Pectin–gelatin and alginate–gelatin complex coacervation for controlled drug delivery: Influence of anionic polysaccharides and drugs being encapsulated on physicochemical properties of microcapsules

Microencapsulations using pectin and alginate by complex coacervation with gelatin were studied using metronidazole hydrochloride (MH), diclofenac sodium (DS) and indomethacin (IM) as core material. MH was poorly encapsulated (4–7% w/w) than DS (49–53% w/w) and IM (62–66% w/w). Pectin produced coacervation with gelatin with all acidifiers but alginate produced coacervation only with acetic acid. Addition of sodium carboxymethyl cellulose reduced aggregation between the microparticles. FT-IR confirmed the complexation between pectin or alginate with gelatin and intact nature of encapsulated drug. Microencapsulation of MH produced microspheres and DS/IM resulted in irregular particles. Alginate–gelatin produced smaller microparticles than pectin–gelatin. DSC of microcapsules revealed change in physical nature of DS whereas IM produced no changes. The microcapsules showed low drug release in gastric fluid and sustained release in intestinal fluid. Alginate was better than pectin for coacervation with gelatin in terms of less aggregation, smaller particle size and easy dispersion.