Supercritical Phase Inversion To Form Drug-Loaded Poly(vinylidene fluoride-co-hexafluoropropylene) Membranes

Membranes loaded with ail active principle are one of the alternatives proposed to obtain controlled release pharmaceutical formulations. Until now, several methods have been proposed for the fabrication of membranes as drug delivery devices, Such as phase inversion, gas foaming/particulate leaching, and solvent evaporation. Supercritical CO2 (SC-CO2) phase inversion offers an alternative process to obtain solvent-free membranes with short processing times, avoiding the collapse of the structure. We prepared poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) loaded membranes by SC-CO2 phase inversion, performing experiments at pressures ranging between 150 and 250 bar and at temperatures ranging between 35 and 55 degrees C. We selected as the base case the PVDF-HFP-acetone Solution at 15% w/w polymer and modified the drug (amoxicillin) concentration from 20 to 50% w/w with respect to PVDF-HFP. Different membranes morphologies, ranging from nanometric gel-like networks (mean pores diameter of about 150 nm) to micrometric cellular structures (mean cells diameter ranging between 5 and 12 mu m), and different drug distributions were obtained, depending on the process conditions. Drug-controlled release experiments were also performed to study the kinetics and duration of the release process.