ISO 8536-6:2016

Overview

ISO 8536-6:2016 specifies requirements for freeze drying closures for infusion bottles used in lyophilization (freeze-drying) of drugs and biological materials. It covers the shape, dimensions, materials, performance tests and labelling for elastomeric closures intended for use with infusion glass bottles described in ISO 8536-1. The standard applies to single‑use closures (dimensional requirements exclude barrier‑coated closures) and includes normative test methods for fragmentation (coring), spike penetration, sealability and residual moisture.

Key topics and technical requirements

• Scope and designation
  • Defines closure design and how to designate a compliant product (e.g., “Freeze drying closure ISO 8536‑6 - 32”).
• Dimensions and design
  • Shape and dimensional limits are given (see Table 1 and Figure 1 in the standard); spacers and positioning elements are covered to permit sublimation position and final insertion.
• Materials
  • Elastomeric materials must meet the performance requirements in Clause 7 and withstand two steam‑autoclave cycles at (121 ± 2) °C for 30 min without loss of function. Barrier‑type closures are treated separately.
• Physical performance
  • Hardness: ±5 Shore A (or ±5 IRHD if tested per ISO 48).
  • Fragmentation (coring): ≤ 20 fragments ≥ 50 µm per 10 piercings (Annex A).
  • Spike penetration: maximum 80 N, average < 75 N; closure must not be pushed into bottle (Annex B).
  • Spike retention/sealability: full penetration without leakage for 4 h; spike must not be pulled from closure (Annex C).
  • Residual moisture: guidance and test method provided (Annex E); manufacturers should recommend time/temperature profiles to reduce moisture without damaging elastomer.
• Chemical and biological
  • Chemical extractables and biological test requirements reference ISO 8871‑1 and ISO 8871‑4.
• Labelling
  • Packed closures that comply can be labelled per Clause 5.

Applications and users

ISO 8536‑6 is primarily used by:

• Medical device and packaging manufacturers designing or supplying freeze drying closures for lyophilized drug containers.
• Pharmaceutical formulation, vial‑filling and lyophilization engineers validating container closure systems.
• Quality assurance, regulatory and procurement teams specifying supplier acceptance criteria and stability test requirements.
• Sterilization validation and packaging development groups concerned with residual moisture, autoclave compatibility and integrity during storage and transport.

Practical applications include supplier specifications, incoming inspection, stability program inputs for lyophilized products, and design validation for lyophilization-compatible closures.

Related standards

• ISO 8536‑1 (Infusion glass bottles)
• ISO 8536‑3 (Aluminium caps)
• ISO 8871‑1 / ISO 8871‑4 (elastomeric parts: chemical/biological)
• ISO 7619‑1 (durometer/Hardness)
• ISO 3302 (rubber tolerances)
• Referenced GMP/cGMP guidance (e.g., ISO 15378) for manufacturing controls

Keywords: ISO 8536‑6:2016, freeze drying closures, lyophilization closures, infusion bottles, elastomeric closures, residual moisture, coring, spike penetration, sealability.