The U.S. Food and Drug Administration has approved Anthrasil (Anthrax Immune Globulin Intravenous) to treat patients suffering from inhalation anthrax in combination with other antibacterial drugs.
Inhalation anthrax is usually transmitted through infected animals, animal products, or the release of bacterium Bacillus anthracis spores, the FDA reported. The inhaled toxin can lead to massive tissue damage, resulting in serious injury and death.
The new treatment is manufactured from the plasma of individuals already vaccinated against the disease. This plasma contains antibodies that can fight the toxins produced by the dangerous bacteria.
"Today's approval provides an important additional treatment to other FDA-approved therapies for inhalational anthrax, a life-threatening disease," said Karen Midthun, director of the FDA's Center for Biologics Evaluation and Research. "This product will be stored in U.S. Strategic National Stockpile to facilitate its availability in response to an anthrax emergency."
Anthrasil was tested on animals due to practicality and ethical issues associated with its study in humans. Both rabbits and monkeys were exposed to lethal doses of the anthrax spores and then treated with Anthrasil or a placebo. The survival rate of the monkeys treated with Anthrasil proved to be between 36 and 70 percent, compared with 0 percent survival rate in those treated with the placebo. Rabbits treated with the new drug had a 26 percent survival rate, compared with only 2 percent in the placebo group. A combination of antibiotics and Anthrasil created a 71 percent survival rate among rabbits, compared with 25 percent of those 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 FDA stated.
The safety of Anthrasil was also tested in 74 healthy human volunteers. The most common observed side effects were "headache, back pain, nausea and infusion site pain and swelling."
