Formulation and Evaluation of Matrix Tablet of Indomethacin Using Natural Polysaccharide

Abstract

Indomethacin, a potent non‑steroidal anti‑inflammatory drug, requires repeated dosing with conventional oral formulations, leading to fluctuations in drug exposure. Sustained‑release matrix tablets provide a simple approach to prolong drug release and improve dosing convenience. The present study aimed to formulate and evaluate sustained‑release indomethacin tablets using guar gum, a natural polysaccharide matrix‑forming polymer, in combination with Eudragit S100, a pH‑dependent release‑modifying polymer.

Three formulations (F1–F3) containing 25 mg indomethacin per tablet were prepared by direct compression, with guar gum concentrations of 100, 110, and 120 mg, respectively. Eudragit S100 was adjusted to maintain a constant tablet weight of 250 mg, while lactose, talc, and magnesium stearate served as excipients. Powder blends were assessed for flow properties, and tablets were evaluated for weight variation, thickness, hardness, friability, drug content, and swelling behavior. In‑vitro dissolution was performed under sequential acidic and intestinal conditions, and release data were fitted to kinetic models.

All formulations exhibited satisfactory flow, compression, and physical properties. Increasing guar gum concentration enhanced swelling and reduced drug‑release rate. The optimized F3 formulation (120 mg guar gum, 69.5 mg Eudragit S100) showed a swelling index of 204.6%, acceptable mechanical strength, and 94.1% cumulative drug release over 16 h. Release kinetics best fit the Korsmeyer–Peppas model (R² ≈ 0.995), with an exponent of 0.72, indicating anomalous/non‑Fickian transport involving diffusion and polymer relaxation.

The findings demonstrate that guar gum effectively controls indomethacin release, while Eudragit S100 provides pH‑dependent modulation. The developed matrix system offers a promising sustained‑release strategy for indomethacin.