Anthrax: Developing Drugs for Prophylaxis of Inhalational Anthrax, Guidance for Industry [open pdf - 116KB]
"The purpose of this guidance is to assist sponsors in the development of drugs for the indication of prophylaxis of inhalational anthrax in persons who have or may have inhaled aerosolized 'Bacillus anthracis' spores but who have not yet manifested clinical evidence of disease. The indication also applies to persons with anticipated exposure to 'B. anthracis' spores (e.g., first responders for anthrax incidents); in such cases, initiation of antibacterial therapy would begin immediately before entering the 'B. anthracis'-contaminated environment. [...] This guidance clarifies that drugs developed for the prophylaxis of inhalational anthrax are to be considered for approval under the animal rule. This guidance does not contain discussion of the general issues of statistical analysis or clinical trial design."
Food and Drug Administration: https://www.fda.gov/