Compaction Properties of Acrylic Resin Polymers with Plastic and Brittle Drugs

Abstract

Tensile strengths of compacts consisting of acrylic resin polymers in combination with a plastic drug (theophylline) and a brittle drug (sodium sulfathiazole) were investigated. The polymers studied included Eudragit RS PM, RL PM, S 100, L 100, and L 100-55. All compacts were compressed to a solid fraction of 0.81. The solid fraction, rather than compression force, was kept constant in order to account for the differences in packing characteristics and elastic and plastic deformational properties of different materials (1). Tensile strength profiles for the blends of the Eudragit S 100 and RL PM polymers with sodium sulfathiazole included approximately linear relationships between pure drug and pure polymer. The Eudragit L 100-55 exhibited a large peak in the tensile strength of compacts containing 20% sodium sulfathiazole. Significant differences between the physical-mechanical properties of the methacrylate ester and methacrylic acid copolymers were observed where the latter proved to be much stronger at all concentrations. The differences between the two categories of polymers were greater in compacts containing the plastic drug, theophylline. Peaks in tensile strengths were seen for both drugs with all three of the methacrylic acid copolymers, while the methacrylate ester copolymers maintained approximately linear relationships for all ratios of drug and polymer.