In-vitro, ex-vivo, and in-vivo release evaluation of in situ forming buprenorphine implants using mixture of PLGA copolymers and additives

AbstractAn in-situ forming implant of buprenorphine was prepared by combining PLGA RG756s and PLGA RG504H copolymers, and additives that decreased the initial burst release. The optimum formulation was achieved based on a minimum initial burst release of BP in the in-vitro release medium using a Box-Behnken design. The in-vitro, ex-vivo, and in-vivo release of the optimized formulation was investigated. The rabbit-blood concentrations of the optimized formulation and RBP-6000 (PLGA 504H) were compared to ensure their equivalency. The results indicate that the optimized formulation can reach an effective therapeutic concentration for treating opioid dependence with minimum initial burst release.