Bupivacaine-loaded chitosan hydrogels for topical anesthesia in dentistry

Abstract

The paper describes the preparation of polymeric hydrogels, loaded with bupivacaine, which could represent a good alternative in clinical dentistry as local anesthetics. The hydrogels were prepared by condensation using an amidation reaction between a natural polymer (chitosan) and a synthetic one, poly[(maleic anhydride)-alt-(vinyl acetate)]. Infrared spectroscopy studies confirmed crosslinking through the presence of amide bonds, formed between the two types of polymer chains. Scanning electron microscopy results demonstrated that the hydrogels have a porous structure, the pore dimensions being non-uniform with diameters between 200 and 600 μm. Hydrogels presented good bupivacaine inclusion and release capacity whereas theoretical analysis confirmed the validity of the generalized fractal model, reinforcing a csavi-universal pattern of drug release. Cytotoxicity tests on human dermal fibroblasts revealed that the obtained hydrogels are not cytotoxic. In vivo, the bupivacaine-loaded hydrogels presented anesthetic effects after 15 min and no side effects were observed. This system has the advantage of alleviating or eliminating pain associated with invasive procedures and avoiding direct contact of the drug with tissues, leading thus to the prevention of side effects. © 2020 Society of Chemical Industry