Controlled Release of Cyclosporine A from Biodegradable Amphiphilic Diblock Copolymer Sol-gel Drug Delivery System

Biodegradable sol-gel drug delivery systems containing cyclosporine A (CsA, cyclosporine) were prepared using methoxy (polyethylene glycol) and polyester diblock copolymers in aqueous solution. The diblock copolymers in aqueous solutions exhibited sol-gel transition behaviors with increasing temperature. The sol was formed by micelles. The micelle sizes of mPEG-PLGA and mPEG-PVLA were 70.8 nm and 67.1 rim, respectively. The sol-gel-sol transition phase diagrams were determined, as well as the variation of viscosity as a function of temperature. The maximum viscosities of the mPEG-PLGA and mPEG-PVLA gels were measured to be 11350 and 4420 cP, respectively. CsA was efficiently entrapped in both [methoxy(polyethylene glycol)-co-poly(lactic-co-glycolic acid)] (mPEG-PLGA) and [methoxy (polyethylene glycol)-co-poly(lactic-co-delta-valerolactic acid)] (mPEG-PVLA) sol-gel systems. Slow and sustained release of CsA was observed in vitro for both in situ gelling systems for 2 weeks.