Preparation of poly(acrylic acid)/linseed mucilage/chitosan hydrogel for ketorolac release

Studies of smart and biocompatible hydrogels have resulted in the development of efficient drug-delivery systems controlled by external stimuli. Taking inadequate doses of ketorolac could cause health complications in humans. Therefore, it is necessary the development of a polymeric matrix for controlled drug delivery to extend the release of Ketorolac. In this work, acrylic acid was polymerized using ammonium persulfate as initiator and N,N '-methylenebisacrylamide as a cross-linking agent, and in the presence of chitosan (Chit) and linseed mucilage (LS) biopolymers to obtain a composite of PAAc/LS/Chit hydrogel which was used for adsorption and release of ketorolac. Hydrogel was characterized by cryo-scanning electron microscopy (Cryo-SEM), Fourier transform infrared spectroscopy, and thermogravimetric analysis. The effects of pH on water hydrogel swelling percentage (S), water absorption percentage (W), and ketorolac-releasing kinetics were studied. SEM analysis showed hydrogel pore size pH-depending, with micropore diameters ranging between 5 and 10 nm at acidic pH, while for the hydrogel swollen at pH = 9, bigger pores are observed in the range of 30 to 50 nm. It was observed that S and W increased with the pH of the medium with an S of 608% at a pH of 9 following a Fickian behavior of water diffusion into the hydrogel pore and swelling kinetics represented by a second-order model. Ketorolac kinetic release was well described through the Korsmeyer-Peppas mathematical model, with the release rate increasing with the pH, extending the total release time of drug to 20 h.