Preparation and evaluation of chitosan-alginate/carrageenan hydrogel for oral drug delivery in the treatment of diabetes

Marine beds are an untapped resource of bioactive materials which can be explored for drug delivery applications. In the present study, a hydrogel was developed with an optimal concentration of sodium alginate-chitosan core polyelectrolytic complex loaded with anti-diabetic drug metformin and coated with kappa-Carrageenan as an efficient oral drug delivery vehicle. The formulation was optimized by changing parameters such as concentration of polymers, amount of cross-linker and the type and amount of coating material. The prepared hydrogels were characterized for their structural integrity using instrumental techniques such as FTIR, XRD, DSC, and SEM while the physical properties were assessed by evaluating its thickness, UV barrier ability and swelling degree. In vitro study demonstrated the influence of presence and type of coating material affecting drug delivery process. The study suggested that coating with 3% kappa-Carrageenan (A19) was found most suitable for oral drug delivery since it could resist diffusion of drug in the stomach (pH 1.2) so that maximum drug could reach the intestine (pH 7.4) for absorption. Metformin loaded hydrogel (A20) released similar to 49% drug in the simulated gastric fluid (pH 1.2). In the simulated intestinal fluid (pH 7.4) both the hydrogel exhibited a sustained release pattern lasting for more than 4 h. Investigation of drug release kinetics using different mathematical models showed that Higuchi model was the best fit release model with R-2 >= 0.973. The results indicated that the prepared hydrogels could be potential drug delivery vehicle toward intestine as well as for extended release to colon targeted drug delivery.