A prescription medication used to treat attention deficit hyperactivity disorder (ADHD) could be repurposed as the first pharmacotherapy for people with methamphetamine dependence, according to a study published in Addiction.
Results from the landmark ‘LiMA’ trial show that the psychostimulant lisdexamfetamine can drastically reduce the need to use methamphetamine among those who are dependent on the illicit drug.
Lead author and addiction medicine specialist Professor Nadine Ezard, who is Director of the National Centre for Clinical Research on Emerging Drugs (NCCRED), said the results were promising.
"There is currently no pharmacotherapy approved for treating methamphetamine dependence," Professor Ezard said.
“While further research is needed, experienced clinicians could consider off-label prescription of lisdexamfetamine, with close monitoring of risks and benefits in line with current guidelines for psychostimulants, for people with methamphetamine use disorder.”
As part of the trial, Professor Ezard’s team at NCCRED—which is based at the National Drug and Alcohol Research Centre (NDARC), UNSW Sydney—recruited 164 adults dependent on methamphetamine and who had reported using the drug on at least 14 of the previous 28 days.
Participants were randomly assigned to a 15-week regimen with lisdexamfetamine (one-week induction, 12-week maintenance on 250mg/day, and two-week reduction) or placebo, and tracked for four weeks after treatment.
Overall, those who received lisdexamfetamine had 8.8 fewer days of methamphetamine use on average during the 12-week maintenance phase than those in the placebo group.
Those given the ADHD medication also had higher self-reported rates of treatment effectiveness (2.9 times higher) and treatment satisfaction (3.8 times higher) compared to participants given placebo.
The effects were seen most strongly in the early weeks of the trial.
“While the beneficial effect waned towards the end of the treatment period, exploring the characteristics of ‘early responders’ in our study will be useful to understand who may benefit most from agonist therapies,” Professor Ezard said.
She added that there were no unexpected safety concerns with high-dose lisdexamfetamine, with most adverse events deemed mild or moderate in severity.
Trial participants were recruited from six specialist outpatient clinics in Sydney, Newcastle, Melbourne and Adelaide between May 2018 and December 2021, with a nine-month recruitment suspension in 2020 due to the COVID-19 pandemic.
An important limitation of the study was the high attrition rate of 39%; while this was consistent with other outpatient studies for methamphetamine use disorder, it impacted the statistical strength of the findings.
-ENDS-
Contact details:
Professor Nadine Ezard: 0417 651 267 | nadine.ezard@svha.org.au
NDARC media: 0401 713 850 | ndarc.media@unsw.edu.au
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