Risk of Relapse Among Opioid-Dependent Patients Treated With Extended-Release Naltrexone or Buprenorphine-Naloxone: A Randomized Clinical Trial

BACKGROUND AND OBJECTIVES

Compare the risk of relapse to heroin and other illicit opioids among opioid-dependent patients receiving treatment with extended-release naltrexone (XR-NTX) or buprenorphine-naloxone (BP-NLX).

METHODS

Re-analyzed data from a 12-week multicenter, open-label, randomized treatment study with a subsequent 36-week open-label follow-up study. All patients, N = 143, had completed detoxification and received at least one dose of study medication.

RESULTS

Of 143 patients (72% men), mean age 36 years, 71 received XR-NTX and 72 BP-NLX. The risk of first relapse and the risk of any relapse to heroin and other illicit opioids were both significantly lower in the XR-NTX group compared with the BP-NLX group (hazard ratio [HR], 0.46; 95% confidence interval [CI], 0.28-0.76; P = .002, and HR, 0.11; 95% CI, 0.04-0.29; P < .001, respectively) and (HR, 0.15; 95% CI, 0.09-0.27; P < .001 and HR, 0.05; 95% CI, 0.03-0.09; P < .001, respectively). There was a stable low risk of relapse among participants receiving XR-NTX in the follow-up.

DISCUSSION AND CONCLUSIONS

Compared to BP-NLX, patients on XR-NTX had a substantially reduced risk of relapse to illicit opioids and showed a stable low risk of relapse over time in longer-term treatment.

SCIENTIFIC SIGNIFICANCE

Our data support XR-NTX as a first-line treatment option for patients with opioid addiction both in short and longer-term treatment. This is the first European study showing that XR-NTX significantly reduces the risk of first and any relapse to heroin use in opioid-dependent patients compared to BP-NLX. Our data contradict previous data from the X:BOT study, showing no significant difference in relapse risk between the groups in a 6-month randomised controlled trial. (© 2021 Authors. The American Journal on Addictions published by Wiley Periodicals LLC on behalf of The American Academy of Addiction Psychiatry). (Am J Addict 2021;30:451-458).

Availability of Extended-Release Naltrexone May Increase the Number of Opioid-Dependent Individuals in Treatment: Extension of a Randomized Clinical Trial

BACKGROUND AND OBJECTIVE

Opioid maintenance treatment (OMT) is highly available in Norway, but only 50% of opioid-dependent individuals are enrolled in such programs. This study was aimed at examining if availability of extended-release naltrexone (XR-NTX) could attract individuals who for different reasons were not enrolled in an OMT program.

METHODS

In a Norwegian clinical study, n = 117 opioid-dependent adults volunteered to receive XR-NTX in a 9-month period, as an extension of a previous randomized clinical trial.

RESULTS

Before study inclusion, 40.2% (n = 47) of the study participants were not enrolled in OMT while the remainder were recruited from OMT. Participants not enrolled in OMT displayed more ongoing severe addiction-related problems such as heroin use (p = 0.002), but displayed a higher retention in treatment in the 9-month extension study (p = 0.048 for log-rank test) than participants enrolled in OMT.

CONCLUSION

Availability of XR-NTX attracted opioid-dependent individuals not previously enrolled in OMT. While OMT may be perceived as a burden with regard to daily intake and control measures, one-monthly injections with XR-NTX may be perceived favourable, offering more freedom to the patients, not having addictive properties, and potentially reducing heroin craving. We suggest that an introduction of XR-NTX in Europe may increase the number of opioid-dependent individuals in treatment.

Effectiveness, safety and feasibility of extended-release naltrexone for opioid dependence: a 9-month follow-up to a 3-month randomized trial

BACKGROUND AND AIM

This is a follow-up study of a previously published randomized clinical trial conducted in Norway that compared extended-release naltrexone (XR-NTX) to buprenorphine-naloxone (BP-NLX) over 3 months. At the conclusion of the trial, participants were offered their choice of study medication for an additional 9 months. While BP-NLX was available at no cost through opioid maintenance treatment programmes, XR-NTX was available only through study participation, accounting for why almost all participants chose XR-NTX in the follow-up. The aim of this follow-up study was to compare differences in outcome between adults with opioid dependence continuing XR-NTX and those inducted on XR-NTX for a 9-month period, on measures of effectiveness, safety and feasibility.

