Supercritical Co2 Processing of Drug Loaded Membranes Based on Nanoporous PVDF-HFP Aerogels

One of the alternatives proposed to obtain controlled release pharmaceutical formulations is the generation of membranes loaded with an active principle; until now, several methods have been proposed, but all these techniques present various limitations. The production of loaded membranes based on aerogels has also been tested, but several problems are still open due to the possible drug stratification and to the collapse of the porous structure during the drying process. In this work, we tested a supercritical CO2 (SC-CO2) drying process for the formation of PVDF-HFP loaded aerogels. We performed experiments at pressures ranging between 150 and 250 bar and at temperatures ranging between 35 and 55 degrees C. We selected the PVDF-HFP-acetone-ethanol solution at 15% w/w polymer and modified the drug (amoxicillin) concentration from 20 to 30% w/w with respect to PVDF-HFP as the base case. The SC-CO2 drying process was confirmed to be a valid alternative to generate loaded structures; indeed, aerogels characterized by nanometric networks (mean pores diameter of about 300 nm) with homogeneous drug distribution were obtained. Drug controlled release experiments were also performed and a quasi-zero order release kinetic was observed.