Computer optimization of the formulation of acrylic plaster

A computer optimization technique was applied to obtain the optimum formula of acrylic plaster vehicle containing ketoprofen (KPF). The dissolution rate of KPF, in vivo percutaneous absorption of KPF, stability of the dissolution behavior of KPF and adhesiveness of the plaster were determined as characteristics for deciding the formula of an optimum plaster vehicle. The amounts of 2-ethylhexyl acrylate (X_1), vinyl acetate (X_2) and 2-hydroxyethyl acrylate (X_3) were selected as factors (independent variables). The plaster characteristics were predicted by the secondorder polynominal regression equation involving these factors. The physical meaning of the regression equation for each characteristic was defined by the application of contour graphs. A mixture of 65 g of X_1,60 g of X_2 and 1.38 g of X_3 was predicted to be the optimum for the plaster vehicle.