Pyrogenicity of E. coli 055:b5 endotoxin by the USP rabbit test--a HIMA collaborative study.

A Collaborative Study, initiated under the auspices of the Health Industry Manufacturers Association, was designed to determine a level of a reference endotoxin that could be considered pyrogenic in a cross section of rabbit colonies used for USP pyrogen testing. This study was designed to establish, in a definitive way, a reference level against which the Limulus Amebocyte Lysate Test(LAL) could be standardized. Since the LAL test is much more sensitive than the rabbit test in the detection of pyrogens, its equivalency to the rabbit test has to be measured with a pass/fail level that has some relationship with the level of pyrogen that is considered pyrogenic in the rabbit. The Collaborative Study establ;ished with 95% confidence that a staistically avrage laboratory wsill attain 50% pass/fail results at some concentration level above 0.098 ng/ml of Difco E. coli 055:B5 endotoxin (Lipopolysaccharide B). It is recommended that 0.1 ng/ml be set as the "standard reference pyrogenic activity" against which the Limulus Amebocyte Lysate Test (LAL) is to be compared. If an LAL test can be performed to demonstrate a test failure rate significantly greater than 50% at 0.1 ng/ml of Difco E. coli 055:B5 endotoxin, that test will be considered qualified for use under the conditions opf evaluation as equivalent to the USP rabbit test.