Abstract: 
Sustained release diclofenac sodium matrix tablets (~100 mg) were prepared by wet granulation using blends of cashew gum, xanthan gum and HPMC as drug release modifiers. The flow properties of diclofenac sodium granules and the physical properties of the compressed matrix tablets namely, weight variation, tablet thickness, crushing strength, friability, drug content and swelling index were evaluated. In vitro dissolution studies were performed in phosphate buffer (pH 7.5) using Voltaren Retard® tablet as a reference drug. Kinetic models and difference (f₁) and similarity (f₂) factors were employed to evaluate the drug release data. The granules exhibited good flow properties while the physical properties of tablets generally fell within acceptable limits. Tablet formulations containing 60-100 % xanthan gum exhibited high water absorption capacities in phosphate buffer pH 7.5. Formulations F10, F12, F13 and F15 passed the dissolution test for modified release oral tablets while the rest failed the test. Formulations F7 to F15 appeared similar to the reference drug (p < 0.05; f₁ ≤ 10; f₂ ≥ 60) and could be used interchangeably. Drug release data fitted well to the Higuchi square root model and the Korsmeyer-Peppas equation, indicating anomalous or non-Fickian drug release. Blends of cashew gum, xanthan gum and HPMC when employed in the appropriate ratios could optimize the sustained release activity of diclofenac sodium matrix tablets.

Keywords: Natural Gums, Hydrophilic Polymers, Swelling Capacity, In Vitro Dissolution, Sustained Release.