Preparation, characterization, in vitro and in vivo evaluation of PEGylated-mucin matrix tablets containing aqueous leaf extract of Vernonia amygdalina

The objectives of this research were to formulate and evaluate PEGylated mucin matrix tablets containing Vernonia amygdalina leaf water extract. PEGylated mucin matrices formulated with PEG 8000 and mucin from the African land snail Archachatina marginata at ratios 1:1, 0:1, 1:0, 3:1 and 1:3 were used to prepare V. amygdalina tablets by dry granulation and direct compression. Characterization based on surface morphology, weight uniformity, friability, hardness/crushing strength and absolute drug content were carried out on the tablets. The in vitro release studies were performed in phosphate buffer saline (PBS, pH 7.4), while the in vivo release studies were conducted using alloxan-induced diabetic rats. The results obtained showed that the tablets were smooth and circular in shape, maintained a percentage deviation of 3 to 5% in the weight uniformity test, had percentage average resistances (friability) less than 1% and crushing strengths less than 5 kgf, and thus conformed to compendial requirements for acceptance. In vitro release studies indicated sustained release potentials of the tablet formulations. Further kinetic analysis of drug release showed predominance of the Higuchi square root model and Fickian diffusion release mechanism. In vivo antidiabetic study revealed mucin-dependent glucose lowering potentials of the tablets which were significantly (p < 0.05) greater than those of commercial glibenclamide tablets. The method of prepartion of PEGylated mucin tablets needs to be carefully selected to ensure the production of tablets with adequate bond strength to withstand the rigours of handling and at the same time release the active compound(s) for biological action. Key words: Vernonia amygdalina, PEGylated-mucin, hyperglycaemic, tablet.