Mirtazapine for Methamphetamine Use Disorder: A Randomized Clinical Trial

Area of Science:

• Pharmacology
• Psychiatry
• Clinical Trials

Background:

• Methamphetamine use disorder (MUD) is a global health concern lacking approved pharmacotherapies.
• Mirtazapine shows promise for MUD, but its safety and effectiveness in routine practice require evaluation.

Purpose of the Study:

• To assess the safety and effectiveness of mirtazapine as a pharmacotherapy for MUD in a real-world clinical setting.

Main Methods:

• A phase 3, double-blind, placebo-controlled randomized trial involving 339 adults with moderate to severe MUD across 6 Australian outpatient clinics.
• Participants received either mirtazapine (30 mg daily) or placebo for 12 weeks.
• The primary outcome was the change in days of methamphetamine use over 28 days from baseline to week 12.

Main Results:

• Mirtazapine significantly reduced methamphetamine use by a mean of 7.0 days compared to 4.8 days in the placebo group (mean difference: 2.2 days; P=.02).
• Increased drowsiness (47% vs 33%) and weight gain (10% vs 3%) were more common with mirtazapine.
• Adverse events led to discontinuation in 23% of the mirtazapine group versus 15% of the placebo group.

Conclusions:

• Mirtazapine effectively reduced methamphetamine use in adults with MUD within a routine clinical practice setting.
• No unexpected safety concerns were identified, offering a potential treatment option in the absence of approved pharmacotherapies.