Investigation of the Tableting Properties of Modified Dioscorea dumetorum Starch in Direct Compressed Diclofenac Tablet Formulations

Abstract

Background: Modification of starch enhances their performance and improves properties such as compressibility, visco-stability, texture and dissolution. Objectives: The aim of the study was to investigate the direct compression properties of modified starch of Dioscorea dumetorum in diclofenac tablet formulations. Method: Isolated starch from Dioscorea dumetorum tubers was subject to two forms of modification and the modified products characterized with the native starch for their physicochemical and powder properties. The modified starches (5, 7.5 and 10%w/w) and microcrystalline cellulose (MCC) (10%w/w) were used in the formulation of batches of diclofenac potassium tablets via slugging and direct compression. Flowability of granules from their slugs and tablet parameters from their tablet were evaluated using standard procedures. Drug-excipient interaction studies was carried out using FTIR analysis. Results: The extracted starch was white, while the modified forms were off-white in colour. All the starches were smooth in texture and insoluble in water with swelling capacities ≤ 2.85, hydration capacities ≥ 1.22 and moisture contents ≤ 14.5%. Granules gave Carr’s indices, Hausner’s ratios and angles of repose values ranging from 10.71-18.03%, 1.12-1.22 and 20.16- 28.15°, respectively, indicating good flow. Tablet’s friability ranged from 0.01-0.04% while their hardness values was between 4.20-5.50 kp and disintegration times < 7.0 min. Dissolution profiles of the tablets showed over 70% diclofenac release within 45 min. FTIR studies showed no interaction between diclofenac and formulation excipients. Conclusion: Modified Dioscorea dumetorum starch possesses binding and disintegrating properties comparable with MCC, hence it can be used as an alternative to MCC in direct compression of tablets.