2019 Volume 22 Pages 13-16
Low Endotoxin Recovery (LER) is a phenomenon of endotoxin activity decrease in a matrix containing a chelating agent and a detergent, and is a controversial topic in the biopharmaceutical field. LER raised a questions on the target of the Bacterial Endotoxins Test (BET). This includes endotoxin activity change by samples and undetectable endotoxin in samples. We have been measuring endotoxin activity, not the amount of endotoxin in a sample by the BET. Endotoxin activity in a sample can be changed by a different condition, like LER. There may be a status of endotoxin that cannot be detected by the BET. There was difference in LER resistance between purified endotoxin and naturally occurring endotoxin. Although there may be the highest endotoxin activity in a sample under a different condition, the highest activity is not the target of the BET. The endotoxin in a sample should be measured as is. There may be undetectable endotoxin, but we do not have enough information to discuss about its effects on human health. This should be studied in the future.