Randomized Trial of Long-Acting Sustained-Release Naltrexone Implant vs Oral Naltrexone or Placebo for Preventing Relapse to Opioid Dependence
Arch Gen Psychiatry. 2012;69(9):973-981.
In St. Petersburg, 306 opiate dependent patients randomized to Naltrexone 1000 mg implant or Naltrexone 50 mg tabs daily. This was a double placebo trial so patients either received active implant / placebo pills OR placebo implant / active pills OR placebo implant / placebo pills. The implant they used last two months and a new implant was placed every two months. All patients had biweekly counseling.
The average patient had an 8 year history of opiate dependence. 47% were HIV positive, 95% where Hep C positive.
Of the naltrexone implant group 53% were still in treatment at 6 months vs 16% of the naltrexone tab and 11% of the double placebo patients. Assuming missed urine tests were positve, 63% of the implant patient urines were negative vs 47% for the naltrexone po and 34% of the placebo only patient's urines. At 9 months, after the trial and medication had completed 25 patients came for follow up and 21 were still sober: 12/102 implant patients, 4/102 oral naltrexone and 5/102 placebo
There were 12 wound infections out of 244 implantations. All resolved with antibiotics. Four patients had local allergy like symptoms, treated with an antihistamine. "Non local " side effects were reported by 1% of patients in all treatment groups. There were no significant ALT or AST changes. They noted no increased risk of overdose death due to relapse but don't state how they came to this conclusion.
Naltrexone was started after outpatient detox and a 0.8 mg naloxone IM challenge.
This trial demonstrates what we have assumed, that longer acting naltrexone is more effective than oral naltrexone for the treatment of opiate dependence.
These trials are done in Russia where opiate maintenance therapy is not allowed. It doesn't speak to the choice of naltrexone vs methadone or buprenorphine maintenance. It is noteworthy that these were patients with a serious history of IV opiate dependence, but they still achieved a 53% success rate. Is it certainly likely that more would have remained in treatment on an opiate maintenance medication. It is also noteworthy that almost everyone relapsed when the medication trial was completed as we have seen with other medication treatments for chronic addiction.
