Evaluation of the Influence of Pharmaceuticals on the Mechanical Properties of Polymeric Medical Devices

Abstract

Pharmaceuticals reportedly cause damage to some polymeric medical devices that administer them. Because this phenomenon and its causes still remain unclear, in this study, all the possible combinations of polymeric materials and pharmaceutical ingredients that could cause failures were identified by conducting a comprehensive analysis on a wide variety of such combinations and through verification tests using the products. The results of the simple immersion tests and the reports of clinical failures indicated that the failures were not caused by the lack of chemical resistance of the polymers but by the environmental stress cracking (ESC) induced by a combination of the stress generated in the material and the interaction with a specific chemical. Therefore, we evaluated all combinations that could cause ESC by developing and applying a simple method for testing ESC. Polycarbonate and polyethylene terephthalate were found to be damaged by alkaline solutions and oils and fats, and surfactants solutions. These failures were also confirmed by the verification tests. Results from the stress state verification, fractographic analysis, and other studies confirmed that these failures were caused by ESC. Cytotoxicity owing to the induction of ESC was not detected in any combination. These results indicated that the residual stress generated during the manufacturing process was one of the reasons for the failure of the medical devices. This residual stress can be eliminated by employing additional processes such as annealing, thereby preventing medical device failures induced through interactions with pharmaceutical ingredients.