INFLUENCE OF SODIUM ALGINATE AND CARBOPOL ON THE RELEASE PROFILE OF ISONIAZID SUSTAINED RELEASE MATRIX TABLETS: A KINETIC AND MECHANISTIC EVALUATION

Matrix systems remain one of the most popular oral controlled drug delivery technologies owing to their simplicity, cost-effectiveness, ease of manufacturing, and excellent reproducibility. This study sought to investigate the influence of polymer type and concentration on the release behavior of isoniazid from hydrophilic matrix tablets and to elucidate the underlying mechanisms of drug release using kinetic modeling. Sustained release isoniazid tablets were prepared by direct compression using sodium alginate (10 – 40 %w/w) and Carbopol 940 (5 – 20 %w/w) as the matrix-forming polymers. Powder blends were evaluated for some micromeritic properties and loss on drying, while the prepared tablets were assessed for physico-mechanical properties, swelling behavior, and in vitro drug release in 0.1N HCl (pH 1.2). All the formulations exhibited acceptable flow properties, had low moisture content and were within pharmacopoeial specifications for weight uniformity, hardness, friability, and drug content. Sodium alginate-based formulations demonstrated pronounced swelling and sustained drug release over 8 h (≈48 – 62 %), whereas the Carbopol formulations showed minimal swelling and rapid drug release (>80 % within 4 h). Kinetic modeling revealed that drug release from sodium alginate matrices followed the Higuchi model, indicating diffusion-controlled release, with Korsmeyer–Peppas analysis confirming non-Fickian (anomalous) transport. In contrast, Carbopol formulations exhibited Fickian diffusion with significant polymer erosion, resulting in poor sustained-release performance. Overall, sodium alginate proved to be a more effective matrix-forming polymer than Carbopol for sustained delivery of isoniazid due to its gel-forming and diffusion-modulating properties.