Collaborating with USP on its Bacterial Endotoxin Test Protocol and Bioreactivity Draft Monographs

1 February 2022
Advanced Therapy Medicinal Products

With a clear objective of setting standards for the industry and protecting patients worldwide, the USP is a key partner of BioPhorum. Ensuring that the industry position defined through the BioPhorum collaboration is reflected back to the USP is also one of BioPhorum’s key objectives. 

Two recent documents typify BioPhorum’s approach to this collaboration and how it provides expert feedback on consultations.

Industry feedback on Bacterial Endotoxin Test (BET) Protocol

The absence of bacterial endotoxins in parenteral products, as most biologics are, is a key attribute to ensure patient safety as they can lead to a catastrophic outcome. The compendial test described in this USP uses the lysate from the blood cells of horseshoe crabs (known as the LAL method, standing for limulus amebocyte lysate). An alternative known as the Recombinant Factor C (rFC) method that uses only synthetic reagents, as opposed to animal-sourced ones, was developed, and patented in 1997, and has been successfully implemented since 2018.

The rFC method is now a compendial method in the European and Chinese Pharmacopoeias. The Japanese Pharmacopeia allowed the rFC method as an alternative in its XVIII edition and is moving toward a compendial status in a couple of years. Also, the South Korean Agency conducted an independent study with manufacturers and found equivalency between rFC and LAL. Overall, rFC has been accepted in more than 60 countries.

The USP has been considering publication of a general method for the rFC method for several years; however, it is looking for additional insurance that the new method is as reliable as the current LAL compendial method. It therefore designed a study to collect data comparing the rFC and the lysate reagents method described in <USP85> Bacterial Endotoxins Test. It aims to compare levels of endotoxin activity arising from autochthonous Gram-negative bacteria present in pharmaceutical (deionized) water samples, which are analyzed by both the current monographed methodology and recombinant reagents.

The USP has published details of the proposed study in Bacterial Endotoxin Test (BET): A USP Comparability Study of Recombinant Reagents (Recombinant Factor C and Recombinant Cascade) to Lysate Reagents (LAL) and has asked for industry comments.

Using a select group from its Regulatory and Microbiological Teams, BioPhorum has published Industry feedback on Bacterial Endotoxin Test (BET). It contains feedback on the USP document grouped into these areas:

  • Protocol review
  • Reagents
  • Samples for study
  • Number of samples and statistical methods

It comments on issues such as the feasibility of testing the recommended matrix using four different recombinant reagents and four different lysate reagents, and that water post-deionization (low-purity) but before distillation/ultra-filtration (high-purity) is not representative of samples typically tested for bacterial endotoxins. It also questions whether industry will be able to provide known contaminated samples as these would be difficult to obtain and then compare.

BioPhorum supports the publication of a general pharmacopeial method that will enable the wider use of recombinant reagents in the BET method.

“BioPhorum has contributed to the USP’s paper by providing insightful comments on a more sustainable source and avoiding any animal-sourced material,” said Philippe Gadal, Regulatory Intelligence advisor at bioMérieux. “This will benefit patients and stakeholders alike.”

Industry feedback on USP Bioreactivity Draft Monographs

Bioreactivity is a mandatory test for plastics used in the composition of primary packaging for parenterals and implanted devices. It is typically tested in two ways – using an in vivo test where extracts from the plastic are injected into live animals (e.g., rabbits), or an in vitro test where extracts are exposed to cultured cells.

USP <87> describes in vitro tests, USP <88> in vivo tests, and USP <1031> provides the strategy for testing plastics either way or both ways depending on the risk to the patient.

USP is currently revising these three monographs to update the bioreactivity compendial tests and the decision-making process to ensure the safety of plastics used for the packaging or administration of pharmaceuticals. The USP has asked for industry comments.

Feedback on the draft monographs was provided by a team of 15 subject matter experts from BioPhorum’s Regulatory, Single-Use systems, Packaging and Medical Devices Teams and has been published in Industry Feedback on USP Bioreactivity Draft Monographs.

It contains feedback on the USP document grouped into strategy, application of the bioreactivity monographs to plastics used for manufacturing, and the use of resources.

It also comments on the potential in vitro tests that should be included in <87>, the removal of the implantation test and safety in <88>, the removal of Class I to VI from <88>, and the topics for omission or inclusion into the <1031> chapter outline.

At this point in the process, the industry’s feedback is high level as the team feels that further alignment to other industry standards, such as ISO 10993: Biological evaluation of medical devices, is required before this can be done effectively.

BioPhorum and the USP are fully aligned with the 3R principles (the ‘Replacement, Reduction and Refinement’ approach that aims for more humane animal research). The expert feedback provided in these documents aims to support the USP and, ultimately, produce documents that improve patient safety – but with adequate use of finite analytical resources, which would not be the case with divergent expectations.

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