From the Guidelines
The rabbit pyrogen test is a method for detecting endotoxin by injecting a test substance into a rabbit and monitoring the animal's body temperature, with the occurrence of fever indicating the presence of endotoxin.
Key Characteristics of the Rabbit Pyrogen Test
- Principle: Injection of test substance into rabbits and monitoring of the animals’ body temperature
- Advantages: FDA-approved
- Disadvantages: Expensive, use of animals, not specific for endotoxin, not quantitative 1
Comparison with Other Methods
The rabbit pyrogen test is one of several methods for endotoxin detection, including the limulus amoebocyte lysate (LAL) assay, Endozyme, EndoLISA, monocyte activation test (MAT), and HEK-Blue hTLR4 assay.
- The LAL assay is often considered the standard method for endotoxin detection and is available in three variants: gel-clot, turbidimetric, and chromogenic 1
- Other methods, such as Endozyme and EndoLISA, offer alternatives to the LAL assay and the rabbit pyrogen test, but may also have limitations, such as interferences with nanomaterials 1
Clinical Relevance
The rabbit pyrogen test has been used for over 100 years and was approved by the FDA in 1943, but its use is limited by its disadvantages, including the use of animals and lack of specificity and quantitation 1
From the Research
Definition and Purpose of the Rabbit Pyrogen Test
- The rabbit pyrogen test is an in vivo test that measures the fever reaction as an endpoint to detect pyrogens in parenteral pharmaceuticals 2.
- The test is used to evaluate the safety of injectable products by detecting the presence of fever-inducing substances, such as endotoxins and non-endotoxins 3.
- The rabbit pyrogen test is considered the "gold standard" for medical device pyrogenicity testing, despite its limitations 4.
Limitations and Challenges of the Rabbit Pyrogen Test
- The test has limitations in detecting material-mediated pyrogens, which can cause a febrile response in humans 4.
- The test is not suitable for assessing the pyrogen content of certain vaccines, such as meningococcal OMV based vaccines, due to the high levels of endotoxin present in the vaccine 5.
- The test gives a qualitative rather than quantitative response, and the rabbit models are highly variable, making it ambiguous as a consistency test 5.
- There are differences in the experimental procedures and pyrogen result judgment algorithms (PRJAs) among various pharmacopeias, which can affect the results of the test 6.
Alternative Methods to the Rabbit Pyrogen Test
- The Monocyte Activation Test (MAT) is an in vitro test that can detect substances that activate human monocytes to release cytokines, and has the potential to replace the rabbit pyrogen test 2, 4, 3.
- The MAT is based on the human fever reaction and thus, most closely reflects the human response, and has been shown to have 100% sensitivity and approximately 85% specificity compared to the rabbit pyrogen test 3.