Second international standard for endotoxin: calibration in an international collaborative study

Abstract

On behalf of the World Health Organization, 26 scientists in 13 countries calibrated a candidate international standard for endotoxin and compared it with the Pharmacopoeial standards of the US, Europe and Japan. The study showed that the candidate standard is suitable to serve as the second international standard for endotoxin for all applications, with an assigned unitage of 10,000 international units (IU)/vial, with 1 IU = 1 EU (FDA/USP endotoxin unit). This value maintains continuity of unitage with EC5 (the primary calibrant for the first international standard), EC6 (the current FDA/USP standard), the Japanese Pharmacopoeia Standard and commercial preparations of Limulus lysate. This value is also consistent with calibration of the candidate standard in terms of the European Pharmacopoeia Standard, BRP-2. The establishment of this international standard for endotoxin will permit the global harmonisation of unitage for standards of endotoxin.