DESIGN

In this prospective cohort study, participants were either continuing XR-NTX, changed from BP-NLX to XR-NTX or re-included into the study and inducted on XR-NTX treatment.

SETTING

Five urban, out-patient addiction clinics in Norway.

PARTICIPANTS

Opioid-dependent adults continuing (n = 54) or inducted on (n = 63) XR-NTX.

INTERVENTION

XR-NTX administrated as intramuscular injections (380 mg) every fourth week.

MEASUREMENTS

Data on retention, use of heroin and other illicit substances, opioid craving, treatment satisfaction, addiction-related problems and adverse events were reported every fourth week.

FINDINGS

Nine-month follow-up completion rates were 51.9% among participants continuing XR-NTX in the follow-up and 47.6% among those inducted on XR-NTX. Opioid abstinence rates were, respectively, 53.7 and 44.4%. No significant group differences were found in use of heroin and other opioids.

CONCLUSIONS

Opioid-dependent individuals who elect to switch from buprenorphine-naltrexone treatment after 3 months to extended-release naltrexone treatment for 9 months appear to experience similar treatment completion and abstinence rates and similar adverse event profiles to individuals who had been on extended-release naltrexone from the start of treatment.

Design of a randomized controlled trial of extended-release naltrexone versus daily buprenorphine-naloxone for opioid dependence in Norway (NTX-SBX)

BACKGROUND

Current guidelines for opioid dependence recommend daily maintenance of physical dependence with methadone or buprenorphine, and discourage abstinence due to the high risk of relapse and overdose. Extended-release formulations of the opioid antagonist naltrexone (XR-NTX) block heroin and other opioid agonists competitively for around 4 weeks per administration. XR-NTX thus enables opioid users to experience abstinence from opioid agonists with greatly reduced risk of overdose compared to medication-free abstinence. While XR-NTX has shown promise compared to placebo and daily naltrexone tablets, there is limited information on long-term safety and its performance compared to daily maintenance treatment.

METHODS/DESIGN

In this five-hospital RCT with long-term follow-up, we aim to recruit n = 180 patients in treatment for opioid dependence and allocate them in an open, randomized manner (1:1) to receive either 4-week XR-NTX or daily buprenorphine-naloxone (BP-NLX) for the duration of 12 weeks. Allocation is open-label due to the risk of overdose during attempts to self-unmask allocation using heroin. Urine drug tests are scheduled every week with follow-up visits & assessment every 4 weeks. Primary outcomes are abstinence from illicit opioids in urine drug tests and self-report, as well as retention in treatment. Secondary outcomes include other substance use, injecting behavior, drug craving, mental health, quality of life, treatment satisfaction, abstinence motivation, opioid agonist effect rating, insomnia, and pain. Observation is continued for another 36 weeks in order to assess longer-term safety, adherence and effectiveness. The study is an investigator-initiated trial, funded by public grants and approved by an Independent Ethical Committee (the Regional Ethical Committee for Research South-East B # 2011/1320) and the Norwegian Medicines Agency.

DISCUSSION

Despite minor implementation problems, the protocol appears sufficiently robust to generate results of high interest to patients, clinicians and policy makers.

TRIAL REGISTRATION

Clinicaltrials.gov # NCT01717963 , first registered: Oct 28, 2012. Protocol version # 3C, June 12th 2012.

Interest in Extended Release Naltrexone among Opioid Users

BACKGROUND/AIMS

Treatment for addiction to illicit opioids has, thus far, been limited to 2 main approaches: maintaining physical dependence by administering opioids medically and medication-free abstinence with psychosocial support. Assisted abstinence by taking daily tablets with the opioid antagonist naltrexone is rarely practiced, but it is unclear whether this is due to the limited efficacy of this method or because of user opposition to antagonist medication. Therefore, we wanted to investigate opioid users' interest in antagonist treatment with naltrexone, administered as extended release injection, which supports abstinence by blocking illicit opioids for 4-5 weeks per administration.

METHOD

A one-page questionnaire was distributed among opiate users at a broad range of outreach facilities and a total of 731 answered surveys were analysed.

RESULTS

More than half of the opioid users in our study were 'very' or 'quite' interested in receiving a 4-weekly opioid-blocking medication for a year (n = 421), while less than a quarter (n = 164) were 'not interested' at all.

CONCLUSION

We discovered a high user interest for naltrexone treatment, suggesting that the interest for such treatment was not a barrier to the implementation of extended release naltrexone treatment.