Clarifying Critical Care

Lipid-resistant resin provides greater safety in infusion therapy

Infusion systems make it possible for seriously ill patients to receive precisely the medicines and nourishment they need. The materials used to manufacture these systems come into direct contact with blood and intravenous fluid products, and are required to meet strict regulations with respect to biocompatibility, sterilizability, resistance and strength. B. Braun Medical AG, Switzerland, needed to find a material that met these stringent qualifications for making their Discofix range of three-way stopcocks and manifolds.

Working with the Swiss division of Bayer Plastics, researchers from both companies jointly developed Makrolon Rx-1805 lipid-resistant polycarbonate resin, a new grade of Makrolon. “Three-way stopcocks and manifolds are the most highly stressed components of an infusion system. The crucial factor when it comes to choosing the material was the superior stress-crack resistance, as displayed by Makrolon Rx-1805, when in contact with lipid emulsions,” explains Dr. Dirk Möckel, who works in the European marketing section of Bayer’s Plastics Business Group. “The excellent dimensional stability of the resin also ensures that tube connections remain permanently secure.”

The three-way stopcocks are supplied in an individual sterile pack, and can be sterilized with ethylene oxide or gamma rays. Thanks to a special form of stabilization, exposure of the material to gamma radiation causes only slight discoloration that largely disappears with time. The transparency of the polycarbonate makes the medical staff’s work easier by allowing a fast and accurate visual check of the infusion procedure. “This means a higher level of safety for both patients and staff,” said Möckel. Simple, low-cost processing by injection molding is another benefit to Makrolon Rx-1805, giving it a competitive edge over expensive polymers like polysulfones and copolymides. The material complies with the strict requirements of ISO Standard 10993-1 for biocompatibility of plastics that are used in contact with human tissue for 30 days or less.
—SG