Antisolvent Coprecipitation of Biopolymers and Drugs

Controlled – delivery products are finding considerable attention, because of their drug’s therapeutic effect prolongation, that keeps the drug concentration in the body between a lower limit (therapeutic limit) and an upper limit (toxicity limit). These devices are traditionally obtained by encapsulation of a drug in a polymer matrix using an organic solvent with the following steps: • Solubilization of the active principle in an organic solvent; • Partitioning of the active principle between the solvent and the polymer matrix; • Residual solvent removal. Problems arise for the elimination of residual solvent to acceptable limits. Antisolvent precipitation can be an alternative method for the encapsulation of a drug in a polymer matrix. In this study the feasibility of the technique, known as Supercritical Anti Solvent recrystallization (SAS), will be investigated in order to obtain the co-precipitation of a drug and a biodegradable polymer from an appropriate organic solvent. A biodegradable polymer, poly(L-lactide) (L-PLA) is considered, with a non steroidal anti-inflammatory drug (NSAID), nimesulide, as active principle.