Evaluation of Native and Cross-Linked <i>Acacia Senegal</i> Gums as Sustained Release Agents in Tablet Formulations

Abstract

Acacia senegal var. senegal and Acacia senegal var. karensis gums were modified using microwave irradiation and subsequently evaluated for their sustained release effects in pharmaceutical tablet formulations. Microwave-induced cross-linking resulted in cross linked gum to the extent of 34.95% and 27.39% for var. senegal (AH) and var. karensis (AS), respectively, at different irradiation powers and reaction times. Fourier transform infrared spectroscopy (FTIR) studies indicated the compatibility of the gums with the model drug, theophylline. Dissolution studies showed AS, Cross-linked var. karensis (CAS) and var. senegal (CAH) can sustain the release of the drug beyond 12 h at higher gum concentrations (p < 0.05) indicating the drug retarding ability of the gums. Higher drug release was obtained when var. senegal was used as matrix former, while the rest showed slower release rate (p < 0.05). Cumulative drug release was slower from the matrix tablets made by wet granulation compared to tablets prepared by direct compression (p < 0.05). Among 24 formulations, three were found to have comparable release profiles with that of the commercial theophylline sustained release matrix tablet (Pliva-482^®). Theophylline release predominately followed first order kinetics and the mechanism was found to be diffusion coupled with erosion. Hence, native and cross-linked var. karensis and cross-linked var. senegal gums can be utilized as sustained release excipients.

Keywords: acacia gums, cross-linking, microwave irradiation, sustained release, theophylline