Preparation of Roxithromycin-Loaded Poly(l-lactic Acid) Films with Supercritical Solution Impregnation

Abstract

Supercritical solution impregnation (SSI) was applied to prepare drug-loaded biodegradable films where poly(l-lactic acid) (PLLA) was used as the matrix and roxithromycin as the model drug. The effects of impregnation time, operating temperature, and pressure on drug loading capacity (DLC) of roxithromycin into PLLA matrix were investigated. With the extension of impregnation time, DLC increased gradually to an equilibrium value. DLC was also affected by impregnation temperature and pressure. At the optimal condition, i.e., impregnating at 70 °C and 300 bar for 2 h, the maximal DLC was approximately 10.5%. After SSI process, the PLLA film was still transparent. The SEM images showed that the morphologies of PLLA film did not change with the SSI process. The DSC data and XRD spectra demonstrated that roxithromycin molecules were dispersed into the PLLA film in an amorphous state and the SCCO2 processed PLLA film had a lower crystal degree than raw PLLA film. The residual dichloromethane due to the PLLA film preparation could be removed effectively during the SSI process and meet the Chinese Pharmacopoeia limit. In vitro release of roxithromycin consisted of two stages: initial rapid release and a following slow release. The SSI process is expected to be a promising technique to prepare a drug-loaded biodegradable polymer surface and matrix for antibacterial therapeutic implants.