Combination Cap Injectable Biologics
13 / 20mm both size
4-layer composite closure
aqueous compatible *
self-sealing post-puncture
multi-dose, vial compatible
USP / Ep / ISO compliant
- Fast Delievery
- Quality Assurance
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Full Customization
Description
Combination Cap · Aqueous Injection · 13mm / 20mm
Flip Off Seal · Butyl Stopper · USP · EP · ISO 8362
combination cap for aqueous injection · flip off seal · IV injectable vial closure · 13mm 20mm
Combination Cap
for Aqueous Injection
13mm & 20mm · 4-Layer Composite Flip Off Seal · Medical Butyl Stopper · IV · IM · Multi-Dose
Hermetic seal · easy needle penetration · self-sealing · sterilization-resistant · USP / EP / ISO 8362
|
13mm / 20mm Both sizes |
4-layer Composite closure |
Aqueous Compatible ★ |
Self-sealing Post-puncture |
Multi-dose Vial compatible |
USP/EP/ISO Compliant |
What is a combination cap - aqueous injection context
The combination cap - engineered specifically for aqueous injectable vials
A combination cap for aqueous injection is a composite primary closure that integrates the vial's tamper-evident overcap and primary rubber seal into a single pre-assembled unit. Its 4-layer construction is designed to meet the specific demands of aqueous pharmaceutical formulations: maintaining sterility through autoclave sterilisation, resisting the aqueous environment over the product's shelf life, and allowing reliable needle access under clinical conditions.
layer 1
PP flip tab - tamper evidence
Visible outer element · colour-coded
Removed by healthcare worker before needle insertion. Its presence confirms the vial has not been previously accessed. Colour-coded to identify product, dosage, or department.
layer 2
Aluminium crimp shell - structural hold
Crimp-formed · continuous seal force
Crimp-formed over the vial neck after filling and stoppering. Holds the butyl stopper under continuous compression against the glass neck through all temperature cycles from autoclave sterilisation to refrigerated or ambient storage.
layer 3
PP inner liner - stopper protection
Alignment · force distribution · clean surface
Sits between the aluminium shell and the rubber stopper - protecting the needle-penetration surface from direct metal contact during crimping and autoclave, and distributing the crimp force evenly across the stopper head.
layer 4
Medical butyl stopper - primary seal
Hermetic seal · self-sealing · aqueous compatible
The primary hermetic seal. Bromobutyl or chlorobutyl rubber, tested to USP <381> and EP 3.2.9 for aqueous injectable use. Allows needle penetration, then self-seals after withdrawal to maintain sterility for the full multi-dose vial.
Why "combination cap" - the term explained
The term "combination cap" reflects the fact that this closure is a factory-assembled combination of components rather than separately applied parts. In a traditional closure process, a rubber stopper is pressed in first, then a separate aluminium cap is crimped over it. A combination cap arrives pre-assembled - stopper already seated in the cap shell - so the manufacturer applies a single component in one operation. This simplifies the capping line and improves closure consistency, particularly for high-speed aseptic filling of aqueous injectable vials.
Aqueous compatibility - why butyl rubber is the standard choice
Aqueous injectable formulations - why the butyl stopper is the right choice
The aqueous injection environment places specific demands on the rubber stopper component of the combination cap. Not all elastomers perform equally well in contact with aqueous pharmaceutical formulations - butyl rubber (bromobutyl and chlorobutyl) has emerged as the standard precisely because it meets the aqueous environment's requirements on all the critical dimensions.
Low extractables into aqueous media
+
-
The primary chemical concern for a rubber stopper in contact with an aqueous injection is the migration of extractable species from the rubber compound into the aqueous phase - including residual vulcanisation agents, antioxidants, plasticisers, heavy metals, and processing aids. Butyl rubber (bromobutyl and chlorobutyl) has a well-characterised, relatively low extractable profile in aqueous conditions, making it the baseline specification for most aqueous injectable products under USP <381> and EP 3.2.9.
For specific products where the aqueous formulation is particularly sensitive to extractables - biologics, peptide injectables, or high-pH buffered solutions - a low-extractable grade butyl stopper can be specified for enhanced compliance with ICH Q3D elemental impurity guidance and the evolving leachables framework.
Autoclave compatibility
+
-
Aqueous injectable vials are typically terminally sterilised by moist heat autoclave - sealed and then exposed to saturated steam at 121°C for the defined sterilisation cycle. The combination cap's butyl stopper must maintain its dimensional and mechanical properties through this cycle without swelling, deforming, or losing seal force - and must not absorb or release any additional extractable species into the aqueous product during the autoclave exposure.
Butyl rubber is inherently resistant to steam and aqueous environments at autoclave temperatures. The combination cap's aluminium shell and PP inner liner are also autoclave-rated. The complete 4-layer combination cap assembly is validated for standard 121°C saturated steam autoclave cycles.
Performance - three clinical demands
Three performance requirements for aqueous injection use - all met by the combination cap
An aqueous injectable vial's combination cap is accessed in clinical settings - wards, operating theatres, pharmacies, and infusion centres - under varying conditions and by different personnel. Its performance must be consistent and reliable every time.
