The U.S. Food and Drug Administration approved the use of Anthrasil Tuesday for treating inhalational anthrax alongside antibacterial drugs, triggering a $7 million payment to Emergent BioSolutions under a Biomedical Advanced Research and Development Authority contract.
A rare disease, inhalational anthrax occurs after an individual is exposed to an infected animal or animal products that have been contaminated. Infection is also possible when anthrax spores are intentionally released, leading to the inhalation of Bacillus anthracis. After the bacterium enters the body, it replicates and produces toxins, causing massive, irreversible injury to tissues. Damage can also be so severe that an infection can be fatal.
Anthrasil's approval bolsters the United State's efforts at preparing for the possibility of an anthrax attack, adding to the number of drugs part of the U.S. Strategic National Stockpile. Anthrasil has been accessible prior to the FDA's approval but its use would warrant an emergency use authorization from the agency.
"Emergent is pleased to receive FDA approval of Anthrasil, the only FDA-approved polyclonal therapeutic for the treatment of anthrax disease," said Adam Havey, biodefense division president and executive vice president for Emergent BioSolutions.
A sterile solution, Anthrasil is produced from purified human immune globulin G that contains polyclonal antibodies targeting anthrax toxins created by Bacillus anthracis. The drug is made using plasma from healthy individuals that have been previously immunized with BioThrax, Emergent BioSolutions' anthrax vaccine. BioThrax is also the only vaccine licensed by the FDA to prevent anthrax disease.
Under a 2013 BARDA contract, Emergent BioSolutions continued to collect and store human plasma needed for potential production of Anthrasil. The inclusion of Anthrasil in the U.S. Department of Health and Human Services' anti-anthrax preparation was agreed upon in a BARDA contract awarded in 2005. Since then, the medication has been delivered and stored at the U.S. Strategic National Stockpile.
Anthrasil received approval based on the FDA's Animal Rule which stipulates that findings from adequate animal studies may be used to support a drug's efficacy when it is not ethical or feasible to conduct trials on humans. Emergent BioSolutions' inhalational anthrax treatment was tested on monkeys and rabbits instead. In both animals, Anthrasil proved to be effective in promoting survival compared to placebo.
After being proven effective, Anthrasil was tested for safety through 74 healthy volunteers. Common side effects reported include swelling, nausea, back pain, headaches and pain on the infusion site.
