The FDA Animal Efficacy Rule (finalized May 2002) applies to development/testing of drugs / biologicals to reduce or prevent serious/life-threatening conditions caused by exposure to lethal /permanently disabling toxic agent (chemical, biological, radiological, or nuclear substances), where human efficacy trials are not feasible or ethical.

FDA can rely on evidence from animal studies

Animal testing

Animal testing, also known as animal experimentation, animal research, and in vivo testing, is the use of non-human animals in experiments. Worldwide it is estimated that the number of vertebrate animals—from zebrafish to non-human primates—ranges from the tens of millions to more than 100 million...

 to provide substantial evidence of product effectiveness when:

• 1: There is a reasonably well-understood mechanism for the toxicity of the agent and its amelioration or prevention by the product;

• 2: The effect is demonstrated in either:
  • 2.1: More than one animal species expected to react with a response predictive for humans; or
  • 2.2: One well-characterized animal species model (adequately evaluated for its responsiveness in humans) for predicting the response in humans.

• 3: The animal study endpoint
  Clinical endpoint
  In a clinical research trial, a clinical endpoint generally refers to occurrence of a disease, symptom, sign or laboratory abnormality that constitutes one of the target outcomes of the trial, but may also refer to any such disease or sign that strongly motivates the withdrawal of that individual...
  
   is clearly related to the desired benefit in humans; and

• 4: 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
  Effective dose
  Effective dose may refer to:*Effective dose the dose of pharmacologic agent which will have a therapeutic effect in some fraction of the population receiving the drug...
  
  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.