Longer-term use of a drug that relieves withdrawal symptoms might help young people undergoing treatment for addiction to heroin or prescription painkillers like Oxycontin, U.S. researchers said on Tuesday.

Young addicts who took Reckitt Benckiser's drug Suboxone for 12 weeks were less likely to abuse drugs during treatment and stayed in treatment longer than those who underwent short-term detox and counseling, they said.

Dr. George Woody of the University of Pennsylvania in Philadelphia said many treatment programs in the United States and other countries favor shorter-term detoxification and counseling for young people addicted to the drugs called opioids, but said drug treatment might be a more effective option.

"There is a hesitation to use medication," said Woody, whose study appears in the Journal of the American Medical Association. The problem is that relapse rates in these programs are quite high, he said.

Suboxone, known generically as buprenorphine-naloxone, combines two drugs. Buprenorphine relieves withdrawal symptoms, while naloxone deters abuse by causing an opioid addict to experience rapid withdrawal symptoms if it is taken improperly, such as by injection.

The researchers studied 152 opioid addicts aged 15 to 21 for 12 weeks. Patients in the Suboxone group got the drug for nine weeks, and then started tapering off until they were on no drug by week 12.

The other group got a lower dose of the drug and were tapered off after two weeks. All got weekly individual and group counseling.

By week eight, 23 percent of people in the drug group had positive urine tests, compared with 54 percent who were off the drug.

"We found when they are on the drug as compared to when they were off, their opiate use was much less," Woody said in a telephone interview, noting that the study found no serious side effects in the group who stayed on the drug.

They found the youths who continued to take Suboxone were less likely to use opioids, cocaine and marijuana, to inject drugs, or drop out of treatment than those who received short-term detoxification and counseling.

Opioids include heroin, morphine and prescription pain killers such as Vicodin and Oxycontin.

"These findings should reassure and encourage providers who have been hesitant to offer extended Suboxone treatment to this population," Dr. Nora Volkow, director of the National Institute on Drug Abuse, part of the National Institutes of Health, said in a statement.

"They also highlight the need for longer-term studies to determine whether sustained treatment can improve outcomes."