Gap Acute - 7: What are the most effective biomedical or dietary countermeasures to mitigate acute radiation risks?
Last Published:  07/31/18 09:30:04 AM (Central)
Responsible Element: Space Radiation (SR)
Status: Open

Initial State of Gap:

Medical countermeasures (MCMs) under development for use in clinical practice and against radiological threats are expected to provide risk reduction for low-LET radiation and SPE radiation delivered at high doses and dose rates.  Common over-the-counter medications and regularly prescribed pharmaceuticals for anti-nausea and diarrhea are expected to ameliorate symptoms associated with prodromal syndrome.


Ground-based research has resulted in preliminary evidence indicating that pharmaceutical agents developed for high dose gamma radiation may translate as medical countermeasures for hematopoietic acute radiation syndrome (H-ARS) due to SPE. Ground-based research using animal models to test medical countermeasures has provided additional evidence of risk reduction for H-ARS from solar particle event exposures using simulated SPE radiation and from successful studies with gamma exposure.  Additional studies in accordance with the FDA Animal Rule to validate the efficacy in a SPE-like environment will provide a greater level of confidence in countermeasure efficacy in humans.

Medical countermeasures for consideration will need to meet the requirements of the FDA Animal Rule to demonstrate safety and efficacy when human studies are not feasible.

Under the FDA Animal Rule:

The Animal Rule states that FDA will rely on evidence from animal studies to provide substantial evidence of effectiveness only when all of the following four criteria, quoted below, are met:

1. There is a reasonably well-understood pathophysiological mechanism of the toxicity of the substance and its prevention or substantial reduction by the product;

2. The effect is demonstrated in more than one animal species expected to react with a response predictive for humans, unless the effect is demonstrated in a single animal species that represents a sufficiently well-characterized animal model for predicting the response in humans;

3. The animal study endpoint is clearly related to the desired benefit in humans, generally the enhancement of survival or prevention of major morbidity; and

4. The data or information on the kinetics and pharmacodynamics of the product or other relevant data or information, in animals and humans, allows selection of an effective dose in humans.

If all of these criteria are met, it is reasonable to expect the efficacy of the drug in animals to be a reliable indicator of its effectiveness in humans.

Literature surveillance and technology watch activities will continue to identify new countermeasure drugs. Clinically-proven therapies or those currently being developed by the Biomedical Advanced Research and Development Authority (BARDA) and the National Institute of Health National Institute of Allergy and Infectious Diseases (NIH/NIAID) against acute effects from low-LET radiation exposure, as a result of nuclear disasters, may show effectiveness in the space environment. Chemopreventive agents being developed by the NIH National Cancer Institute (NIH/NCI) and tested in clinical trials may serve as candidates for radioprotection. Participation in multi-agency meetings and working groups will improve tech watch activities and allow for NASA to be aware of early stage product developments. 


Target for Closure
  • Identification and evaluation of select medical countermeasures to mitigate effects of acute radiation exposure.
  • Determine administration protocol for medical countermeasures.
  • Validate countermeasures to protect against H-ARS using space relevant radiation exposures and in accordance with the FDA Animal Rule.
Risk Risk of Acute Radiation Syndromes Due to Solar Particle Events (SPEs)
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