Sidebar: The Science on Naltrexone

Aug 5, 2015


  When the Department of Corrections begins offering naltrexone to male inmates sometime this fall, it will put New Hampshire among the more than 20 states that use the drug to treat incarcerated addicts.

New Hampshire, however, will launch the program using the oral version of naltrexone, which studies show faces more barriers to success than the extended-release injections used in other prisons and jails across the country.

Federal regulators approved naltrexone as a daily treatment for heroin addiction in 1984. Even then, clinical studies had identified a significant hurdle: Only a small percentage of patients who were “more motivated and emotionally stable” were likely to comply with the treatment.

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That's because, unlike methadone – at the time, the only other medication-assisted treatment for opioid addiction – naltrexone can’t get you high and, in fact, blocks the euphoric effects of opioids. Many, if not most, study participants therefore found it too convenient to skip a dose in order to use opioids.

Researchers also found that because naltrexone is non-addictive, patients could stop treatment without experiencing withdrawal. One more potential barrier identified early on was that many addicts are unable or unwilling to remain opioid-free for at least a week, which is necessary before beginning treatment.

As one study in 1984 concluded, "Those with stable family relationships, good jobs, minimal antisocial behavior, and low drug-craving before beginning a course of naltrexone appear to benefit most from the treatment. Rates of retention improve when naltrexone is used within a comprehensive rehabilitation program."  

Since then, dozens of studies have shared a similar conclusion: The drug works best in patients who are receiving behavioral therapy and other support services. Other studies suggest that those who have the most to lose by returning to opioid use – for instance, physicians, lawyers and other professionals who require a license - were also more likely to complete treatment.

Studies involving oral naltrexone use by opioid-dependent offenders – presumably a motivated group – support some of those findings, while producing mixed results.

A study published in 1997 involved 51 federal probationers. After six months, probationers – who met weekly with probation officers - given oral naltrexone had a re-incarceration rate of 26 percent, less than half that of a control group that received therapy only.

A second study, conducted by the same team of researchers, involved 111 addicts under legal supervision that included an alternative sentencing program and a drug court. While two-thirds of participants dropped out of the study, there was moderate success among the drug-court participants, who were subject to urine tests three times a week.

In 2010, the Food & Drug Administration approved an extended-release form of naltrexone, called Vivitrol, that is administered via injection once a month. Several studies have since shown it to be more effective at keeping addicts in treatment and preventing relapse.

Results of a clinical trial involving 250 patients, published in 2010, reported that median treatment time was 170 days for those treated with Vivitrol, compared to 96 in the group receiving a placebo. More than half the participants completed the study, and nearly 36 percent remained opioid free throughout, compared to 23 percent for the placebo group.

More recently, researchers at the NYU School of Medicine reported that injectable naltrexone was associated with much lower rates of relapse among men released from New York City jails than probationers who received no treatment.

Meanwhile, the research continues. The University of Pennsylvania has received a $2 million grant to determine if injectable naltrexone can reduce relapse rates among parolees in Philadelphia in the first three moths after release.  

The New Hampshire pilot program will begin with oral naltrexone largely because of budget considerations. The pill form will cost about $18 per month per patient, according to the state Department of Corrections, compared to $1,200 a month for each patient who receives injections.

In an email, Helen Hanks, assistant commissioner at the Department of Corrections, said the protocol is subject to change. She said, the agency is developing clinical guidelines that will include both the oral and injectable versions of the drug.