ISO 8362-2: Closures for Injection Vials Explained
ISO 8362-2 is the international standard that specifies the rubber closures (stoppers) used to seal injection vials, defining their shapes, dimensions, and material and performance requirements. It is Part 2 of the ISO 8362 series, “Injection containers and accessories,” and it covers the elastomeric closure that seats in the vial mouth and that a needle pierces to withdraw or deliver the drug. The current edition is ISO 8362-2:2024. It is the standard that lets a vial, its stopper, and its seal from different suppliers fit together reliably.
This guide explains what ISO 8362-2 covers, how it fits within the ISO 8362 series, and how it relates to the pharmacopoeial requirements for elastomeric closures.
Key takeaways
- ISO 8362-2 specifies the rubber closures (stoppers) for injection vials: their forms, dimensions, and requirements.
- It is Part 2 of the ISO 8362 series, “Injection containers and accessories,” which also covers the vials and the caps. The current edition is ISO 8362-2:2024.
- The standard ensures closures are dimensionally compatible with the vials of ISO 8362-1 and the caps of ISO 8362-3, ISO 8362-6, and ISO 8362-7.
- ISO 8362-2 governs dimensions and form; the closure’s material and functional performance are addressed by pharmacopoeial chapters such as USP <381> and USP <382>.
- Special slotted closures for freeze-drying are covered separately by ISO 8362-5.
- Dimensional compatibility across vial, stopper, and seal is what allows reliable crimping and a sound container closure system.
What is ISO 8362-2?
ISO 8362-2 is the part of the ISO 8362 series that defines the rubber closures for injection vials: the elastomeric stoppers that seal the vial and that a needle passes through. It is published by the International Organization for Standardization (ISO), and the current edition is ISO 8362-2:2024, which superseded the earlier 2015 edition.
The closure covered by ISO 8362-2 is the elastomeric closure, the moulded rubber plug (most often a butyl rubber stopper) that seats in the mouth of the vial. ISO 8362-2 standardises the closure’s geometry, the dimensions that must match the vial neck and the cap, and the requirements the closure has to meet. By fixing these forms and dimensions, the standard makes vials, stoppers, and seals from different manufacturers interoperable, which is essential when a drug maker assembles a container closure system from components sourced across suppliers.
What ISO 8362-2 covers
ISO 8362-2 covers the types, shapes, and dimensions of rubber closures for injection vials, together with the requirements those closures must meet. In broad terms it standardises:
- Closure forms and dimensions. The geometry of the stopper, including the plug that enters the vial mouth and the flange that sits on the vial rim, dimensioned so the stopper seats correctly and matches the vial neck and the cap.
- Size designations. Closures sized to the common vial neck diameters (for example 13 mm and 20 mm nominal neck finishes) so they pair with the corresponding vials and caps.
- Requirements and references. Material and performance requirements for the closure, with reference to the relevant test methods and to the pharmacopoeial requirements for elastomeric closures.
The point of the dimensional standard is fit. The stopper has to seat fully in the vial mouth, its flange has to sit correctly under the cap, and the assembly has to crimp cleanly. Dimensions that conform to ISO 8362-2 are what make that reliable across a filling line.
How ISO 8362-2 fits the ISO 8362 series
ISO 8362-2 is one part of a multi-part series that together standardises injection vials and their accessories, so that vials, closures, and caps form a compatible system. Each part addresses a different component.
| Part | Scope |
|---|---|
| ISO 8362-1 | Injection vials made of glass tubing |
| ISO 8362-2 | Closures for injection vials |
| ISO 8362-3 | Aluminium caps for injection vials |
| ISO 8362-5 | Freeze drying closures for injection vials |
| ISO 8362-6 | Caps made of aluminium-plastics combinations |
| ISO 8362-7 | Injection caps of aluminium-plastics combinations without overlapping plastics part |
The closure of Part 2 seats in the vial of Part 1 (or the moulded-glass vial of Part 4) and is held in place by a cap from Part 3, 6, or 7. The freeze-drying closures of Part 5 are a specialised version of the Part 2 closure with slots that let vapour escape during lyophilisation. Because the parts are dimensioned to match, a stopper conforming to ISO 8362-2 will fit vials and caps conforming to the corresponding parts.
