After packaging, a selection of bags should be examined for tears as a part of the quality control assessment. The placement
of the stoppers into the packaging should be undertaken within an ISO Class 8/EU GMP Grade C cleanroom for standard stoppers
and in an ISO Class 5/EU GMP Grade A environment for ready-to-sterilize or ready-to-use stoppers.
Closures are typically sterilized by one of two methods: steam sterilization using autoclaves and gamma irradiation. It should
be noted that not all types of stoppers can be sterilized by gamma irradiation because the rubber of the stopper will become
brittle from the generation of free radicals in the polymeric materials (11).
The sterilization of stoppers also requires the sterilization device to be subject to the standard tests including thermometric
studies and biological indicators for steam sterilization devices and dosimeters for gamma irradiation.
The container-closure system is an essential part of the final presentation of a pharmaceutical product. It defines the closure,
protection, and functionality of a container while ensuring the safety and quality of the drug product over the product shelf
life. This article has addressed the important considerations for closures: the "rubber" stoppers inserted into vials of products
and sealed in place. The article has focused upon the important tests, control measures, and essential aspects for ensuring
that the product, in its final packaging, is fit-for-purpose prior to the administration of the drug.
Tim Sandle, PhD, Bio Products Laboratory, Dagger Lane, Elstree, WD6 3BX, United Kingdom, firstname.lastname@example.org