Rubber closures for containers for aqueous parenteral preparations, for powders and for freeze-dried powders are made from elastomers obtained by vulcanisation (cross-linking) of macromolecular organic substances, using appropriate additives. They include stoppers for vials, sealing disks and plunger stoppers for cartridges, as well as rubber tip caps, needle shields and plunger stoppers for syringes, etc. The elastomers used in the manufacture of rubber closures are either synthetically produced or natural-origin polymers. The use of natural rubber latex, which is known to cause allergies, is not permitted, but dry natural rubber may be used since the allergens are removed during processing. The choice of the principal components and of the various additives (vulcanisers, accelerators, stabilisers, pigments, etc.) depends on the target properties of the final article. The specifications in this general chapter apply to rubber closures made from one kind of rubber only, and also to coated closures and bi-layer seals. Coated closures consist of a bulk of rubber, bearing on its surface or part of its surface a layer of a different polymer. Bi-layer seals are composed of 0 different layers of rubber: one layer exhibits a higher level of chemical purity and is intended for contact with the pharmaceutical preparation, and the other layer presents greater elasticity and is intended to improve self-sealing and fragmentation resistance of the seal. Rubber closures are typically treated with silicone oil (0.0.0) or other lubricants, including materials chemically or mechanically bonded to the closures.

Lubricated closures comply, in their lubricated state, with the requirements defined in this general chapter. This chapter does not cover closures made from silicone elastomer. Requirements for silicone elastomer used for the manufacture of closures are dealt with in general chapter 0.0.0. Silicone elastomer for closures and tubing.