Interactions between polymeric containers and their contained solution: Modeling of polymer‐water solute partitioning via coupled solvent‐water partition coefficients

Abstract

AbstractThe interaction between several polymeric materials, typical of those that have application as parenteral product containers, and 16 marker solutes was evaluated. Polymers used included polypropylene, polyvinyl chloride, ethylenevinyl acetate, an olefin rubber, a polyester ether block copolymer, and various composites of these materials. In addition, the partitioning of solutes between two common PVC plasticizers (dioctyl phthalate and butyryl hexyl citrate) and water was also examined. Correlation between equilibrium interaction constants (Eb) (which describe the equilibrium distribution of a solute between contacting polymer and solution phases) and solute octanol‐water (Po‐w) or hexane‐water (Ph‐w) partition coefficients were in general poor for all materials studied. However, a bivariate linear interaction model relating Eb to both partition coefficients: effectively mimicked the interaction behavior of all materials evaluated. The utilization of the developed models to facilitate container compatability assessments is discussed. In addition, the use of a critical ratio of binding constants for a pair of solutes is introduced as a means of qualitatively assessing the effectiveness of a particular solvent as a polymer model.