Sample Preparation-The samples were prepared by incorporating 12% of aspirin by weight in methoxypolyethylene glycol350, 550, and 5000 and in polyethylene glycol 400. When effects ofwater were studied, a predetermined amount of distilled waterwas added to the bases prior to incorporation of aspirin. Sampleswere kept in airtight containers and stored at 4, 24, 36, and 45