Low endotoxin recovery (LER), also known as endotoxin masking, is a recently described but long-observed phenomenon. LER is the inability to recover known amounts of purified endotoxin from biological formulations. Check out our quick resources below to learn more. 

Poster

Articles

Presentations

  • “Summary of LER Discussions” (Dr. James Cooper, Bacterial Endotoxin Summit) Request a PDF copy »
  • “Comparative In Vitro and In Vivo Low Endotoxin Recovery (LER) Assessment” (John Dubczak, 9th Annual PDA Global Conference on Pharmaceutical Microbiology) Request a PDF copy »
  • “Endotoxin Potency Change in the LAL Reactivity and Its Relationship With Pyrogenicity” (Masakazu Tsuchiya, PhD, 9th Annual PDA Global Conference on Pharmaceutical Microbiology) Request a PDF copy »

Webinars

LER Impact

LER has become such a significant issue that recently an entire PMF Bacterial Endotoxin Summit (BES) was devoted to the topic. Scientists at the summit largely agreed that LER is not a public health concern. There have been no reported endotoxin outbreaks due to a failure of the limulus amebocyte lysate (LAL) endotoxin screening test.

LER does, however, present a problem in validating product hold times. Chelating agents combined with surfactants that are common in biological formulations are particularly problematic.

Next Steps

More research must be done to both understand and address LER. We are actively studying a variety of purified and native endotoxin preparations using all available in vitro and in vivo techniques. Our Endosafe® scientists have examined several formulations that appear to denature purified lipopolysaccharides (LPS) so they are no longer detectable by the LAL test or monocyte activation test (MAT), or in rabbits.

They have also defined native endotoxin preparations that approximate the natural endotoxin contaminants found in pharmaceutical manufacturing operations. These preparations have been shown to be resistant to LER. The in vitro and in vivo characterizations of the native endotoxin preparations continue to be investigated.

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The feature article in this issue of the Endosafe® Times reviews the development of endotoxin test methods and describes how the innovative LAL-dependent systems became standard compendial methods.

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