Naltrexone Does Not Work for Amphetamine Abuse
No pharmacologic treatment for stimulant (amphetamine/methamphetamine) dependence can be recommended for use in primary care, and behavioral therapies remain the only evidence-based treatment approach 1.
The Evidence Against Naltrexone Monotherapy
The FDA drug label explicitly states that naltrexone "has not been shown to affect the use of cocaine or other non-opioid drugs of abuse" 2. This is critical—naltrexone is FDA-approved only for opioid and alcohol use disorders, not stimulants.
Guideline Consensus
Multiple guidelines from 2013 consistently state: "Despite continued research efforts and several potential candidate medications, no pharmacologic treatment for stimulant (e.g., cocaine, methamphetamine) dependence can be recommended for use in the primary care setting" 1. These guidelines emphasize that behavioral therapies have demonstrated effectiveness where medications have failed 1.
Research Evidence Shows Minimal to No Benefit
The most recent and comprehensive evidence contradicts any benefit:
2025 systematic review and meta-analysis found no significant difference between naltrexone and placebo for amphetamine use (RR=0.903), study retention, craving, or serious adverse events. The quality of evidence was low to very low 3.
2018 randomized controlled trial in 100 methamphetamine-dependent men who have sex with men showed naltrexone did not reduce methamphetamine use versus placebo (IRR=0.95), despite 96.7% medication adherence 4.
2023 preclinical study demonstrated naltrexone failed to reduce amphetamine choice in both rhesus monkeys and rats, arguing against its use as either maintenance medication or abuse-deterrent 5.
The Naltrexone-Bupropion Combination: A Different Story
While naltrexone alone doesn't work, the combination of extended-release naltrexone plus bupropion shows modest but statistically significant benefit:
2021 ADAPT-2 trial (the highest quality evidence available) showed 13.6% response rate with naltrexone-bupropion versus 2.5% with placebo—an 11.1 percentage point difference (P<0.001) 6. However, this represents a very low absolute response rate.
The effect is modest: only 16.5% responded in stage 1 and 11.4% in stage 2 6.
Important Caveats About Combination Therapy
The combination works through synergistic effects on hypothalamic appetite centers and mesolimbic reward circuits 7, not through opioid antagonism alone. This is fundamentally different from naltrexone monotherapy.
Common pitfall: Prescribing naltrexone alone based on the combination therapy data. The evidence does not support this extrapolation 3.
What Actually Works: Behavioral Interventions
Contingency management (CM) demonstrates the most robust efficacy, increasing abstinence rates by 40-60% 8. This is far superior to any pharmacological approach.
Other effective behavioral approaches include:
- Cognitive behavioral therapy combined with any pharmacotherapy shows benefit over usual care 9
- Motivational enhancement therapy
- Matrix model intensive outpatient programs
Clinical Algorithm for Amphetamine Use Disorder
First-line treatment: Refer to behavioral therapy, specifically contingency management programs 1, 8
Consider combination naltrexone-bupropion only if:
- Patient has failed behavioral interventions alone
- No contraindications exist (seizure history, uncontrolled hypertension, concurrent opioid use)
- Patient understands the modest benefit (only ~11% absolute improvement)
- Close monitoring for neuropsychiatric effects is feasible 6
Do NOT prescribe naltrexone monotherapy for amphetamine use disorder—the evidence does not support this practice 3, 4
Refer to addiction specialist if:
- Comorbid psychiatric disorders are uncontrolled
- Co-occurring alcohol or benzodiazepine abuse exists
- Office-based treatment has been ineffective 1
Critical Safety Considerations
- Naltrexone blocks opioid effects completely—cannot be used in patients requiring pain management with opioids 1, 10
- Monitor liver function at baseline and every 3-6 months 1
- Screen for pregnancy (teratogenic with bupropion component) 7
- Assess seizure risk before initiating combination therapy 10
- The OPRM1 A118G polymorphism predicts poor response, though genetic testing is not yet standard of care 11
Bottom line: Naltrexone alone does not work for amphetamine abuse. The combination with bupropion shows statistically significant but clinically modest benefit. Behavioral therapies, particularly contingency management, remain the most effective intervention and should be the foundation of treatment.