Fabrication of a superabsorbent and pH-responsive glucomannan-based hydrogel: crosslinking, characterization, toxicological evaluation, and sustained-release of itopride

Abstract

Herein, we describe the esterification of a polysaccharide-based hydrogel extracted from the sweet basil seeds using citric acid (CA). The formation of CA-crosslinked sweet basil seed hydrogel (CL-SBH) was ascertained through FTIR and solid-state CP/MAS ¹³C NMR spectra. SEM analysis showed the existence of microscopic channels in CL-SBH. The CL-SBH was evaluated for its pH- and saline-dependent swelling properties. The highest swelling of CL-SBH was 17.83 g g⁻¹ in DW and the lowest was 4.21 g g⁻¹ at a pH of 1.2 after 480 min (8 h). During the swelling–deswelling studies, the CL-SBH displayed high swelling capacity in DW and in a buffer with a pH of 7.4, whereas the swelling was negligible in ethanol, normal saline, and in a buffer with a pH of 1.2 upon repeated cycles. Tablets based on CL-SBH and a drug (itopride) were prepared, and the results revealed that the itopride release was prolonged for 4 h at pH levels of 6.8 (97.75%) and 7.4 (94.63%), whereas approximately 36.75% of the drug was released at a pH of 1.2. The itopride release pattern followed first-order kinetics along with a Fickian diffusion mechanism. Acute oral and dermal toxicity studies of CL-SBH were conducted on Swiss albino rats and albino rabbits. The CL-SBH appeared non-toxic and non-irritating, as no change in hematological, biochemical, or histopathological parameters was observed in the animal models. Hence, the CL-SBH is a potential non-toxic material synthesized using a green crosslinking agent for prolonged, pH-dependent, and site-specific drug-delivery applications.