CINCINNATI (Oct. 9, 2012)—Kraton Performance Polymers Inc. said a study on elastomers used in medical stoppers showed that one of its materials performed best in the strictest protocol.
The results were presented in a paper, “Improved medical stopper solutions with high-performance, anionic isoprene rubber,” given at the ACS Rubber Division's International Rubber Expo by Philippe Henderson, Kraton's global industry business manager for Cariflex-brand polyisoprene products.
The study was performed by a third party and compared the chemistry and performance of four rubber families currently used in medical stoppers: anionic polyisoprene; Ziegler-Natta IR; chorobutyl rubber; and bromobutyl rubber.
It showed that the medical stoppers made with the Cariflex IR products—an anionic IR made by Kraton—easily passed the extraction test under Japanese Pharmacopeia 7-03 (XV revision 2006), the most stringent protocol, according to the company. Kraton said the Ziegler-Natta IR failed or only marginally passed the test.
Henderson said the study shows that the anionic isoprene rubber provides several advantages, including the absence of natural rubber proteins present in NR, an odor-free formulation with low residual metals and no residual catalysts, low needle insertion force, and minimal risk of rubber fragmentation and medication contamination caused by needle insertion.
He said the chlorobutyl and bromobutyl rubbers did pass the test as well, and those materials also provide an oxygen barrier. But he said the Carilex IR rubber can be used when an oxygen barrier isn't needed, noting that there are other ways to provide the barrier, such as putting an aluminum cap on the product.