Supercritical Carbon Dioxide Assisted Loading of Drug Eluting Medical Implants for Sustained Release

Biodegradable polymers impregnated with supercritical carbon dioxide (scCO2)–soluble therapeutic drug, free of solvent residue and artefacts, are found to be beneficial as medical implants for sustained release. The proposed work involves preparation of such an implant to investigate the effects of the characteristics of the three-component system, namely, CO2-polymer matrix-API on the drug loading, followed by mathematical modelling.  The efficiency of the loading process is usually measured as the partition coefficient of the drug between the polymeric phase and the scCO2 phase. The impregnation is a three-step process: (i) dissolution of drug in scCO2 and contacting the solution and the polymer, (ii) CO2 sorption in the polymeric matrix and diffusion of drug molecules into the swollen polymeric matrix, and (iii) depressurisation to recover the drug-loaded polymer.  The loading efficiency is analyzed by studying the effects of temperature, pressure, contact time, diffusivity of the drug into the polymer.