NATURAL POLYMER-BASED SUSTAINED-RELEASE TABLETS OF ATENOLOL: ADVANCES IN MATRIX DESIGN, DRUG-RELEASE KINETICS, AND FORMULATION OPTIMIZATION

Atenolol is a hydrophilic, β1-selective adrenoceptor antagonist that remains widely prescribed for hypertension, angina and arrhythmia, yet its elimination half-life of 6–7 h, incomplete oral absorption (about 50%) and dependence on dosing regularity make it a logical candidate for sustained-release delivery. Natural polymers such as plant gums, mucilages, polysaccharides and chitosan are attractive matrix formers because they are inexpensive, biodegradable and locally available. This review covers the biopharmaceutical profile of atenolol, the properties of the main natural polymers, the hydration, swelling, diffusion and erosion processes that govern release, formulation and evaluation strategies, and the kinetic models applied to dissolution data. Published atenolol studies are compared with a nine-formulation direct-compression series built on Aegle marmelos gum, tamarind seed gum and chitosan, in which the Aegle marmelos formulation FB1 released 90.01% of drug over 810 min while chitosan formulations followed near zero-order kinetics. Refitting the same dataset shows that the 'best' kinetic model depends heavily on the fitting window and the statistic used, which argues for more rigorous model comparison in this literature. Source variability, moisture sensitivity, weak standardisation and the scarcity of in vivo data remain the main obstacles, and practical solutions are discussed.