The construction and uses of factorial designs in the preparation of solid dosage forms

The present experiments were factorially designed to study the effect of particle size (X3), at different levels of both temperature (X1) and time (X2), on the hardness and mechanical strength of sintered tablets. A 2 X 2 X 3 design was constructed for salicylamide tablets with X1, X2 and X3 at 2,2 and 3 levels respectively. For phenobarbital tablets, a 3 X 3 X 3 factorial experiment was run. On the basis of analysis of variance, empirical regression equations have been developed. Within the limits of the factors, it was found that the quadratic effect of X 2/3, on the average, was the most significant. The significance of the linear effects was in the following order: X3 greater than X1 greater than X2 in salicylamide tablets and X1 greater than X3 greater than X2 in phenobarbital tablets. A change of X3 from the high to the low or intermediate levels caused an increase in the mechanical properties of tablets. The only linear interaction was that of X1X3 for the hardness data of phenobarbital tablets, but it was of least significance among the other effects. Other quadratic main effects of X 2/1, X 2/2 and quadratic interaction effects of X 2/3X1 and X 2/1X2 were also found to be significant. The optimum values of the factors studied, that would maximize any given mechanical property, were located.