When determining a test for pyrogens and bacterial endotoxin, there are many regulations, needs, limitations, and techniques to consider. The original pyrogen test, the Rabbit Pyrogen Test (RPT; USP , formerly EP 2.6.8, and JP 4.04) and the original endotoxin test, the Bacterial Endotoxin Test (BET; USP , EP 2.6.14, and JP 4.01) served, and continue to serve, the quality control needs of pyrogen-free injectable pharmaceuticals, medical devices, accessory items. These will be referred to as “traditional” tests.
The next generation of pyrogen and endotoxin tests fulfil the need for sustainable, in-vitro, and animal-free tests solutions. These currently include the Monocyte Activation Test (MAT) (EP 2.6.30) for pyrogens, recombinant Factor C (rFC; EP 2.6.32 and USP ) for endotoxins, and recombinant cascade reagent (rCR; USP ) for endotoxins. These will be referred to as “new generation” tests.
When choosing the appropriate test method, several factors must be considered in choosing a next generation test method to replace a traditional method. These include pharmacopeial acceptance, the need for endotoxin-specific or general pyrogen testing, time of test and variability considerations, and interference considerations.
Firstly, it must be pointed out that there are advantages to the traditional tests. These tests are well-established, compendial, and harmonised across the pharmacopeia. This year, the RPT is being phased out in the European Pharmacopoeia, but it is still de facto international standard for pyrogens. Additionally, as an in-vivo test, the RPT has no need for considerations of interference as pyrogenicity is being directly measured. Finally, as new technologies, the new generation tests do not have universal acceptance in the pharmacopeia or harmonisation. Depending on the client’s location and product distribution, the best recommended method may vary. For example, the rCR reagent virtually replicates the traditional BET method. In the US, this reagent is now compendial and so provides an excellent new generation testing method. However, in locations where this is not published, the path to adoption is currently challenging. These factors are valid concerns, but they can be overcome by adopting the new generation tests.
