Safety Concern - Latex in Rubber Stoppers
ALK rubber stoppers are made of gray butyl synthetic rubber, but contain a small percentage of natural rubber, which may theoretically contain latex allergens that could interfere with proper diagnosis in latex- sensitive patients.
n research that evaluated the potential effect of latex in rubber stoppers on allergenic extracts, it was shown that under routine use conditions, there was no evidence of latex allergen seeping into the extract. The two stoppers used in the study which contained latex were either pure natural rubber or 66% natural rubber whereas the rubber stoppers ALK purchases are well below this level at 13.9% natural rubber.
Due to the harsh manufacturing processes used in rubber stopper production, it is unlikely that allergenic proteins from natural rubber will be present in rubber stoppers, much less cause a problem. Even if there could be an issue with proper diagnosis, the use of a negative diluent control would identify reactivity to components in the stopper or the diluent. Even among highly allergic patients, reactions to negative controls are rare occurrences and are typically due to Dermographism (a condition, found in 4-5% of the population, where the skin releases histamine upon contact, thus confounding skin test results).
While latex allergy is a serious topic, in the many thousands of vials that have been used over the years we have not heard of a single case where a latex allergic patient had a latex reaction to an allergen extract.
While it may be theoretically ideal to have latex-free rubber stoppers, we have not seen evidence that this is necessary or even ideal, as synthetic rubber may be more brittle than natural rubber and be more prone to coring, which is a much more common problem.
Currently there is no latex allergen extract.