Hydroxypropylation of starch enhances its potential applications, especially its use in specialized drug delivery systems. The study aimed at exploring the sustained release property of hydroxypropylated (HP) cassava and potato starches in diclofenac sodium tablet formulations. Native cassava and potato starches were hydroxypropylated and used in the preparation of batches of diclofenac powder blends and granules either as powders (filler) or mucilage (binder). Powder blends/granules flow properties were investigated as well as drug-excipient interaction using Fourier transform infra-red spectroscopy prior to tablet compression. Compressed tablets were evaluated for tablet properties and in vitro drug release was compared with a commercial brand. Drug release kinetics and mechanisms of the tablets were determined from the dissolution profiles. Powder blends and granules containing HP starches exhibited excellent flow properties. Drug-excipient studies showed the absence of any interaction. Formulated tablets had uniform weights with concentration-dependent hardness for those prepared with HP starch mucilage and were stronger than those prepared with HP starch powder via direct compression. Tablets incorporated with HP starch mucilage produced non-friable tablets (≤ 1%) while those prepared with powder blends were highly friable (10.00 and 11.39 %). Drug release from the tablets was sustained ranging from 43.60 – 81.67% within 8 h and comparable with that of the commercial brand (44.38%). Kinetics of drug release followed first-order with Hixson-Crowell mechanism of release while the commercial brand favoured zero-order kinetics. The study showed that hydroxypropylated cassava and potato starches have potential to retard the rate of drug release in tablet formulations.
