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<1085.1> Use of Recombinant Reagents in the Bacterial Endotoxins Test FAQs

A prospectus on a new chapter <1085.1>, Use of Recombinant Reagents in the Bacterial Endotoxins Test was published by USP on May 29, 2020, and interested stakeholders were invited to comment.  USP received a total of eleven (11) communications commenting on the prospectus.  Responses to the five most Frequently Asked Questions (FAQ) or Comments are provided below.

  1. Why did USP cancel proposed revisions to <85> in favor of the introduction of a new informational chapter?
    USP welcomes proposals for analytical procedures alternative to compendial methods for inclusion in chapters numbered below 1000.  After a collective, objective review of all pertinent public domain literature, and public comments received, the Expert Committee determined that the assurance of patient safety using recombinant reagents requires additional, rigorous and comprehensive study specifically related to comparability.

  2. There is published literature that suggests recombinant reagents are equivalent to LAL reagents, are those data sufficient to include recombinant reagents in <85> at this time?
    USP General Notices 6.30 indicates that validation of alternative assays consists of three components: 1) Analytical capability per USP <1225> (as applicable), 2) product/method suitability, and 3) test result comparability.  Published data on the use of recombinant reagents in Bacterial Endotoxin Testing employing calibration standards and analytes (Reference Standard Endotoxin (RSE) and Control Standard Endotoxin (CSE)) address only points 1 and 2, but do not provide data on the comparability of test results on articles containing autochthonous endotoxins that have been known to cause injection fever for over 100 years.  

    Additionally, studies that claim to demonstrate “comparability” have generally used test articles with no detectable endotoxins activity, meaning below the LOQ of the test method.  It is not possible to claim comparability when the impurity that is being measured, in this case, endotoxins activity, is absent in the test article at quantifiable levels.  The recovery of the analyte (RSE or CSE) does not experimentally confirm the alternative method’s ability to recover natural product contaminants.

  3. There are concerns that continued use of LAL will negatively impact the horseshoe crab and red knot bird populations – does the Expert Committee have a position on this issue?
    No. The Expert Committee works in support of USP’s public commitment to seeking alternatives to animal-based products wherever possible. However, the Expert Committee’s purview is the scientific evaluation of alternative procedures in an effort to ensure analytical capability, continued product quality, and, ultimately, patient safety.

  4. Why was the horseshoe crab, Carcinoscorpius rotundicauda not mentioned in the prospectus?
    That was an inadvertent omission from the prospectus. USP takes no position regarding the horseshoe crab species from which recombinant zymogen proteases are cloned.  The comparability of any analytical reagent, regardless of source, is predicated on its analytical performance in comparison to the current compendial reference methods.

  5. What does USP plan to do next with respect to <1085.1>? 
    The proposed chapter <1085.1> Use of Recombinant Reagents in the Bacterial Endotoxins Test, will be published in PF 46(5) (September- October 2020).  In keeping with the USP process, we invite stakeholder comments on the content of any newly proposed or revised general chapter. The Expert Committee will review all comments in response to the proposal, evaluate any submitted suggested revisions on the scientific content of the draft, and make changes as necessary to improve clarity and enhance reader understanding.  

Updated August 28, 2020