Ispaghula husk-based extended release tablets of diclofenac sodium: formulation, evaluation and in vitro release studies

Purpose: To formulate extended-release tablets of diclofenac sodium based on ispaghula husk Methods: Tablets with varying proportions of diclofenac sodium and ispaghula husk were formulated by wet granulation technique at a fixed compression force of 10 kN. The formulated tablets were evaluated for physicochemical parameters as well as by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and x-ray diffraction (XRD). Results: Content uniformity, weight variation, thickness and friability of the formulated tablets were within acceptable limits. The hardness of the tablet decreased from 5.4 to 4.2 kg/cm2 with increasing quantity of ispaghula husk in the formulation. In contrast, disintegration time increased from 12 to 70 min with increasing amount of husk. Tablets formulated with 1:0.25 and 1:0.5 drug/husk ratio failed to extend drug release whereas tablets prepared with 1:0.75 and 1:1 ratio extended release up to 5 and 6 h, respectively. FTIR, DSC and XRD analysis of tablets revealed the absence of diclofenac-ispaghula interaction and crystalline nature of diclofenac sodium. Drug release data fitted well with KorsmeyarPeppas and the n value of 0.98 indicate non-Fickian diffusion. The tablets were stable on storage and retained its physicochemical properties within acceptable limits. Conclusion: The results indicate the possibility of formulating extended-release tablets based on ispaghula husk. The tablets were stable during storage and free from drug-excipient interactions. However further studies are required to ascertain the safety of the husk and to optimize the release properties of the tablets.