USP <381> - Elastomeric Closures for Injections

What it says

General Chapter <381> describes physicochemical and biological testing requirements for elastomeric closures, such as rubber stoppers, used with injectable products, addressing extractable substances, fragmentation resistance, and self-sealing capacity for closures intended for multiple needle penetrations.

Paraphrased for plain-language clarity. Always verify against the current published regulation text.

What it means in practice

• Elastomeric closures are a specific, critical container-closure component for injectable products, connecting directly to the broader container-closure integrity and compatibility principles described under 21 CFR 211.94, but with testing requirements specific to elastomeric material characteristics.
• Fragmentation resistance testing addresses a genuine, specific patient safety risk, the possibility that needle penetration through a stopper could shed rubber particulate into the injectable product, a risk with no direct parallel for solid oral dosage form packaging.
• Self-sealing capacity testing is specifically relevant for multi-dose vial closures, where the same stopper must maintain container closure integrity across multiple needle penetrations over the product's in-use period.

What inspectors look for

• Whether elastomeric closure qualification includes fragmentation and self-sealing testing appropriate to the specific product's intended use, single-dose versus multi-dose.
• Whether extractables testing for the specific elastomeric closure formulation used has been performed and connects to the broader extractables and leachables assessment for the product.
• Whether closure supplier changes trigger reassessment of these specific physicochemical and biological performance characteristics, not just visual or dimensional confirmation.

Related regulations