title: Comparison of temperature rise interpretations between European and United States Pharmacopeias' pyrogen tests.
abstract: The European Pharmacopeia (EP) and the United States Pharmacopeia (USP) pyrogen test for parenterals involve the measurement of the temperature rise in rabbits following the intravenous injection of the test solution. Between the two methods, the conditions for the result "pyrogen free" or "pyrogen", as well as the number of rabbits tested, differ substantially. Therefore, both methods were compared with respect to the differences in temperature rise interpretations with special attention to the selectivity of the tests. To exclusively study the temperature rise interpretations, the temperature measurements were simulated with models. With an increasing mean temperature rise, an intermediate range exists where the probability of "pyrogen free" and of "pyrogen" cannot be ignored. A single pyrogen test still gives an unambiguous result, but in this range, the probability is rather high that additional tests will not reproduce the same result. This range is approximately 0.3 degrees C wide for the USP test and 0.2 degrees C wide for the EP test. Simulating the temperature rise with a normally distributed model, the intermediate range is narrower for the interpretation according to the EP than the USP. For a USP test, the probability of the test result "pyrogen free" decreases as lower mean temperature rises. However, the two methods are similar in the high probability range for the presence of pyrogens. At the edge of the intermediate range, a slight mean temperature rise of 0.05 degrees C significantly changes the probability of a pyrogen result. Within a rather wide mean temperature rise range (approximately 0.15 degrees C wide), a product will reliably fulfil the EP requirements but not the USP requirements. These main statements are rather robust and do not depend significantly on the model used. Different temperature rise distributions only result in negligible variations in the interpretation of the tests. Information more detailed than mean temperature rise and standard deviation of the temperature rises is not absolutely necessary. For product quality, it is much more useful to review and interpret all individual temperature rises measured than to interpret the results of the pyrogen test only [corrected].
authors.affiliation: ZLB Bioplasma AG, Bern, Switzerland. juerg.tschumi@zlb.com
authors.forename: Jürg
authors.initials: J
authors.lastname: Tschumi
mesh_terms: D000818:Animals; D001831:Body Temperature / Q000187:drug effects*; D005060:Europe; D008954:Models, Biological; D010602:Pharmacopoeias as Topic / Q000592:standards*; D011336:Probability; D011749:Pyrogens / Q000494:pharmacology*; D011817:Rabbits; D012015:Reference Standards; D014481:United States
chemical_list: D011749:Pyrogens