and crystallization events were observed. The thermal properties of a drug-polymer combination using PLLA and an acidic, basic, neutral and zwitterionic material were investigated. A sufficient quantity of the drug must be present in the polymer to be observed thermally. Release of atropine sulfate from a PLLA tablet showed a two-phase process.