USP <85> Test for Endotoxin
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Endotoxins are disease-causing components of Gram-negative bacteria that cause harmful immunological reactions. Endotoxins may remain in medical devices and pharmaceuticals even after bacteria have been killed by sterilization.
Endotoxin testing is essential for ensuring the safety of injectable drugs, implantable medical devices, and other sterile products. Even trace amounts of endotoxins from Gram-negative bacteria can trigger serious immune responses, including fever, inflammation, and septic shock. USP-compliant endotoxin testing provides a reliable means to minimize patient risk.
Microchem’s endotoxin testing service provides fast, accurate results.
The USP <85> test has three different techniques that can be used to ascertain a product’s endotoxin concentration with lysate. The three endotoxin methods include:
- Gel-Clot Technique
- Turbidimetric Technique
- Chromogenic Technique.
Microchem provides testing with the Chromogenic version of USP <85> via Pierce’s Chromogenic Endotoxin Quant Kit. The test is performed by generating a standard curve from prepared endotoxin standard solutions using their known concentrations and the optical density obtained by testing personnel. The equation from the standard curve is used to determine the endotoxin concentration of the product from its optical density.
Summary of the USP <85> Test Procedure
- At least three standard endotoxin solutions are prepared according to the manufacturer’s instructions.
- A predetermined volume of reconstituted lysate is added to each standard solution and test sample and allowed to remain undisturbed for a predetermined amount of time.
- At the end of the lysate’s time, the chromogenic substrate is added to each solution and allowed to remain undisturbed for a predetermined period of time. The opaqueness of the color is based on the endotoxin concentration.
- Once that time is completed, acetic acid is used to stop the reaction.
- The optical density of each solution is determined at 405 nm.
- The standard endotoxin solutions are used to generate a standard curve. This standard curve is used to interpolate the endotoxin concentration of the test sample solutions from their optical densities.
- The endotoxin concentration of the test sample solution must be below the endotoxin limit.
- To determine if the product contains any factors that would interfere with the measuring of endotoxins, the test outlined above is repeated with a test sample solution that has a specific amount of endotoxins introduced to it.
Sources:
United States Pharmacopeia. (2012, December 01). <85> Bacterial Endotoxins. https://www.usp.org/harmonization-standards/pdg/general-methods/bacterial-endotoxins
U.S. Food and Drug Administration. (2014, November 17). Bacterial Endotoxins/Pyrogens. https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/inspection-technical-guides/bacterial-endotoxinspyrogens