The US Food and Drug Administration (FDA) and other government agencies around the world require testing for drugs and medical devices before they are marketed for human use. One of these requirements is testing for contamination by bacteria, viruses, fungi, and other fever-inducing agents – collectively known as pyrogens.

Advancement of Non-Animal Pyrogen Test Methods

To accelerate the adoption of non-animal pyrogen tests by government agencies and companies, in 2018, the Science Consortium and the NTP Interagency Center for the Evaluation of Alternative Toxicological Methods co-hosted a workshop on using the animal-free monocyte activation test (MAT) to meet pyrogen testing requirements for medical devices. As a result of this workshop, the Science Consortium is collaborating with companies and the FDA through the Medical Device Development Tools programme to gain the agency’s seal of approval for using the test with this class of products.

Test Methods

The two test methods that use animals – the rabbit pyrogen test (RPT) and the bacterial endotoxin test (BET) – have numerous scientific limitations. Animal-free methods that can replace these animal tests are available. For example, recombinant factor C (rFC) is a synthetic version of the BET that does not use horseshoe crabs. The MAT can be used to detect the full array of pyrogens, and because it is based on human biology, it can better predict the human response. This method uses donated human blood or cultured human blood cells, thereby harnessing the pyrogen detection system built by the human immune system.1,2

Regulatory Acceptance

While there has been progress in the development of pyrogen tests, widespread adoption of the rFC and the MAT by companies has been slow, largely because of a lack of international regulatory acceptance. Several government agencies allow for the use of the rFC and the MAT, and more agencies are in the process of adopting the use of these tests.

  • The European Pharmacopoeia includes both the rFC and the MAT,3–5 and in June 2021, the European Pharmacopoeia Commission stated its intention to end the use of rabbits in pyrogen tests within five years.
  • The US Pharmacopeia (USP) allows the use of replacements for the RPT and the BET, and, in 2020, the USP Convention announced plans to formally adopt text that would encourage the use of the rFC in place of the BET. While both the USP6 and the FDA have acknowledged the value of the rFC and the MAT and allow companies to use them under specific conditions, a formal Citizen Petition has been submitted asking the FDA to allow companies to use the rFC more broadly, based on a wide range of successful applications of this animal-free approach.
  • The Japanese Pharmacopoeia has proposed adding the rFC to its official text.

As government agencies continue to adopt stronger positions of support for the rFC and the MAT, acceptance of these methods will be advanced by companies using them in regulatory submissions.


1Hasiwa N, Daneshian M, Bruegger P, et al. Evidence for the detection of non-endotoxin pyrogens by the whole blood monocyte activation test. ALTEX. 2014;31(2):226. doi:10.14573/altex.2014.2.226.

2Hartung T. The human whole blood pyrogen test – lessons learned in twenty years. ALTEX. 2015;32(2):79-100. doi:10.14573/altex.1503241.

3European Directorate for the Quality of Medicines & HealthCare (EDQM). Recombinant factor C: new Ph. Eur. chapter available as of 1 July 2020. EDQM. Published 1 July 2020. Accessed 19 October 2021.

4EDQM. General Chapter 2.6.30. Monocyte Activation Test. Ph Eur. 2020;10.

5ECA Academy. EDQM announces revision of general chapter Monocyte Activation Test (2.6.30). ECA Foundation. Published 28 July 2016. Accessed 19 October 2021.

6US Pharmacopeia. Bacterial Endotoxins Test – Chapter 85. United States Pharmacop. 2012;37(85):1-5.