ISO 8362-2 and the pharmacopoeial requirements
ISO 8362-2 standardises the closure’s form and dimensions; the pharmacopoeias govern the closure’s material and how it performs in service. The two are complementary, and a closure is qualified against both.
The material requirements of the elastomeric closure (its physicochemical properties) are set out in USP <381>, with parallel requirements in the European Pharmacopoeia for rubber closures for containers for aqueous parenteral preparations. The closure’s functional suitability, such as penetrability, self-sealing, and its contribution to package integrity, is addressed by USP <382>. What can migrate from the rubber into the drug is studied through extractables and leachables work. ISO 8362-2 ties these together at the level of the physical closure: a stopper that is dimensionally correct (ISO 8362-2), made of a qualified material (USP <381>), and functionally suitable (USP <382>) is what completes a reliable closure.
How this works in practice at Autofits
The ISO 8362-2 closure is the rubber stopper; Autofits manufactures the aluminium and aluminium-plastic caps that crimp over it, the components covered by ISO 8362-3, 8362-6, and 8362-7. The range includes FlipTop Optima flip-off seals, tear-off and tear-down aluminium seals, and aluminium pilfer-proof (ROPP) caps, in 13, 20, and 32 mm sizes (see the full products page). Because the cap must crimp over a stopper that seats in the vial, dimensional compatibility across all three components matters: a cap dimensioned to match the vial neck and the seated stopper is what crimps cleanly and holds the seal. Autofits produces its seals under an ISO 15378:2017 quality system, alongside ISO 9001:2015 and ISO 14001:2015 certification and a Drug Master File, in a 75,000 sq ft Nashik facility with an ISO Class 8 cleanroom and high-speed visual inspection for dimensional control. The full certification set is on the quality page.
Frequently asked questions
What does ISO 8362-2 cover?
ISO 8362-2 specifies the rubber closures (stoppers) for injection vials: their forms, dimensions, and the requirements they must meet. It is Part 2 of the ISO 8362 series, “Injection containers and accessories.” By standardising the closure’s geometry and size designations, it ensures the stopper is dimensionally compatible with the vials and the caps covered by the other parts of the series.
What is the current edition of ISO 8362-2?
The current edition is ISO 8362-2:2024, which superseded the 2015 edition. ISO standards are reviewed periodically, so confirm the current edition and its requirements directly with ISO before treating any specific clause as authoritative.
What is the difference between ISO 8362-2 and USP <381>?
ISO 8362-2 standardises the closure’s physical form and dimensions, so vials, stoppers, and caps fit together. USP <381> sets the material (physicochemical) requirements of the elastomeric closure. They are complementary: a stopper should be dimensionally correct per ISO 8362-2 and made of a material that meets USP <381>, with functional suitability under USP <382>.
Does ISO 8362-2 cover freeze-drying stoppers?
The standard rubber closures are covered by ISO 8362-2, but the special slotted closures used for freeze-drying (lyophilisation) are covered separately by ISO 8362-5. Freeze-drying closures have slots or legs that let water vapour escape during drying before the stopper is fully seated, so they have their own part in the series.
How does ISO 8362-2 relate to the aluminium seal?
The ISO 8362-2 closure is the rubber stopper; the aluminium or aluminium-plastic seal crimps over it to hold it against the vial. The seals are covered by ISO 8362-3 (aluminium caps) and ISO 8362-6 and 8362-7 (aluminium-plastic combination caps). Because all the components are dimensioned to match, a closure conforming to ISO 8362-2 pairs with caps conforming to those parts.
Related reading
- ISO 8362-1: injection vials made of glass tubing
- ISO 8362-3: aluminium caps for injection vials
- ISO 8362-6: aluminium-plastic combination caps
- USP <381>: elastomeric components in injectable packaging
- Elastomeric closure: definition
Sources
- ISO: ISO 8362-2:2024, Injection containers and accessories, Part 2: Closures for injection vials (https://www.iso.org/standard/87251.html)
- ISO: ISO 8362-1:2018, Injection containers and accessories, Part 1: Injection vials made of glass tubing (https://www.iso.org/standard/74398.html)
- USP-NF: General Chapter <381>, Elastomeric Components in Injectable Pharmaceutical Product Packaging/Delivery Systems (https://www.usp.org/)
*Last updated: 2026-06-18. This article is general technical information, not regulatory or compliance advice; confirm current standard editions and requirements with ISO and the relevant authorities.*
