Naltrexone-bupropion more effective than placebo for methamphetamine use disorder

Responses to combination naltrexone-bupropion therapy among adults with methamphetamine use disorder were “low” but higher than responses to placebo, researchers reported.

Currently, there are no FDA-approved treatments for methamphetamine use disorder, according to Madhukar H. Trivedi, MD, a professor in the department of psychiatry at the University of Texas Southwestern Medical Center, and colleagues.

“Long-term methamphetamine misuse has been shown to cause diffuse changes to the brain, which can contribute to severe health consequences beyond addiction itself,” Trivedi said in a press release. “The good news is that some of the structural and neurochemical brain changes are reversed in people who recover, underscoring the importance of identifying new and more effective treatment strategies.”

Trivedi and colleagues assessed the effectiveness of naltrexone-bupropion during a multisite, double-blind, two-stage, placebocontrolled trial. In the first stage of the trial, which was the first 6 weeks, Trivedi and colleagues randomly assigned 403 patients with moderate or severe methamphetamine use disorder to receive 380 mg of extended-release injectable naltrexone every 3 weeks and oral 450 mg of extended-release bupropion daily (n = 109) or a matching placebo (n = 294). In stage 2, also lasting 6 weeks, stage 1 patients who did not respond to placebo were randomly assigned to receive the same naltrexone-bupropion therapy (n = 114) or placebo (n = 111).

Naltrexone’s 3-week administration schedule was chosen to “mitigate the lower naltrexone blood levels that would most likely occur with a 4-week injection schedule,” the researchers wrote in The New England Journal of Medicine. Starting on the day of randomization or rerandomization, the researchers increased the extended-release bupropion dose over 3 days to reach the maximum daily dose of 450 mg.

“If appropriate, doses could be reduced before week 13 to 300 mg per day to alleviate adverse effects; clinicians were encouraged to attempt to raise the dose back up to the target dose,” the researchers wrote.

Injections were administered by trial staff. Patients were asked to use an app to track their adherence to the oral medication and visited their trial site to provide a urine sample twice a week.

According to Trivedi and colleagues, at the end of stage 1, 16.5% of patients in the naltrexone-bupropion group and 3.4% in the placebo group met the primary endpoint: at least three urine samples out of a possible four that tested negative for methamphetamine. At the end of stage 2, these percentages were 11.4% and 1.8%, respectively. The weighted average response across both stages was 13.6% with naltrexone-bupropion and 2.5% with placebo, for an overall treatment effect of 11.1 percentage points (P < .001). The most common adverse events that occurred more frequently across both stages in naltrexone-bupropion recipients vs. placebo recipients were nausea (n = 73), vomiting (n = 25), headache (n = 24), dizziness (n = 18) and fatigue (n = 15). The P value for all adverse events that occurred more frequently among the naltrexone-bupropion group than the control group was less than 0.05.

“There is a growing crisis of overdose deaths involving methamphetamine and other stimulants,” Nora D. Volkow, MD, director of the National Institute of Drug Abuse, said in the release. “This advance demonstrates that medical treatment for methamphetamine use disorder can help improve patient outcomes.”

The researchers recommended that future trials examine how patients with methamphetamine use disorder respond to longer naltrexone-bupropion treatment doses or concurrent behavioral therapy, according to the release.