FDA Expands Indication of Moxifloxacin (Avelox) for Plague

Disclosures

May 08, 2015

The US Food and Drug Administration (FDA) today approved the antibiotic moxifloxacin (Avelox, Bayer Healthcare Pharmaceuticals) to treat two forms of plague, a rare but sometimes fatal bacterial infection that surfaced last year in Colorado and possibly spread through human-to-human contact, the agency announced.

Plague is caused by the bacteria Yersinia pestis, which authorities say could be used for bioterrorism. Humans can acquire the bacteria through bites from infected fleas, contact with infected animals or humans, or laboratory exposure. The FDA puts the annual number of plague cases worldwide at 1000 to 2000. The disease is more common in the tropics, the subtropics, and warmer regions of temperate countries, according to the World Health Organization. Untreated, plague has a mortality rate of 30% to 60%, but antibiotics can knock that down to 15%.

Last summer, four people in Colorado contracted plague, but survived after treatment. The Centers for Disease Control and Prevention (CDC) reported this April that the first person infected had acquired Y pestis from his dying pet dog. The three other individuals also had contact with the dog, but one of them appeared to have caught the bacteria instead from the dog's owner, the CDC said. The last case of human-to-human transmission of plague in the United States occurred in 1924, according to the CDC.

More recently, Madagascar experienced a plague outbreak that killed 71 people from September 2014 through mid-February.

The three most common forms of plague are bubonic plague, a lymph node infection; septicemic plague, a blood infection; and pneumonic plague, a lung infection that can cause death within 24 hours if left untreated. The FDA approved moxifloxacin for septicemic and pneumonic plague, but not for bubonic plague, an indication that Bayer Healthcare Pharmaceuticals did not apply for.

Clinicians also can prescribe moxifloxacin for adults to prevent plague.

Moxifloxacin joins an arsenal of antiplague drugs that also includes levofloxacin (Levaquin, Janssen Pharmaceuticals), streptomycin, doxycycline, and tetracycline.

Because it would not have been feasible or ethical to test moxifloxacin for plague in humans, the FDA based its approval on a study of 20 African green monkeys that were infected with Y pestis in a laboratory, the agency said. Ten of the monkeys received the drug for 10 days and all of them survived. Ten monkeys who received a placebo died.

Moxifloxacin, a fluoroquinolone, already is approved for treating adults with acute bacterial sinusitis, acute bacterial exacerbation of chronic bronchitis, community-acquired pneumonia, uncomplicated and complicated skin and skin structure infections, and complicated intra-abdominal infections. Its common adverse events include nausea, diarrhea, and headache. Other adverse events include allergic reactions, liver damage, abnormal heart rhythm, and neurological problems such as dizziness and confusion.

The drug carries a boxed warning about the increased risk for tendinitis and tendon rupture. It also states that physicians should avoid prescribing moxifloxacin for patients with myasthenia gravis because it can worsen muscle weakness.

"Given that plague is a very serious and often deadly condition, the benefit of Avelox for treating plague outweighs these potential risks," the FDA said in a news release.

More information about today's announcement is available on the FDA website.

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