LER occurs when a product formulation causes endotoxin to mask, aggregate, or bind to particulates or container surfaces, rendering it invisible to the standard kinetic chromogenic or turbidimetric assays—without losing its biological activity. Classic culprits include:
TR-82 emphasizes that LER is not simply an assay artifact. It recommends orthogonal methods (e.g., in vitro pyrogen test using human whole blood or monocyte activation test) to determine whether undetected endotoxin retains pyrogenicity. pda technical report 82 pdf
: Studies should be performed on three product batches under process-relevant conditions. LER occurs when a product formulation causes endotoxin
For decades, the pharmaceutical industry relied on a simple, elegant assumption: If a drug product passes the initial Bacterial Endotoxins Test (BET, commonly known as the LAL test), it is safe from endotoxin contamination. However, in the mid-2000s, a disturbing phenomenon shattered this assumption. Manufacturers observed that while an initial sample tested negative for endotoxins, the same product stored for weeks or months would later show contamination. Worse yet, spiked samples (deliberately contaminated for testing) yielded falsely low readings over time. : Studies should be performed on three product
: Premium members may be eligible for a free annual technical document download by contacting the association directly. Parenteral Drug Association Overview of TR 82 Content