About Animal Rule


The FDA Animal Efficacy Rule applies to the development of drugs and biologics to reduce or prevent serious or life-threatening conditions caused by exposure to toxic agents (chemical, biological, radiological, or nuclear substances), where human efficacy trials are not feasible or ethical.

FDA can rely on evidence from animal studies to provide substantial evidence of product effectiveness when:

  • There is a reasonably well-understood mechanism for the toxicity of the agent and its amelioration or prevention by the product;
  • The effect is demonstrated in either:
    • More than one animal species expected to react with a response predictive for humans; or
    • One well-characterized animal species model (adequately evaluated for its responsiveness in humans) for predicting the response in humans.
  • The animal study endpoint is clearly related to the desired benefit in humans; and
  • Data or information on the pharmaco-kinetics and pharmaco–dynamics of the product or other relevant data or information in animals or humans is sufficiently well understood to allow selection of an effective dose in humans, and it is therefore reasonable to expect the effectiveness of the product in animals to be a reliable indicator of its effectiveness in humans.