The recent headway of two treatments for addiction to heroin and other opiates represents a major advancement and has the potential to put opioid addiction therapy within the purview of primary care providers, according to several experts.
The approval in October of a new indication for an injectable, extended-release formulation of the opioid receptor antagonist naltrexone, marketed as Vivit-rol (Alkermes Inc.), allows for its use as a treatment for preventing relapses in people who have undergone opioid detoxification. Moreover, an implantable form of the opiate agonist buprenorphine, which delivers a continuous dose of medication for up to 6 months, showed promise in a recently published phase III study.
Both advances have the potential for broadening access to care and improving treatment compliance, according to Dr. Nora D. Volkow, a psychiatrist and the director of the National Institute on Drug Abuse (NIDA).
Ultimately, the treatment options could help improve outcomes for the more than 800,000 people in the United States who are believed to be addicted to heroin, and the 1.85 million who abuse or are dependent on opioid pain relievers, such as Oxycontin and Vicodin, Dr. Volkow said in an interview.
Dr. Volkow said she envisions an expanded role not just for psychiatrists and addiction medicine specialists, who have traditionally managed opioid-dependent patients, but also for primary care doctors and infectious disease specialists who could provide integrated care for heroin-addicted HIV patients.
Access to care for all people with opioid dependence would improve if more physicians adopt these new treatment options. Compliance also would improve, largely because both treatments involve extended dosing, Dr. Volkow said.
Older treatment options such as methadone and daily sublingual buprenorphine can be effective, particularly when combined with counseling. However, they require more frequent dosing, a daunting hurdle for patients whose ability to be compliant is easily derailed by the forces of craving and the risk of relapse. Diversion is an issue with sublingual buprenorphine. Many treatment centers reject the idea of using opiates, even synthetic ones, to treat opioid addiction.
Vivitrol, approved in 2006 for the treatment of alcohol dependence, is the first nonnarcotic, nonaddictive extended-release medication approved to treat opioid dependence. In a 6-month study of 250 patients, monthly intramuscular injection with the drug proved significantly more effective than placebo for preventing relapses: 36% of treated patients, compared with 23% of those on placebo, used no opioids between the 5th week and the end of the study, according to a statement released by the Food and Drug Administration following its approval of this new indication.
Importantly, all the patients in the trial were completing or had recently completed detoxification and were no longer physically dependent on opioids at baseline. Despite concerns that patients wouldn't return for repeat injections, Dr. Volkow said she was particularly encouraged to learn that patients did return routinely in the Russian studies on which the new Vivitrol approval was based.
"Patients were very compliant, which was not necessarily predictable," she explained. "That made me very excited about this particular medication."
NIDA is funding a study to replicate and expand on the Russian studies, to verify that U.S. patients would respond similarly. Investigators also plan to compare outcomes associated with Vivitrol vs. buprenorphine, she said.
In a phase III, randomized controlled study of 108 opioid addicts, implantable buprenorphine was associated with a 6-month significant reduction in drug use among 40% of patients, compared with 20% of those taking placebo.
About 60% of the treated participants completed the study without experiencing …