15 November 2017. A clinical trial testing two leading therapies for opioid abuse found the treatments both safe and effective, even though they work in different ways. Results of the comparative effectiveness study, led by researchers at New York University medical school appear in yesterday’s issue of the journal The Lancet (paid subscription required).
The team led by psychiatry professor John Rotrosen and population health specialist Joshua Lee, the paper’s senior and first authors respectively, sought evidence to support choosing between two of the leading drugs prescribed in opioid treatment programs, extended-release naltrexone or a combination of buprenorphine and naloxone. Extended-release naltrexone, marketed as Vivitrol by Alkermes Inc. is given as a monthly injection, while the buprenorphine-naloxone combination, marketed as Suboxone by Indivior Inc. is taken by patients daily as a film dissolved under the tongue.
The drugs work in quite different ways. Vivitrol, the extended-release naltrexone, blocks the activation of opioid receptors and requires complete detoxification before beginning treatment. Suboxone, the combination of buprenorphine and naloxone, still activates opioid receptors, but only mildly, which helps reduce cravings and withdrawal symptoms. The need for complete removal of opioids from the body limits the use of Vivitrol for many prospective patients, while Suboxone can be used as a maintenance drug in a structured treatment program. The two drugs had not been previously evaluated head-to-head.
The clinical trial, funded in part by National Institute on Drug Abuse at National Institutes of Health, enrolled 570 adults addicted to heroin or prescription opioid drugs, and still taking non-prescribed opioids. Participants were recruited from 8 residential treatment facilities in the U.S., where they were randomly assigned to receive either Vivitrol or Suboxone as part of their therapies. The treatments continued for 24 weeks, including outpatient follow-ups after the residential programs.
Rotrosen, Lee, and colleagues looked primarily at relapse-free survival during the 24 weeks, with relapse defined as any non-prescribed opioid use, detected in urine tests and reports from participants themselves. The results show, as expected, a larger percentage of recruits for the study receiving Suboxone (94%) were able to participate in the full treatment programs than those receiving Vivitrol (72%), who first needed to completely detox. As a result, somewhat more of the total participants successfully began their treatment programs with Suboxone (65%) than Vivitrol (57%).
Among participants successfully starting their programs, however, the early relapse percentages are about the same for the two treatments — 52 percent for Vivitrol and 56 percent for Suboxone — both in their urine samples and number of days remaining clean. Self-reported opioid craving was at first lower among Vivitrol recipients, but by the end of the study became similar for both treatment groups. Some Vivitrol recipients experienced mild to moderate injection site reactions, but the number of treatment-related adverse events were otherwise about the same for both groups. Those adverse events include overdoses, including 5 fatal overdoses during the study.
The researchers conclude the two drugs provide different strategies for treating opioid abuse, but once initiated are both safe and equally effective. “The good news is we filled the evidentiary void,” says Rotrosen in a NIDA statement, “and also learned that for those who were able to initiate treatment, the outcomes were essentially identical, as were adverse events. This gives patients the freedom to choose a treatment approach that best suits their lifestyle, goals and wishes.”
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