Core–Shell Structured Low-Methoxyl Pectin-Fenugreek Galactomannan Carboxymethyl Ether-Nanosilica Based Gastroretentive Composites as Glimipride-Carriers

The present investigation aimed at developing core–shell type low-methoxyl pectin (LMP)-fenugreek galactomannan carboxymethyl ether (FGCE)-nanosilica (NS) based composites for intragastric glimipride (GLI) delivery by combined bioadhesion-floating approache. Initially, FGCE (degree of carboxymethylation, 0.71) was synthesized and characterized by FTIR, XRD and DSC analyses. LMP-FGCE-NS core matrices loaded with GLI were then afforded by ionic gelation protocol utilizing zinc acetate as a cross-linking agent. The core composites were subsequently coated by LMP-sodium alginate (SA) based gel membrane exploiting interfacial complexation technique. Various matrices substantiated excellent drug encapsulation efficiency (DEE, 46–83%) and delayed drug eluting profiles (Q_8h, 57–76%). These attributes were enormously influenced by different formulation variables such as polymer-blend (LMP: FGCE) ratios, NS types and LMP-SA coating incorporation. The GLI release characteristics of the core–shell composites (F-7) obeyed zero-order kinetic model and fitted to anomalous transport driven mechanism. The formulations also depicted their excellent gastroretention ability and biodegradability. The molar mass ($\overline{M}$c) between the crosslinks of composites (F-7) estimated using Flory–Rehner equation was declined with temperature. Furthermore, the composites were examined for drug-excipients compatibility, alteration of thermal behavior, transformation of drug crystallinity and surface morphology. Thus, the newly engineered composites are apposite for stomach-specific controlled GLI delivery for type 2-diabetes management.