The construction and uses of factorial designs in the preparation of solid dosage forms. Part 1: Effervescent acetylsalicylic acid tablets.

The construction and application of a fractional factorial design of the type N = 2(5-2) for the preparation of effervescent acetylsalicylic acid tablets by a new technique was demonstrated. This method involved direct compression of the tablet ingredients, dipping the tablets in a volatile mixed solvent system and subsequent removal of the solvent. With the help of a derived regression equation, the factors considered most likely to have a beneficial effect on tablet hardness were: the compression force, the percent of acetylsalicylic acid content/tablet, the particle size of tablet ingredients and the solvent ratio. The time of dipping was found to have an insignificant effect on tablet hardness. By following the path of the steepest ascent, effervescent acetylsalicylic acid tablets of remarkable hardness, friability and dissolution time were obtained. The optimum conditions for preparing these tablets were determined.