DESIGN AND CHARACTERIZATION OF A BIOCOMPATIBLE PHYSICAL HYDROGEL BASED ON SCLEROGLUCAN FOR TOPICAL DRUG DELIVERY.

Physical hydrogels of a high-carboxymethylated derivative of scleroglucan (Scl-CM) were investigated as potential systems for topical drug delivery using three different therapeutic molecules (fluconazole, diclofenac and betamethasone). Rheological tests were carried out on drug-loaded hydrogels along with in-vitro release studies in a vertical Franz cell, in order to investigate if and how different drugs may influence the rheological and release properties of Scl-CM hydrogels. Experimental results and theoretical modeling highlighted that, in the absence of drug/polymer interactions (as for fluconazole and betamethasone) Scl-CM matrices offer negligible resistance to drug diffusion and a Fickian transport model can be adopted to estimate the effective diffusion coefficient in the swollen hydrogel. The presence of weak drug/hydrogel chemical bonds (as for diclofenac), confirmed by frequency sweep tests, slow down the drug release kinetics and a non-Fickian two-phase transport model has to be adopted. In-vivo experiments on rabbits evidenced optimal skin tolerability of Scl-CM hydrogels after topical application.