(Feb. 13) - Methadone, a painkiller that has been used to treat heroin addicts for decades, has emerged as an increasingly popular and deadly street drug, joining narcotics such as Vicodin and OxyContin as frequently abused prescription drugs.

Fatal overdoses of methadone rose at a higher rate than those involving any other narcotic from 1999 through 2004, according to a recent study by the National Center for Health Statistics (NCHS). The number of deaths from methadone in 2004 (3,849) represented a 390% rise from 1999, the study said.

Methadone was cited in nearly 13% of all the overdose deaths reported in the USA in 2004, up from about 4% five years earlier. Among drugs cited in fatal overdoses, only cocaine kills more people than methadone.

The NCHS study - and reports from coroners nationwide that the trend is continuing - indicate that doctors' increasing tendency to prescribe methadone as a cheap alternative to addictive pain relievers such as OxyContin has made it easier for addicts to get methadone, the Drug Enforcement Administration's Denise Curry says.

"It's out there, it's available, and it can be dangerous," Curry says. Pharmacies report that methadone is among the most popular drugs stolen, along with Vicodin and OxyContin, she says.

At about $20 a pill on the black market and pennies a dose when prescribed, methadone is considerably cheaper than such opiates.

Methadone has long been viewed as a relatively safe and effective narcotic, in part because its effects are gradual and it can ease withdrawal symptoms for recovering heroin addicts.

However, it also is addictive, and drug addicts account for most methadone-related deaths, says Nicholas Reuter, a senior public health analyst at the Substance Abuse and Mental Health Services Administration.

Reuter says the problem is complicated by doctors who prescribe methadone incorrectly and patients who do not follow directions in taking it. On Nov. 26, the Food and Drug Administration warned doctors that "prescribing methadone is complex" because it eases pain up to six hours but can stay in the body 59 hours. Patients may want more before the dose wears off, the FDA warned.

"Methadone may build up in the body to a toxic level if it is taken too often, if the amount taken is too high, or if it is taken with certain other medications," the FDA said.

Authorities nationwide cite rising methadone fatalities:

-- Fatal drug overdoses in New Hampshire rose from 39 in 1995 to 105 in 2003, and chief state medical examiner Thomas Andrew determined that methadone was the key. In 2005, Andrew says, at least 52 of the 153 people who died from overdoses in the state had taken methadone. He suspects the trend continued in 2006.

-- Florida has had a "steady increase" in methadone deaths since 2001, says Jennifer Cook Pritt of the Department of Law Enforcement.

-- In West Virginia, where fatal methadone overdoses rose from 40 in 2001 to 116 in 2005, state legislators are holding hearings on a plan to limit the medical professionals who could prescribe the drug, says Del. Don Perdue, a Democrat  who leads the health committee in the House of Delegates.