Bacterial Endotoxins Test
Bacterial Endotoxins Test (BET) / Limulus Amebocyte Lysate (LAL) Test
What a definition is not
A definition is SPEQ’s plain-language decode of how a term is used in practice, cited to the documents that define it. It is a practitioner reference, not legal or regulatory advice, it does not replace the definition in the source, and where a regulator’s wording differs the regulator’s wording governs.
A compendial assay that detects and quantifies bacterial endotoxin (lipopolysaccharide from Gram-negative bacterial cell walls) in parenteral drug products, water systems, and medical devices, using Limulus Amebocyte Lysate reagent derived from horseshoe crab blood. Gel-clot, turbidimetric, and chromogenic kinetic formats are all compendial; recombinant Factor C is an accepted non-animal-derived alternative.
Endotoxin is heat-stable and not eliminated by sterilization, so BET is a distinct release requirement from the sterility test — a product can pass sterility testing yet fail BET if endotoxin was introduced upstream, for example through inadequately depyrogenated components or poor water-system control.
Results are reported relative to an endotoxin limit calculated from the product’s maximum human dose and the patient’s body weight, so the acceptance criterion is product- and route-specific rather than a single fixed number.
Recombinant Factor C and other non-animal-derived reagents are gaining regulatory acceptance as an alternative to LAL, driven by sustainability pressure on horseshoe crab harvesting, but require their own validation against the compendial gel-clot reference method.
- —Detects endotoxin, not general microbial contamination — a separate hazard from viable bioburden or sterility failure.
- —Endotoxin limit is calculated per product from the maximum human dose per hour and threshold pyrogenic dose.
- —Gel-clot is the reference method; turbidimetric and chromogenic kinetic methods require validation against it.
- —Water for Injection and Purified Water systems are routinely monitored by BET as a process control.
- —Recombinant Factor C is an accepted non-animal-sourced alternative reagent.
USP <85>; Ph. Eur. 2.6.14; EU GMP Annex 1 (2022)
Frequently asked questions
What does Bacterial Endotoxins Test stand for?
Bacterial Endotoxins Test stands for Bacterial Endotoxins Test (BET) / Limulus Amebocyte Lysate (LAL) Test.
What is Bacterial Endotoxins Test?
A compendial assay that detects and quantifies bacterial endotoxin (lipopolysaccharide from Gram-negative bacterial cell walls) in parenteral drug products, water systems, and medical devices, using Limulus Amebocyte Lysate reagent derived from horseshoe crab blood. Gel-clot, turbidimetric, and chromogenic kinetic formats are all compendial; recombinant Factor C is an accepted non-animal-derived alternative.
Which regulations cover Bacterial Endotoxins Test?
USP <85>; Ph. Eur. 2.6.14; EU GMP Annex 1 (2022)