Randomized trialOpioid use disorder2011
Krupitsky 2011: the Vivitrol shot for opioid dependence after detox
Krupitsky E, Nunes EV, Ling W, Illeperuma A, Gastfriend DR, Silverman BL. Injectable extended-release naltrexone for opioid dependence: a double-blind, placebo-controlled, multicentre randomised trial
What it found
People given the monthly naltrexone shot (Vivitrol, 380 mg) had confirmed abstinence from opioids in a median 90.0% of weeks, against 35.0% for those on placebo injections. They also had less craving and stayed in treatment longer, in a trial funded by Alkermes.
- Weeks with confirmed abstinence, Vivitrol (median)
- 90.0%
- Weeks with confirmed abstinence, placebo (median)
- 35.0%
- Median days in treatment, placebo (Vivitrol: over 168)
- 96 days
- Relapsed to physical opioid dependence, Vivitrol vs placebo
- 1 vs 17
What they tested
250 adults at 13 clinics in Russia were randomly assigned to monthly injections of extended-release naltrexone 380 mg (126 people) or placebo injections (124 people) for 24 weeks. All had finished inpatient detox and been off opioids for at least 7 days. Patients, researchers, staff and the sponsor didn't know who got which.
Everyone also had 12 counseling sessions, one every two weeks. The main measure was confirmed abstinence in weeks 5 to 24, checked with urine drug tests and people's own reports.
What they found
The median share of weeks with confirmed abstinence was 90.0% on the shot and 35.0% on placebo. People on the shot reported a median 99.2% of days opioid-free, against 60.4% on placebo.
Craving scores fell by an average of 10.1 on the shot and barely changed on placebo (0.7).
Median time in treatment was over 168 days on the shot, against 96 days on placebo. Testing confirmed that 17 people on placebo had become physically dependent on opioids again, against one on the shot.
The shot was well tolerated. Two people in each group stopped because of side effects, and no one on the shot died, overdosed or stopped because of a severe side effect.
Limits
- Alkermes, the company behind Vivitrol, paid for the trial.
- All 13 sites were in Russia, and everyone had already finished detox and been opioid-free for at least a week, so it doesn't cover people who can't get through that first step.
- It compared the shot with placebo for 24 weeks, not with buprenorphine or methadone, and it doesn't show what happened after the shots stopped.
What it means if you're considering naltrexone
For someone who has already detoxed from opioids and wants a medicine that isn't itself an opioid, this trial shows the monthly shot helped people stay off opioids over 24 weeks, compared with placebo. The site's Vivitrol guide notes that this is the trial behind the opioid figures on the current Vivitrol label, and that the FDA added the opioid use in October 2010.
It doesn't tell you how the shot compares with buprenorphine or methadone. The site's guides cover those comparisons using other trials.
Frequently asked questions
Does Vivitrol work for opioid addiction?
In this 24-week trial of 250 adults who had finished detox, people on the shot had confirmed abstinence in a median 90.0% of weeks, against 35.0% on placebo.
Who funded the Krupitsky 2011 Vivitrol trial?
Alkermes funded it. The sponsor, like the patients and staff, was kept unaware of who got the real drug.
The paper
Krupitsky E, Nunes EV, Ling W, Illeperuma A, Gastfriend DR, Silverman BL. Injectable extended-release naltrexone for opioid dependence: a double-blind, placebo-controlled, multicentre randomised trial. Lancet. 2011;377(9776):1506-1513. doi:10.1016/S0140-6736(11)60358-9
Read the paperdoi:10.1016/S0140-6736(11)60358-9
We wrote this page from the paper's published abstract, and the study's numbers here come from there. Updated October 17, 2026.
Medical disclaimer
This page is for information only and is not medical advice, diagnosis, or treatment. Don't start, stop, or change any medicine — including naltrexone — without your prescriber. Naltrexone must not be used by people taking opioid pain medicines, people dependent on opioids, or people in opioid withdrawal (FDA label). In an emergency call 911; for crisis support call or text 988. Full medical disclaimer.