Anthrasil, Anthrax Immune Golbulin Intravenous (human), has been approved by the FDA for the treatment of patients with inhalational anthrax in combination with appropriate antibacterial drugs.
Inhalational anthrax is a rare disease that can occur after exposure to infected animals or contaminated animal products, or as a result of an intentional release of anthrax spores. It is caused by breathing in the spores of the bacterium Bacillus anthracis. When inhaled, anthrax bacteria replicates in the body and produces toxins that can cause massive and irreversible tissue injury and death.
Anthrasil is manufactured from the plasma of individuals vaccinated against anthrax. The plasma contains antibodies that neutralize toxins produced by the anthrax bacteria.
The efficacy of Anthrasil was studied in animals because it was not feasible or ethical to conduct adequately controlled efficacy studies in humans. Rabbits and monkeys were exposed to a lethal aerosolized dose of B. anthracis spores, then treated with Anthrasil or a placebo, and evaluated for survival. Survival in anthrax-infected monkeys treated with Anthrasil ranged from 36 to 70 percent compared to 0 percent survival in the placebo group with a trend toward increased survival at higher doses of Anthrasil. Rabbits treated with a moderate dose of Anthrasil after infection exhibited 26 percent survival compared to 2 percent survival in the placebo group. Another study in rabbits showed that a combination of Anthrasil and antibiotics resulted in 71 percent survival compared to 25 percent survival in animals treated with antibiotics alone.
The results of studies in research animals provided sufficient evidence that Anthrasil is reasonably likely to benefit humans with inhalational anthrax. The FDA’s Animal Rule allows efficacy findings from adequate and well-controlled animal studies to support FDA approval when it is not feasible or ethical to conduct trials in humans.
The safety of the product was tested in 74 healthy human volunteers. The most commonly observed side effects were headache, back pain, nausea and infusion site pain and swelling.
The product is manufactured by Cangene Corporation, based in Winnipeg, Canada. It was developed with support from BARDA within HHS’ Office of the Assistant Secretary for Preparedness and Response.