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Old TB Drug Gets a Second Look

There's more good news about tuberculosis treatment. Recently we reported that researchers from the Johns Hopkins University were testing a new drug, moxifloxacin, in Brazil and finding it works well against TB. Now another Hopkins researcher has revived the use of an older TB drug, and he's finding it works well when administered differently than in the past. Rose Hoban has details.

Dr. Eric Nuermberger says rifapentine was developed in the 1990s to be a long-acting drug that could be given once or twice a week. "Rifapentine has a very long half-life, so it sticks around in the body for a long time and the intent was that this drug might allow TB treatment to be given once a week instead of every day, or three times a week as is commonly done." But it turned out that rifapentine didn't work so well when given only once or twice a week. So the drug company stopped making and marketing the drug.

However, Nuermberger decided to give rifapentine a second look. Instead of the recommended treatment protocol, he gave it to mice more frequently, and at higher doses. "And when we did that," he reports, "we found that we could cut the duration of treatment in half, or make it even shorter than half the usual six-month duration of therapy in a mouse model."

He says that dramatic shortening of the duration of therapy was a pleasant surprise. "While we predicted it would be better [than if given the original way], we just didn't know how much better. And it was more effective than we had expected."

Because the drug was already developed and tested in humans in the 1990s, Nuermberger says clinical trials using the new dosing regimen could be expedited. Researchers will simply need to observe patients taking rifapentine at these higher doses to make sure there are no side effects.

But Nuermberger says while new uses for rifapentine are exciting, there is still a desperate need for new kinds of drugs to fight TB. "It's often underappreciated, but TB is a major problem. It is the single greatest killer among bacterial diseases in the world," he observes. "It kills nearly 2 million people a year, a fact that is not really well-appreciated in well-to-do countries."

Nuermberger published his results in the on-line journal PLoS Medicine.