Clinical use · IV preparation · IM administration
Whether a pharmacist is preparing an IV infusion bag, a nurse is drawing up an IM injection, or a clinician is accessing a multi-dose vial in an emergency, the needle must penetrate the rubber stopper smoothly and with a consistent, low force - regardless of needle gauge, angle of insertion, or number of prior punctures in a multi-dose vial. The butyl stopper's Shore A hardness, surface finish, and siliconization level are optimised for consistent penetration performance across standard hypodermic needle gauges used in aqueous injection practice.
✓ Works with standard hypodermic needle gauges (18G–26G)
✓ Consistent performance across multiple punctures
✓ No coring - no rubber particles in the withdrawn solution
Multi-dose · repeated access · sterility maintained
Many aqueous injectables - particularly in hospital settings - are supplied as multi-dose vials where multiple doses are withdrawn from the same vial over time. Each withdrawal punctures the stopper, and the combination cap must self-seal each puncture to prevent microbial ingress between doses. The elastomeric memory of butyl rubber closes the puncture channel immediately after needle withdrawal - confirmed by the post-puncture seal test in USP <381>. A preservative system in the formulation works alongside the stopper's self-sealing to maintain multi-dose vial sterility.
✓ Immediate self-seal after each needle withdrawal
✓ Tested to USP <381> post-puncture seal criterion
✓ Supports multi-dose use in clinical and hospital settings
Product identification · error prevention · ward safety
In clinical environments where multiple injectable products are handled simultaneously, the colour of the flip off tab provides a rapid visual identification cue - reducing the risk of product mix-up at the point of care. Colour coding of injectable vial caps is a recognised clinical safety practice in hospital pharmacy and ward settings. The combination cap's PP flip tab can be produced in any colour, and custom colour schemes can be specified to align with a product's broader labelling and identification system or hospital formulary conventions.
✓ Custom colour available for any product line
✓ Supports clinical safety and product identification
✓ Tamper evidence - intact tab confirms vial not previously opened
Size selection - 13mm vs 20mm for aqueous injectables
13mm and 20mm - the right size for your aqueous injectable vial
The combination cap size must match your vial's neck finish diameter. Both 13mm and 20mm combination caps are available with the same 4-layer composite construction, aqueous-compatible butyl stopper, and autoclave rating.
small aqueous injection vial cap
2ml · 3ml · 5ml · single-dose injectables
✓ 2ml–5ml aqueous injectable vials with 13mm neck finish
✓ Single-dose IV push, IM, and SC injectables
✓ Diagnostic agents, hormones, small-volume biologics
✓ Paired with 13mm bromobutyl rubber stopper
standard aqueous injection vial cap *
5ml · 10ml · 20ml · multi-dose
✓ 5ml–50ml aqueous injectable vials - most common hospital format
✓ IV antibiotics, analgesics, anticoagulants, electrolytes
✓ Multi-dose vials for insulin, vaccines, local anaesthetics
✓ ISO 8362-2 tubular vial neck standard - 20mm
Confirm the neck finish from your vial drawing - not from the fill volume
A 5ml aqueous injectable vial may have either a 13mm or 20mm neck finish depending on the vial manufacturer and glass type (tubular vs moulded). Always confirm the neck outer diameter from your vial's dimensional drawing or by measuring before ordering combination caps. A 20mm cap will not crimp correctly onto a 13mm neck, and vice versa. We confirm compatibility from your vial sample or technical drawing at no charge.
use cases - aqueous injectable categories
Where the combination cap for aqueous injection is used - clinical and hospital applications
The combination cap for aqueous injection serves virtually every category of aqueous parenteral drug product - from high-volume hospital antibiotics through to specialised multi-dose vaccines.
Multi-dose aqueous vials
Repeated access · self-sealing critical
Multi-dose aqueous injectables rely particularly on the self-sealing property of the butyl stopper to maintain vial sterility across multiple accesses - the combination cap's post-puncture seal performance is tested and documented for this application specifically.
Insulin (multi-dose vials, 10ml)
Local anaesthetics (lidocaine, bupivacaine)
Heparin and low-molecular-weight heparins
Multi-dose vaccines (influenza, hepatitis B)
infusion additives & electrolytes
High-volume · aqueous buffer solutions
Concentrated electrolyte solutions and infusion additives - potassium chloride, magnesium sulfate, sodium bicarbonate - added to IV infusion bags under aseptic technique require vials with combination caps that remain sterile through the entire additive preparation process.
Potassium chloride (KCl) concentrate
Magnesium sulfate (MgSO₄) injection
Sodium bicarbonate infusion concentrate
Calcium gluconate injection
hospital injectables
IV · IM · SC · ward stock
The combination cap is the standard closure for all hospital formulary injectable drugs - antibiotics, analgesics, antifungals, anticoagulants, and supportive care agents - in vial format. Colour-coded caps help ward and pharmacy staff rapidly identify products at the point of care.
