Does anthrax antitoxin therapy have a role in the treatment of inhalational anthrax?

PURPOSE OF REVIEW: Inhalational anthrax is a rare disease and Bacillus anthracis is a likely pathogen to be used in a biological attack. The lack of clinical experience with anthrax has led experts to develop treatment guidelines. These guidelines recommend anthrax antitoxin to be used in conjunction with antibiotics for the treatment of patients with systemic anthrax infection, yet there is still a lack of human or animal data to support this recommendation.

RECENT FINDINGS: The U.S. Food and Drug Administration-approved anthrax antitoxins in 2012, 2015, and 2016. These products have been stockpiled for use in a public health emergency. Although efficacy is high when given early, their efficacy diminishes quickly when given after the development of bacteremia. Animal studies showing a significant incremental benefit of antitoxin therapy when combined with antibiotic therapy were not required by the U.S. Food and Drug Administration for product approval.

SUMMARY: There is no conclusive evidence demonstrating that anthrax antitoxin therapy, when combined with a therapeutic course of antibiotics provides a survival benefit in inhalational anthrax. Additional research is needed in improved anthrax-antitoxin therapies, novel small molecule toxin inhibitors that act intracellularly, and studies of supportive care such as hemodynamic and ventilatory support, to improve the survival for inhalational anthrax patients and help mitigate the threat caused by the misuse of B. anthracis.