Influence of water-soluble polymers on the in vitro performance of floating mucoadhesive tablets containing metformin

Abstract

Context: The in vitro performance of floating mucoadhesive metformin tablets was optimized using different polymer ratios of polyvinylpyrrolidone (PVP) tamarind seed gum (TSG) and hydroxypropylmethylcellulose (HPMC).Objective: The objectives of this investigation were to investigate the combinatorial effects of PVP, TSG and HPMC; to study the work of adhesion measured on stainless steel (Wss) and on rabbit gastric mucosa (Wgm); and a comparison of hydrophilic and more hydrophobic tablets.Material and methods: In vitro performance was measured as tablet hardness (H), tablet floating lag time (FLT), time needed to release 60% of drug content (t60%), swelling thickness (S), Wss and Wgm. To compare the effects, a simplex lattice mixture design was used.Results and discussion: H, FLT, Wss and Wgm were found dependent on polymer ratio. H was increased when PVP ratio was increased. FLT, Wss and Wgm were increased when HPMC ratio was increased. The p value for the lack of fit for all models were greater than 0.05. An approximate linear correlation between Wgm and Wss was established (R2 = 0.71). The tablets containing PVP resulted in larger H, shorter FLT and t60%, whereas Wss and Wgm were enhanced.Conclusion: The different in vitro performance of tablets containing different water-soluble polymers could be explained partially by the differences in the hydrophilic properties of the polymers and the ability of PVP to interact with HPMC or TSG. An equation established is used to conclude mucoadhesion based on adhesion measurements on stainless steel.