IV antibiotics (cephalosporins, penicillins, carbapenems)
Analgesics and anaesthetics (morphine, ketamine)
Anticoagulants and thrombolytics
Emergency and resuscitation drugs
compliance - standards applicable to aqueous injection closures
USP, EP, and ISO - the standards that apply to this combination cap
Three standards directly govern the rubber stopper component and the overall closure system of the combination cap for aqueous injection - providing the regulatory compliance evidence required for submission in US, European, and international markets.
USP <381>
Elastomeric Closures for Injections
United States Pharmacopeia
Defines physicochemical testing requirements for rubber closures used with injectable drug products - the baseline regulatory requirement for aqueous injectable vials in the US market. Tests include pH, colour, reducing substances, heavy metals, extractable zinc, and biological reactivity.
✓ Physicochemical tests on aqueous extract
✓ Self-sealing post-puncture test
✓ Fragmentation (no coring) test
EP 3.2.9
Rubber Closures for Aqueous Preparations
European Pharmacopoeia
The European standard specifically for rubber closures used with aqueous parenteral preparations - the EP counterpart to USP <381> but with its own extract preparation and test acceptance criteria. Products for European or EP-referencing markets require EP 3.2.9 compliance documentation for the stopper component.
✓ Aqueous extract preparation (WFI, 121°C)
✓ Absorbance, pH, reducing substances
✓ Penetrability and fragmentation
ISO 8362-5
Rubber Closures for Injection Vials
International Standard
The international dimensional and performance standard for rubber closures used with injection vials manufactured per the ISO 8362 vial series - covering 13mm and 20mm neck finishes. ISO 8362-5 compliance supports regulatory submissions in international markets outside the primary US/EU pharmacopoeial frameworks.
✓ 13mm and 20mm dimensional specification
✓ Physicochemical and penetrability tests
✓ International market regulatory support
complete specifications
Combination cap for aqueous injection - full specification reference
Reference specifications for the 13mm and 20mm combination cap for aqueous injection vials.
| Parameter | 13mm | 20mm |
|---|---|---|
| Construction | ||
| Layers | 4-layer composite ★ | 4-layer composite ★ |
| Flip tab | PP - custom colour | PP - custom colour |
| Outer cap | Aluminium crimp shell | Aluminium crimp shell |
| Inner liner | PP inner cap | PP inner cap |
| Stopper | Bromobutyl / chlorobutyl | Bromobutyl / chlorobutyl |
| Aqueous compatibility | ||
| pH range | pH 3–10 | pH 3–10 |
| Temperature range | −40°C to +121°C (autoclave) | −40°C to +121°C (autoclave) |
| Aqueous solvents | WFI, NaCl, dextrose, buffers | WFI, NaCl, dextrose, buffers |
| Performance | ||
| Seal | Hermetic · CCIT tested | Hermetic · CCIT tested |
| Self-sealing | Yes - USP <381> tested ★ | Yes - USP <381> tested ★ |
| Sterilization | Autoclave 121°C / gamma | Autoclave 121°C / gamma |
| Compliance & supply | ||
| Stopper standard | USP <381> · EP 3.2.9 | USP <381> · EP 3.2.9 |
| Closure standard | ISO 8362-5 | ISO 8362-5 |
| Sample | Free sample available | Free sample available |
| Colour options | Custom - any colour | Custom - any colour |
who orders this combination cap
Combination caps for aqueous injectables - who specifies and buys
The 13mm and 20mm combination cap for aqueous injection is specified across the pharmaceutical manufacturing and hospital supply chain wherever aqueous parenteral drug products are filled in vials.
antibiotic manufacturers
High-volume IV injectables
High-volume producers of IV antibiotics in 5ml–20ml vials - one of the largest aqueous injectable categories by volume - requiring consistent, autoclave-rated combination caps in large batch quantities.
hospital pharmacy & CIVAS
Centralised IV additive services
Hospital centralised IV additive services (CIVAS) and pharmacy manufacturing units producing batch-prepared aqueous injectable admixtures for ward use, requiring pharmacopoeial-compliant vials and combination caps.
generic injectable producers
Analgesics · electrolytes · supportive care
Generic pharmaceutical manufacturers producing aqueous injectable analgesics, electrolyte concentrates, and supportive care drugs in vial format for hospital formulary supply.
vaccine manufacturers
Multi-dose vaccine vials
Vaccine producers filling multi-dose aqueous vaccine vials where self-sealing performance across repeated punctures is critical to maintaining sterility of the remaining doses.
CDMOs & contract full-finish
Multi-client aqueous fill lines
Contract fill-finish organisations managing multiple client products on aqueous injectable filling lines - standardising on combination cap specifications validated for their autoclave cycles and capping equipment.
compounding pharmacies
Sterile aqueous compounding · USP <797>
Compounding pharmacies preparing sterile aqueous injectable preparations under USP <797>, needing combination caps with full pharmacopoeial compliance documentation for their quality records.
Sealed for Aqueous. Safe for Clinical Use.
Combination cap for every aqueous injectable format.
Tell us your vial size (13mm or 20mm), formulation type, and sterilisation method - we'll confirm the combination cap specification, aqueous compatibility, and arrange a free sample within 48 hours.
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