The U.S. Food and Drug Administration issued a strong advisory this week for methadone, a commonly prescribed pain medicine, warning patients and doctors that the drug can kill.

The alert was provoked by reports of overdose deaths among patients who took the medicine to combat chronic pain, the FDA release said.

In some patients, particularly new users or those switching from another narcotic pain medicine, methadone can slow breathing to a stop. The FDA warned that it also can cause dangerous changes in heartbeat.

Methadone, invented in Germany in the 1930s, was used mostly over the past 50 years as a safe, effective way to wean addicts off heroin. In the 1990s, many doctors turned to this standby painkiller after recognizing the dangerous high that its narcotic cousin OxyContin was causing. Doctors say it was a superior alternative: cheap and not likely to cause a high as other narcotic painkillers do.

But the FDA warns that methadone is tricky. Patients suffering from acute pain might be inclined to pop another pill while the medication is still in their system, creating a toxic buildup, researchers say.

"This really gives physicians the opportunity to recognize how important their role is," said Kay Sanford, an epidemiologist with the state Division of Public Health who has studied the sharp spike in methadone overdoses in North Carolina. "I don't think there's been recognition among physicians of their role in the increase of methadone-related deaths."

Problem surfaces

Public health officials discovered the problem with methadone in 2002 when they noticed a spike in accidental overdoses. From 2000 through 2004, methadone caused or contributed to the deaths of 817 North Carolinians.

A News & Observer analysis in March found that methadone was particularly deadly among teens. It accounted for three-quarters of all accidental overdoses in teens from 2002 through 2004.

In most of these deadly cases, methadone got into the hands of someone who hadn't been screened by a doctor. Methadone, like many pain pills, is swapped or sold on the black market or handed out by legitimate users to someone in pain.

The FDA also drafted a patient information sheet to accompany methadone prescriptions. It, too, warns patients of the deadly side effects and urges them to guard their pill bottles.

Other drugs risky too

Some doctors who treat chronic pain fear that methadone is being singled out unfairly, which could have a chilling effect on doctors willing to help these patients. They also worry that the added scrutiny of methadone will cause doctors to switch to other narcotics with a host of other potential harms.

"Methadone shouldn't be demonized in isolation," said Paul Chelminski, a UNC-Chapel Hill internist who treats patients for chronic pain and teaches other doctors how to carefully monitor narcotic pain medicines. "It's just the most conspicuous canary in the coal mine right now."