A study in The Lancet has said that the drug buprenorphine is twice as effective as a rival treatment called naltrexone in motivating heroin patients stay off the drug.
The two drugs, along with a dummy pill called a placebo, were tested for 22 months among 126 patients in Malaysia who had emerged from a detoxification and counselling programme, it said.
Buprenorphine, which is marketed as Temgesic or Buprenex, was twice as effective as naltrexone (branded as Revia, Depade or Vivitrol) and the placebo in terms of days of abstinence from heroin and a full-fledged relapse to the narcotic.
Indeed, buprenorphine proved to be so superior that the trial was halted early, as it would have been unethical to continue it to its scheduled end.
The study, led by Yale University's Richard Schottenfeld, gives support for placing buprenorphine alongside methadone, and both of them over naltrexone, as pharmacological treatments for helping addicts stay off heroin.
The three drugs belong to a class called opioid antagonists.
These treatments are increasingly used to help ease heroin dependence but remain prohibited in some countries, amid suspicions that they are liable to be abused or simply substitute one addiction for another.
The study is important because it gives the first assessment of the relative effectiveness of two of the opioid antagonists.
Heroin and other illicit opiates were once a problem mainly confined to developed countries, but in the past few decades have spread to developing economies and nations of the former Soviet bloc.
China, India, Indonesia, Iran, Malaysia, Pakistan and Russia are among the countries where expansion of heroin use has risen fastest, according to a 2004 World Health Organisation (WHO) paper.