Inhalational Anthrax Treatment Gets FDA Nod

The FDA today approved Emergent BioSolutions’ anthrax immune globulin intravenous (human) (Anthrasil) for the treatment of inhalational anthrax in combination with appropriate antibiotics.

Inhalational anthrax occurs when a patient inhales the spores of Bacillus anthracis, a bacterium that replicates in the body and produce toxins that can cause irreversible tissue injury and death.

In 2011, the US Department of Health and Human Services purchased Anthrasil, which is derived from the plasma of individuals vaccinated against anthrax, as an experimental drug for the US Strategic National Stockpile. Prior to today’s approval, the drug’s use would have required emergency authorization from the FDA.

“Today’s approval provides an important additional treatment to other FDA-approved therapies for inhalational anthrax, a life-threatening disease,” said Karen Midthun, MD, director of the FDA’s Center for Biologics Evaluation and Research, in a press release. “This product will be stored in US Strategic National Stockpile to facilitate its availability in response to an anthrax emergency.”

The FDA based its nod on a number of studies which evaluated the drug’s efficacy in animals. In 1 study, the survival rate of anthrax-infected monkeys treated with Anthrasil ranged from 36% to 70% while none of placebo-treated monkeys survived, with the research team observing increased survival at higher doses of the drug. The researchers of another study found that rabbits treated with a combination of Anthrasil and antibiotics experienced a 71% survival rate, compared with 25% survival in rabbits treated with antibiotics alone.

Under the FDA’s Animal Rule, which allows a drug’s approval to be supported by efficacy findings from animal studies when it is not feasible or ethical to conduct trials in humans, the agency determined that Anthrasil is reasonably likely to benefit anthrax-infected humans.

The product’s safety was tested in 74 healthy human patients, with the most commonly observed adverse events including headache, back pain, nausea, and infusion site pain and swelling.