Elastomeric closures or rubbers are commonly used for parenterals because of their compressibility and resealability properties. They can be easily penetrated by a hypodermic needle and the puncture reseals after the withdrawal of the needle.

They are impermeable to water vapor and other gases. They reduce the particulate level or extractables in the preparation and are resistant to multiple puncturing, solvents and radiation.

The selection of a rubber closure should be based on buffers used in the preparation, color and pH of product, nature of drug, method of sterilization, concentration of preservative used and nature of vehicle used.