Gary and Ruth Pettijohn, of Batesville, Ind., hold a photo of their daughter, Kristen, who died after being prescribed a powerful antibiotic called Avelox. RANDY AMICK, KRT

The drug Kristen Pettijohn took was called Avelox. It's part of a family of antibiotics called fluoroquinolones.

Those powerful but risky drugs are intended for patients who are fighting particular bacterial bugs. But they're widely prescribed off-label for less serious illnesses, sometimes even to treat viruses, which can't be killed by antibiotics.

A study this year funded by the National Institutes of Health reviewed 100 emergency room prescriptions for fluoroquinolones and found that only 19 were written for appropriate conditions and only one was given in the correct dose and for the proper duration.

The FDA long has been aware of the possibility that Avelox could be misused.

Just before it approved Avelox in 1999, a member of the agency's expert review panel — Robert Danner, a critical care expert at the NIH — offered a warning: "This is exactly the kind of place that you get into trouble. … I am absolutely convinced that the drug will be used differently once it's marketed frequently."

Avelox was approved, however, and marketed hard by Bayer Corp. In 1999 and 2001, the FDA admonished company officials for encouraging unapproved uses.

This past May, Pettijohn, a gregarious 23-year-old nursing student from Batesville, Ind., who recently had gotten engaged, picked up the persistent cold that had been running through her family. "Her version was a little worse than ours," said her father, Gary Pettijohn. "I would say it was moderate at best."

Early in the morning of May 15, Pettijohn's mother took her to an emergency room. Going there, Pettijohn told her mom, would be quicker than waiting for an appointment with their family physician.

Forty-two minutes later, Pettijohn was on her way to the drugstore. The doctor had diagnosed her with acute bronchitis and prescribed Avelox. The potent antibiotic's label says it's approved for cases of chronic, or long-term, bronchitis, and only after blood tests have been taken to identify the bacteria causing the problem. Her medical records show no blood work was done.

That was a Thursday. By Sunday, Pettijohn was nauseated and suffering abdominal pain. Her mother packed a plastic bag with the remaining Avelox pills and took her to the hospital.

Over the next five days, Pettijohn was incoherent. She had a burning rash and her skin began peeling off. She slipped into a coma, resting on an air bed, totally wrapped as though she were a severe burn patient.

By Wednesday, a doctor approached Gary and Ruth Pettijohn.

"Our problem just got twice as difficult," he said. "She has two life-threatening conditions simultaneously."

Pettijohn's liver was in full failure, and she was experiencing a form of Stevens-Johnson syndrome, a rare and extreme drug reaction mentioned on the Avelox label.

She had a liver transplant on Friday. The doctors reported that her old liver had turned to mush and fallen apart in their hands.

Soon after the operation, Pettijohn had a heart attack, then another. Her death certificate cited Avelox as the prime contributing factor in her death.

The hospital had no comment about her death. Bayer had no comment beyond saying the death "was promptly and accurately reported to the FDA," and that it thinks its antibiotic should be prescribed only for approved conditions.