How do endotoxin tests work?

Bacteria can be found everywhere—even sometimes in clean rooms. That’s a problem for manufacturers of drugs and medical devices that are injected or implanted. Even if manufacturers can remove the microbes themselves, molecular traces can remain. If they make their way into the body, these toxins activate a powerful immune response, causing fever and inflammation. To make sure these microbial signatures, called pyrogens, are absent from injected drugs, manufacturers test ingredients, containers, water systems, and finished drug products for specific molecules in . The longest-used assay depends on ingredients from wild animals, but regulators are now approving the use of animal-free alternatives. Here’s how these tests work. LAL: The legacy test A pyrogen is any molecule that can cause a fever if injected. One subset of pyrogens are lipopolysaccharides (LPS), also called endotoxins. These glycolipids, found in the outer membrane of gram-negative bacteria, comprise lipid A, a core oligosaccharide, and