The Food and Drug Administration has approved Anthrasil, Anthrax Immune Globulin Intravenous (Human), for treatment of inhalational anthrax when used with appropriate antibacterial drugs.
Inhalational anthrax is caused by breathing in Bacillus anthracis spores, which can occur after exposure to infected animals or contaminated animal products, or as a result of an intentional release of spores. In a statement, Dr. Karen Midthun – director of the FDA’s Center for Biologics Evaluation and Research – explained that Anthrasil “will be stored in U.S. Strategic National Stockpile to facilitate its availability in response to an anthrax emergency.”
Anthrasil was purchased by the U.S. Department of Health & Human Services’ Biomedical Advanced Research and Development Authority (BARDA) in 2011, but because it was not approved, its use prior to FDA approval would have required an emergency use authorization from the FDA.
The efficacy of Anthrasil was studied in animals because it was not feasible or ethical to conduct adequately controlled efficacy studies in humans, the FDA said. Monkeys and rabbits were exposed to Bacillus anthracis spores, and subsequently given either Anthrasil or a placebo. The survival rate for monkeys given Anthrasil was between 36% and 70%, with a trend toward increased survival at higher doses of Anthrasil. None of the monkeys given placebo survived. Rabbits had a 26% survival rate when given the drug, compared to 2% of those given placebo. A separate study exposed rabbits to Bacillus anthracis and treated them with either antibiotics or a combination of antibiotics and Anthrasil; survival rates were 71% for those treated with the combination and 25% for those treated with antibiotics only.
Safety was tested in 74 healthy human volunteers and the most commonly reported side effects were headache, back pain, nausea, and pain and swelling at the infusion site.
Anthrasil is manufactured by Cangene Corporation, based in Winnipeg, Canada, which developed the drug in collaboration with BARDA.