High encapsulation efficiency of poloxamer-based injectable thermoresponsive hydrogels of etoposide

Hydrogels are promising polymeric network capable of sustaining the release of drug but have a major limitation for encapsulation of hydrophobic drugs.This study was undertaken to encapsulate etoposide in poloxamer 407-based thermosensitive hydrogels with an aim to sustain its release.Etoposide-loaded hydrogels were prepared by the cold method and optimized for encapsulation efficiency (EE) by a 3(2) factorial design. Poloxamer 407-poloxamer 188 hydrogel (E-P407-P188) and poloxamer 407-poly(ethylene glycol) (E-P407-PEG) hydrogel were characterized for SEM, swelling, sol-gel phase transition and injectability study.In E-P407-P188 hydrogel the EE of 75% could be obtained and in E-P407-PEG hydrogels the EE was 84%. The SEM images showed a porous structure. The release of ETO was sustained up to 48 h by E-P407-PEG hydrogel and 24 h by E-P407-P188 hydrogel. The drug release was governed by first-order kinetics and followed Fickian diffusion mechanism in both the cases.Such injectable thermosensitive hydrogel of etoposide could be effectively used for continuous release of drug to the tumor and surrounding tissues.