The Development of a Unique Buffered Matrix Aspirin Tablet

Abstract

Aspirin is used widely as an analgetic, antipyretic, and antirheumatic agent. The major disadvantage of aspirin therapy is gastrointestinal irritation caused by direct contact of the solid aspirin crystals and the gastric mucosa which causes gastrointestinal bleeding. Buffered aspirin tablets have been developed to reduce gastrointestinal bleeding. However, these multilayer tablets have proven to be, at times, ineffective.

A compressed buffered aspirin tablet was formulated which was composed of aqueous-based polymer coated aspirin crystals, a buffering system, a hydrophilic gel-forming matrix material, a binder, and a hydrophobic lubricant. The aspirin crystals were coated with an aqueous-based polymer to reduce aspirin degradation caused by the tablet components. The Glatt GPCG5 fluid bed with a top spray apparatus was used to coat 3 to 6 percent wt./wt. polymer onto aspirin crystals.

The coated aspirin crystals were incorporated with the tablet components and directly compressed using conventional tablet technology and equipment. Aspirin was released rapidly from the eroding matrix. Erosion was achieved due to the gel formation of Methocel K100LV which protects the tablet interior from dissolving and disintegrating upon initial wetting and hydration. The buffering system created a microenvironment of pH 5 within and around the eroding tablet matrix to aid in increasing aspirin solubility. The prototype formulation was scaled-up to large processing equipment and tablet stability was evaluated.