USP <85> Bacterial Endotoxin Validation
ARL Bio Pharma utilizes the kinetic turbidimetric method described in USP <85> Bacterial Endotoxins Test to provide results. An endotoxin test detects toxins that are released from the cell wall of disrupted gram-negative bacteria. This is a reaction over time test that quantitates the amount of endotoxin in a sample compared to a standard curve. This article discusses USP <85> challenges and why method validation is important to provide consistent results.
The most common challenge encountered while performing endotoxin testing is that many drug products cause the assay reaction to slow down (inhibition) or speed up (enhancement) during the testing process, which does not allow for an accurate result to be obtained. Those properties which cause the inhibition or enhancement must be overcome to obtain a reliable and repeatable test result. Microbiologists performing testing must determine the degree in which inhibition or enhancement is occurring. This is done by adding known amounts of endotoxin to test samples and comparing the results to those known values. If there is no inhibition or enhancement, results from the test samples spiked with a known amount of endotoxin will be the same as the expected results. Inhibition would artificially lower results for the test sample, and enhancement would increase results for the test sample, relative to the expected spike concentration.
Once inhibition or enhancement is understood, microbiologists can develop a plan of action to overcome those sample properties.