ISO 11737-3:2023

Overview

ISO 11737-3:2023 - Sterilization of health care products - Microbiological methods - Part 3: Bacterial endotoxin testing (BET) - specifies general criteria for determining bacterial endotoxins on or in health care products, components, or raw materials using amebocyte lysate reagents. The standard covers BET methods that use Limulus or Tachypleus amebocyte lysate and focuses on practical test selection, validation, routine testing and data interpretation. It does not apply to pyrogens other than bacterial endotoxins, and other detection technologies (e.g., recombinant Factor C, monocyte activation) are excluded.

Key topics and requirements

• Scope and exclusions: Applies to bacterial endotoxins; excludes non-endotoxin pyrogens and alternative detection methods. It does not set specific endotoxin limit values.
• BET methods covered: Gel-clot technique; kinetic and end‑point methods including chromogenic and turbidimetric approaches.
• Method suitability / validation: Requirements for product and method suitability testing, interference checks, and sample preparation for solids and aqueous products.
• Critical test parameters: Control of temperature, time, pH, equipment, reagents and use of amebocyte lysate reagents.
• Endotoxin limit considerations: Guidance on endotoxin limit concepts, calculation for extract solutions and the Maximum Valid Dilution (MVD) to ensure reliable testing.
• Reagent and analyst qualification: Criteria for reagent qualification and analyst competency for both gel-clot and kinetic/turbidimetric methods.
• Routine testing & monitoring: Guidance on limit tests, quantitative assays, result interpretation, statistical analysis and test frequency.
• Maintenance & change control: Requirements for maintaining BET methods when product or process changes occur.
• Alternatives to batch testing: Risk‑based criteria and process assessment to support alternatives to end-of-batch testing (with annexed guidance).
• Annexes: Informative guidance on BET practices, history/background, out-of-specification investigations, in‑process monitoring, and risk assessment.

Practical applications

• Release testing for non-pyrogenic claims on medical devices, components and raw materials.
• Validation and qualification of endotoxin test methods during product development and manufacturing.
• In-process monitoring and routine quality control in pharmaceutical and medical device manufacturing.
• Supporting change-control, failure-investigation and risk assessments for endotoxin control strategies.
• Contract testing laboratories implementing standardized BET procedures.

Who should use this standard

• QC microbiologists and laboratory managers
• Sterilization and validation engineers
• Regulatory and compliance professionals in medical device and pharmaceutical industries
• Contract testing labs and CROs conducting BET

Related standards

• ISO 11737 series (other parts on sterilization/bioburden testing)
• ISO 10993 series (biological evaluation of medical devices) - referenced for non-microbial pyrogens and biocompatibility context

Keywords: ISO 11737-3:2023, bacterial endotoxin testing, BET, amebocyte lysate, gel-clot, chromogenic, turbidimetric, endotoxin limit, MVD, sterilization of health care products.