The FDA announced recently that it has approved the controversial antibiotic Levaquin for expanded use in battling the pneumonic plague should it be used in a bioterrorist attack. This is despite the fact that it rarely invokes the “animal efficacy rule.” The pneumonic plague is characterized by a lung infection that is similar to that which occurs with pneumonia.

What makes this new FDA approval for Levaquin use so interesting is that the drug currently holds a black box warning due to the tendon ruptures that have been linked to it. As for the drug’s newest approval in treating the pneumonic plague, FDA officials have invoked the animal efficacy rule, allowing proof to support the fact that a drug can be approved for human use on the basis that it isn’t harmful to animals as shown in clinical studies. This provides a pathway in the cases of ethical dilemmas that prevent testing the drugs on humans. For example, since the plague is such a rare disease, researchers can’t test Levaquin’s efficacy in people, so animal testing is all that can be provided in its place.

In this case, Levaquin was approved on the basis that the drug proved effective in treating some African green monkeys that had the plague. Levaquin’s expanded use allows the antibiotic to be used as a treatment for people who have the pneumonic plague; it will also lower people’s chances being exposed to the bacterium that causes the disease in the first place.

With Levaquin being listed as a potential treatment for the plague, some people may be concerned about the very real risks of people suffering from tendon ruptures and rotator cuff tears that have been proven to be caused by the drug. With this in mind, doctors may face more challenges in knowing just how to treat patients with the plague. Levaquin’s dangers are not a secret, but who knows what will be agreed to when someone hears that they have the plague. Only time will tell how this one works out.