Naltrexone, Buprenorphine-Naloxone Found Equally Effective in OUD Patients Who Initiate Treatment

Extended-release naltrexone and sublingual buprenorphine-naloxone appear to be equally safe and effective at preventing opioid relapse in patients with opioid use disorder (OUD). However, it can be harder to initiate patients actively using opioids on naltrexone (due to required detox period) than buprenorphine-naloxone. These two findings were reported in a study published yesterday in The Lancet.

“Both medications are effective treatments for opioid use disorders versus counseling-only approaches or compared to placebo. What is now clear is how similar the outcomes are for those initiating treatment with either medication,” Joshua D. Lee, M.D., M.Sc., of NYU School of Medicine said in a press release. “Patients wanting naltrexone but who are unable to complete detox should be encouraged to start an agonist-based treatment like buprenorphine.”

Naltrexone (an opioid μ-receptor antagonist) differs from buprenorphine both in terms of induction and ongoing care. The medication cannot be initiated until patients are fully detoxified without risking precipitated withdrawal, but once initiated, naltrexone produces no opioid-like effects and no physiological dependence. In contrast, buprenorphine (a partial agonist) can be initiated as soon as patients are in mild-to-moderate withdrawal. Unlike naltrexone, buprenorphine maintains physiological opioid dependence, and withdrawal is likely to occur on discontinuation.

Lee and colleagues randomly assigned 570 patients with OUD to receive monthly injections of extended-release naltrexone (brand name Vivitrol) or daily buprenorphine-naloxone (brand name Suboxone) for 24 weeks. Study participants were 18 years or older and had used non-prescribed opioids in the past 30 days. Unlike patients in the buprenorphine-naloxone group, who received medication shortly after randomization, those assigned to naltrexone had to complete detoxification before receiving the first injection of medication. Detoxification was defined as not using an opioid for three or more days, having urine that tested negative for opioids, and having a negative naloxone challenge.

As expected, fewer patients successfully initiated naltrexone compared with buprenorphine/naloxone (72% versus 94%). Of the 474 patients who successfully began treatment, the proportion of opioid-relapse events over the course of the study was similar (52% for the naltrexone group versus 56% for the buprenorphine/naloxone group). The proportion of participants reporting adverse events and serious adverse events did not differ between the groups, with the exception of reactions at the injection site of naltrexone, all of which were of minor to moderate severity.

“Studies show that people with opioid dependence who follow detoxification with no medication are very likely to return to drug use, yet many treatment programs have been slow to accept medications that have proven to be safe and effective,” Nora D. Volkow, M.D., director of the National Institute on Drug Abuse, said in a press release. “These findings should encourage clinicians to use medication protocols, and these important results come at a time when communities are struggling to link a growing number of patients with the most effective individualized treatment.”

For related information, see the Psychiatric News PsychoPharm article “Psychiatrists Discuss Risks, Benefits of Medications for Opioid Use Disorder.”

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Extended-Release Naltrexone as Effective, Safe as Buprenorphine-Naloxone, Study Finds

Treatment with extended-release naltrexone appears to be as safe and effective as daily oral buprenorphine-naloxone in maintaining short-term abstinence from heroin and other illicit substances in newly detoxified individuals, according to a study in JAMA Psychiatry. The findings were based on a 12-week, multicenter, outpatient, open-label trial conducted at five addiction clinics in Norway. 

After detoxification, 159 opioid-dependent adults (according to DSM-4) were randomly assigned to either daily oral flexible dose buprenorphine-naloxone (4 mg/d to 24 mg/d) or extended-release naltrexone hydrochloride (380 mg, administered intramuscularly every fourth week) for 12 weeks. At the start of the trial and again at 4, 8, and 12 weeks, patients underwent a structured interview using the European version of the Addiction Severity Index covering drug use, physical and mental health, work, education, and criminal activity. 

Treatment with extended-release naltrexone was found to be as effective as buprenorphine-naloxone at maintaining retention in treatment (mean number of days until dropout from study medication: 69.3 days and 63.7 days of 84 days, respectively). Additionally, there were no significant differences between the treatment groups in the proportion of opioid-negative urine drug tests, or pattern of use of amphetamine, cocaine, alcohol, cannabis, or injecting drugs. 

Participants receiving extended-release naltrexone reported significantly less heroin craving and thoughts about heroin than did buprenorphine-naloxone participants, as well as greater treatment satisfaction. Individuals in the extended-release naltrexone group reported more adverse events than those in the buprenorphine-naloxone group (49 [69.0%] vs 25 [34.7%]). Some of these events were related to induced or experienced withdrawal symptoms, such as nausea, chills, shivering, diarrhea, and sneezing, the authors reported.

“Maintaining short-term opioid abstinence with extended-release naltrexone should be considered an equal treatment alternative to buprenorphine-naloxone as medication-assisted treatment for opioid-dependent individuals,” Lars Tanum, M.D., D.M.Sc., of the University of Oslo in Norway and colleagues wrote.

For related information, see the Psychiatric News article “Low-Dose Naltrexone May Mitigate Severity of Opioid Withdrawal During Detox" and the Psychiatric Services article “Fentanyl and the Evolving Opioid Epidemic: What Strategies Should Policy Makers Consider?.”

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