Sustained Release of Insulin from Poloxamer Gels Interpenetrated by Polyion Complexation of Chitosan-Hyaluronic Acid Network

This study investigates in vitro the protein drug delivery characteristics of new thermal sensitive gels, poloxamer P- chitosan CS/ hyaluronic acid HA gels P-CS/HA, in which a CS solution is interacting with various concentrations of HA that interpenetrates P gels. The polyion complexation occurs between CS and HA that can protect drugs from proteolysis. The results indicate that the swelling ratios of all P-CS/HA gels are markedly superior to those of nonswelling P and P- CS gels. For example, P-CS/HA 0.5% w/w gels have swelling ratios of 48.3 +/- 2.7% w/w, which are maintained for approximately 0.5 h in water at 37 degrees C. In vitro releases of insulin from P-CS/HA 0.5% w/w gels had significantly lowered initial burst release P < 0.01 and lasted much longer than those from gels without a CS network . The duration of insulin release was in a significantly sustained manner for up to 3.5 h, which was about two times or longer than the period of delivery using P or P-CS gels