"Studies conducted in St. Petersburg, Russia, for more than a decade have demonstrated the efficacy and safety of different naltrexone formulations (oral, implantable, injectable) for relapse prevention and maintenance of abstinence in detoxified opioid addicts. The positive results from different formulations seem related to two cultural factors. One is that relatives can be recruited to supervise daily dosing of the oral formulation. However, this advantage is decreasing as the addicted population ages. The second is that substitution therapy is not available; thus, naltrexone is the only effective medication available, which makes it easier to motivate patients to use it. Preliminary findings from studies of long-acting, slow-release formulations of naltrexone (implantable and injectable) suggest that they are more effective than the oral formulations and are likely to be important additions to current treatments. How they compare with maintenance treatment using methadone or buprenorphine in settings in which these three treatment options are available is a topic for future studies."

Source

Krupitsky, Evgeny, Zvartau, Edwin, and Woody, George, "Use of Naltrexone to Treat Opioid Addiction in a Country in Which Methadone and Buprenorphine Are Not Available," Curr Psychiatry Rep. 2010 October; 12(5): 448–453. doi:10.1007/s11920-010-0135-5.
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