Formulation of enteric granules containing green tea (Camellia Sinensis) extract using eudragit l100-55 as a delayed release matrix

Objective: Epigallocatechin gallate (EGCG) inhibits glucose absorption into the blood by inhibiting small intestinal a-glucosidase but is unstable in gastric fluid. Hence, we formulated EGCG into enteric preparations that prevent release in gastric fluid. Methods: Granules were prepared using a wet granulation method and were formulated into polyvinylpyrrolidone (PVP)-Eudragit L100-55 (5:1; F1), PVP-Eudragit L100-55 (1:1; F2), and Eudragit L100-55 (F3) preparations using 30% w/w Eudragit L100-55 as a matrix. EGCG contents of granules were evaluated and dissolution tests were performed at pH 1.2 and 6.8. Results: F1-3 formulas had good flow properties and contained EGCG at 24.05%±0.15%-24.96%±0.28%. Dissolution tests showed that F1 and F2 formulas released EGCG at 50.53%±0.04% and 17.80%±0.55%, respectively, after 2 h in HCl medium at pH 1.2. Cumulative drug release from F1 and F2 formulations after 2 h under these conditions (pH 1.2) and 1 h in phosphate buffer (pH 6.8) was 94.40%±1.58% and 93.70%±1.08%, respectively. Conclusion: As the optimal formula, F3 granules limited drug release to 7.03%±0.22% in HCl at pH 1.2 over 2 h and cumulative drug release in HCl medium (pH 1.2) followed by phosphate buffer (pH 6.8) of 86.13%±0.20%.