Evaluation of starch-clay composites as a pharmaceutical excipient in tramadol tablet formulations.

Background: Co-processing starch with clay nanocomposite has been shown to yield a new class of materials, potentially with better properties than pristine starch, that could be used as directly compressible excipients in tablet formulations.

Objectives: In this study, starches from 3 botanical sources, i.e., millet starch from Pennistum glaucum (L) RBr grains, sorghum starch from Sorghum bicolor L. Moench grains and cocoyam starch from Colocasia esculenta L. Schott tubers, were co-processed with montmorillonite clay (MMT) and evaluated as a directly compressible excipient in tramadol tablet formulations. The effects of different starch-to-clay ratios on the material and drug release properties of the resulting tablets were evaluated.

Material and methods: The starch-clay composites were prepared by heating a dispersion of the starch in distilled water, then precipitating the dispersion with an equal volume of 95% ethanol. The starch-clay composites were characterized and used as direct compression excipients for the preparation of tramadol tablets. The mechanical and drug release properties of the tablets were evaluated.

Results: Co-processing MMT with the starches yielded starch-clay composites with different material and tablet properties than the pristine starches. The co-processed starch-MMT biocomposites exhibited improved flowability and compressibility over the pristine starches. The mechanical and drug release properties of tramadol tablets containing starch-clay composites were significantly better than those containing only pristine starches. The properties of the starch-clay composites were not related to the botanical source of the starches.

Conclusions: The study showed that starch-clay biocomposites could be used in the controlled release of tramadol.