In the world of pharmaceutical and medical device manufacturing, there are various quality control tests that may be required for distinct product types from separate regulatory agencies. With next generation medical device manufacturing, such as combination drug devices, the line between Bacterial Endotoxin Testing (BET) and Extractables and Leachables (E&L) Testing may become blurred. In fact, some may find considerable overlap between the goals of these methods with regards to product and patient safety.
Bacterial Endotoxin Testing: Background, Purpose and Testing Methodology
Bacterial Endotoxin Testing (BET) is performed to detect the presence of bacterial endotoxin in a drug product or medical device. Endotoxins, or lipopolysaccharides (LPS), are a type of pyrogen derived from the outer membrane of gram-negative bacteria. When introduced into the bloodstream, endotoxin can induce a febrile response, among other pyrogen-triggered systemic reactions, including septic shock in severe cases.
Any drug product or medical device that comes into contact with the bloodstream or cerebrospinal fluid is required to be tested for bacterial endotoxin following testing parameters outlined in United States Pharmacopeia (USP) Chapter <85>. Drug and product-specific monographs define the endotoxin limit required for their testing, meaning that the final product must have an endotoxin concentration lower than that defined limit.
Endotoxin testing is performed using Limulus Amebocyte Lysate (LAL) reagent, which is biological in nature and utilises a clotting mechanism found in the Atlantic Horseshoe Crab. Although the assay was initially established as a qualitative test, there are also various quantitative test methods that allow for the quantification of bacterial endotoxin in either a
turbidimetric or colourimetric assay.
The assay, being biological in nature, establishes concentration in units of biological activity, or “Endotoxin Units (EU)”, rather than in mass or size. At the molecular level, LPS naturally exists in various structures and formations, which
can, in turn, affect the biological activity level of the molecule. Therefore, even if someone were to place two LPS molecules of the same mass side by side, their biological activity level
may greatly differ.
