Federal regulators said Friday they are reviewing the effects of a novel antibiotic that has resulted in three cases of severe liver problems, including one that has resulted in death. They are looking at a number of U.S. cases involving the drug and are also consulting with regulators overseas.

A patient at Carolinas Medical Center in Charlotte, N.C. died after taking Ketek (generic name: telithromycin), according to the Associated Press. Ketek is an FDA-approved antibiotic used to treat bacterial infections from bronchitis to pneumonia.

Dr. John Hanson, who works in the liver transplant center at Carolinas Medical Center, said that the cases did warrant an investigation into whether the patient's liver problems were linked with the drug.

Researchers have said it hasn't been proven whether or not the problems have been caused by the drug. The cases will appear in a research paper that will publish in the Annals of Internal Medicine in March.

The drug is manufactured by Sanofi-Aventis. A spokeswoman for the company did not return calls from AP Friday.