ARRACACIA XANTHORRHIZA ACETYLATED STARCH: A NEW EXCIPIENT FOR CONTROLLED DRUG DELIVERY

Abstract

Objective : Chemically modify by acetylation, Arracacia xanthorrhiza starch, and to physicochemically and pharmacotechnically characterize it, thereby evaluating its potential as a pharmaceutical excipient, in comparison with the native starch of Arracacia xanthorrhiza. Methods : The chemical modification was performed through acetylation with acetic anhydride (AA) on different levels, determining following starch’s characteristics: degree of substitution (DS), size and form of particles, its degree of crystallinity through X-ray powder diffraction (XRPD), gelatinization temperature (Tg) through differential scanning calorimetry (DSC), swelling power (SP) and sorption isotherms by means of Enslin method, and its application as excipient in tablet production, using diclofenac as model drug. Results : On the third level of substitution, the morphology of modified-starch particles presented changes on their surface and all modified starches increased their particle average sizes, in comparison to native starch. Starch crystallinity was not altered by acetylation, and the DS increased as more AA was added to the reaction. This modification caused a decrease of Tg by approx. 9.45 °C for A. xanthorrhiza starch modified to level III, in comparison to native starch. SP and water uptake capacity increased with starch modification, being greater to higher DS. Dissolution studies conducted on tablets showed that diclofenac delivery occurs practically immediately when using native starch, while those made of acetylated starch were close-fitting with Korsmeyer-Peppas model, with a release mechanism that suggests an anomalous, non-Fickian transport behaviour, related to a mechanism governed by swelling and diffusion. Conclusion : The results suggest A. xanthorrhiza acetylated starches, as promising materials for the development of controlled-delivery matrix systems.