RESUMEN
The objective of this investigation was to prepare more stable controlled release aspirin tablets. This was achieved via incorporation of the drug into solid dispersions using three different carries. The carries selected were stearic acid, sodium stearate and magnesium stearate in different ratios. Solid dispersions were prepared by melting technique. The prepared dispersions were evaluated by various methods viz infrared analysis, X-ray diffraction, thermal analysis and microscopic scanning. The previously prepared solid dispersions were utilized to prepare aspirin tablets. It was found that the release from these tablets was dependent on the drug ratio as well as the matrix type. Aspirin release was found to obey first order kinetics. In addition, the drug release was found to be diffusion controlled at 20%, 40% and 60% drug concentration, while solid dispersions containing 80% drug concentration did not follow Higuchi diffusion model