FDA Green-Lights New Drug Designed to Treat Inhalable Anthrax

A new drug that can treat airborne anthrax has been given the go-ahead.

The U.S. Food and Drug Administration announced Friday that they had approved an injection called raxibacumab, which is designed to treat the breathable form of the deadly bacterium Bacillus anthracis, more commonly known as anthrax.

According to the FDA, raxibacumab, a monoclonal antibody, works by neutralizing toxins produced by anthrax that can cause massive and irreversible tissue injury and death.

The active protein in the new anti-anthrax drug works a lot like a human antibody does in being able to identify and deactivate invading bacteria and viruses inside a host human body.

The approval marked a milestone for the FDA, as the new drug was the first monoclonal given the "green light" under the agency's "animal rule" which allows efficacy investigations via well-controlled animal studies in certain cases.

In the case of raxibacumab, the drug tested well in several studies in monkeys and rabbits that were infected with anthrax, before being tested safely on what the Associated Press reported were 326 humans.

As Med Page Today notes, scientists tested 180 rabbits infected with the drug in an 84-hour study. Roughly 42 percent, or 76, of those rabbits survived until the 84-hour mark. Of the ones that survived to that point, 82 percent receiving raxibacumab and the antibiotic levofloxacin (Levaquin) survived 28 days, while 65 percent survived by taking only levofloxacin.

Meanwhile, 64 percent of animals in the monkey study survived the study.

The federal agency, which has jurisdiction over approving pharmaceuticals for legal purchase in the U.S., gave the anthrax-fighting drug a fast track designation, meaning that raxibacumab is on track for a faster review that could get it developed and available for patients faster.

Anthrax has been a health threat that has been used in previous years against the U.S. as a terrorism tool. Shortly after the September 11 terrorist attacks in 2001, five people died after being exposed to anthrax spores found in letters mailed to the offices of news media and two U.S. senators.

The FDA granted the drug this expedited process as it demonstrated "the potential to fill an unmet medical need, has the potential to provide safe and effective treatment where no satisfactory alternative therapy exists."

"In addition to antibiotics, raxibacumab will be a useful treatment to have available should an anthrax bioterrorism event occur," Edward Cox, M.D., M.P.H, director of the Office of Antimicrobial Products in FDA's Center for Drug Evaluation and Research, said in a statement. "Although antibiotics are approved to prevent and treat anthrax infection, raxibacumab is the first approved agent that acts by neutralizing the toxins produced by B. anthracis."