Tamarind seed polysaccharide–gellan mucoadhesive beads for controlled release of metformin HCl

•Ionically-gelled mucoadhesive beads of metformin HCl was developed and optimized.•These beads were made of tamarind seed polysaccharide–gellan gum polymer-blend.•The in vitro drug release showed zero-order with super case-II transport mechanism.•Optimized beads exhibited good mucoadhesivity with the biological mucous membrane.•These beads proved prolonged and significant hypoglycemic effect in diabetic rats. The paper describes the development, optimization and evaluation of tamarind seed polysaccharide (TSP)-blended gellan gum (GG) mucoadhesive beads containing metformin HCl through Ca2+-ion cross-linked ionic gelation for oral drug delivery. Effects of GG to TSP ratio and cross-linker (CaCl2) concentration on the drug encapsulation efficiency (DEE, %), and cumulative drug release after 10h (R10h, %) of TSP–GG mucoadhesive beads containing metformin HCl were optimized by 32 factorial design. The optimized mucoadhesive beads (F-O) showed DEE of 95.73±4.02%, R10h of 61.22±3.44% and mean diameter of 1.70±0.24mm.These beads were characterized by SEM and FTIR analyses. The in vitro drug release from these beads showed controlled-release (zero-order) pattern over a period of 10h.The optimized TSP–GG mucoadhesive beads also exhibited pH-dependent swelling, good mucoadhesivity with biological mucosal membrane and significant hypoglycemic effect in alloxan-induced diabetic rats over prolonged period after oral administration.