Novel pH-sensitive physical hydrogels of carboxymethyl scleroglucan

A carboxymethyl derivative of scleroglucan (Scl-CM) with derivatization degree 300 ± 10 was synthesized and characterized by Fourier transform infrared spectroscopy, potentiometer titration, mucus adhesion studies, and rheological measurements. Rheological measurements showed the ability of the polymer to undergo sol-gel transitions even in the absence of salts. Swelling experiments, performed on freeze-dried samples in different media, showed good affinity of these hydrogels toward the aqueous media and a pH-sensitive behavior. Four nonsteroidal anti-inflammatory drugs (NSAIDs) were loaded into the physical hydrogels obtained from 2.0% (w/v) solutions of the polymer. The results of the release studies carried out in conditions simulating the gastrointestinal tract showed that the new hydrogels could be suggested for the modified oral delivery of NSAIDs, particularly damaging for the gastric mucosa. In vivo studies proved the biocompatibility of the matrix and the absence of any gastric damage for administration of ulcerogenic doses of diclofenac loaded into the hydrogel (DIC/Scl-CM-300). Moreover, DIC/Scl-CM-300 was found to be effective in peripheral analgesia.