WASHINGTON -- The Food and Drug Administration on Monday approveda Johnson & Johnson tuberculosis drug that is the first newmedicine to fight the deadly infection in more than four decades.

Theagency approved J&J's pill, Sirturo, for use with older drugs tofight a hard-to-treat strain of tuberculosis that has not responded toother medications. However, the agency cautioned that the drug carriesrisks of potentially deadly heart problems and should be prescribedcarefully by doctors.

Roughly one-third of the world's populationis estimated to be infected with the bacteria causing tuberculosis. Thedisease is rare in the U.S., but kills about 1.4 million people a yearworldwide. Of those, about 150,000 succumb to the increasingly commondrug-resistant forms of the disease. About 60% of all cases areconcentrated in China, India, Russia and Eastern Europe.

Sirturo,known chemically as bedaquiline, is the first medicine specificallydesigned for treating multidrug-resistant tuberculosis. That's a form ofthe disease that cannot be treated with at least two of the fourprimary antibiotics used for tuberculosis.

The standard drugs used to fight the disease were developed in the 1950s and 1960s.

"Theantibiotics used to treat it have been around for at least 40 years andso the bacterium has become more and more resistant to what we have,"said Chrispin Kambili, global medical affairs leader for J&J'sJanssen division.

The drug carries a boxed warning indicating thatit can interfere with the heart's electrical activity, potentiallyleading to fatal heart rhythms.

"Sirturo provides much-neededtreatment for patients who have don't have other therapeutic optionsavailable," said Edward Cox, director of the FDA's antibacterial drugsoffice. "However, because the drug also carries some significant risks,doctors should make sure they use it appropriately and only in patientswho don't have other treatment options."

Nine patients takingSirturo died in company testing compared with two patients taking aplacebo. Five of the deaths in the Sirturo group seemed to be related totuberculosis, but no explanation was apparent for the remaining four.

Despitethe deaths, the FDA approved the drug under its accelerated approvalprogram, which allows the agency to clear innovative drugs based onpromising preliminary results.

Last week, the consumer advocacy group Public Citizen criticized that approach, noting the drug's outstanding safety issues.

"Thefact that bedaquiline is part of a new class of drug means that anincreased level of scrutiny should be required for its approval," thegroup states. "But the FDA had not yet answered concerns related tounexplained increases in toxicity and death in patients getting thedrug."

The FDA said it approved the drug based on two mid-stagestudies enrolling 440 patients taking Sirturo. Both studies weredesigned to measure how long it takes patients to be free oftuberculosis.

Results from the first trial showed most patientstaking Sirturo plus older drugs were cured after 83 days, compared with125 days for those taking a placebo plus older drugs. The second studyshowed most Sirturo patients were cured after 57 days.