Combination Therapy of Acamprosate and Naltrexone for Alcohol Abstinence
The COMBINE study definitively showed that combining acamprosate with naltrexone does NOT improve abstinence rates compared to naltrexone alone, and acamprosate showed no evidence of efficacy in this large, well-designed trial. 1
Evidence from the COMBINE Study
The landmark COMBINE trial (N=1383) demonstrated that:
- Acamprosate showed no significant effect on drinking versus placebo, either by itself or in any combination with naltrexone or behavioral interventions 1
- Naltrexone with medical management was effective, achieving 80.6% days abstinent 1
- The combination of naltrexone plus acamprosate did not produce better efficacy than naltrexone alone 1
- No combination therapy produced superior outcomes compared to naltrexone or behavioral intervention alone when delivered with medical management 1
Contradictory Evidence from Smaller Studies
While the COMBINE study is definitive, earlier smaller trials suggested potential benefit:
- A 2003 German study (N=160) found combination therapy had significantly lower relapse rates than placebo and acamprosate alone, though not significantly better than naltrexone alone 2
- However, this study's smaller sample size and different clinical context (12 weeks vs. 16 weeks, European vs. US population) limit its applicability 2
Network Meta-Analysis Findings
A 2020 BMJ network meta-analysis provides nuanced context:
- The combination of acamprosate and naltrexone showed improved abstinence versus placebo (OR 3.68,95% CI 1.50-9.02) 3
- However, confidence in this evidence was rated as only moderate quality due to low numbers of studies and patients 3
- When comparing individual agents, acamprosate alone had moderate-quality evidence for maintaining abstinence, while naltrexone's evidence was weaker 3
Clinical Algorithm for Medication Selection
Choose monotherapy based on patient characteristics:
- For maintaining abstinence in detoxified patients: Use acamprosate 1998 mg/day (if ≥60 kg) as first-line, particularly in primary care settings 3
- For patients with liver disease: Use acamprosate exclusively, as naltrexone is contraindicated in hepatic insufficiency 4
- For reducing heavy drinking and craving: Consider naltrexone 100 mg/day over acamprosate 5
- Do NOT routinely combine medications: The COMBINE study provides the highest-quality evidence that combination therapy offers no additional benefit 1
Critical Pitfalls to Avoid
- Do not assume combination therapy is superior based on theoretical mechanisms—the largest randomized trial contradicts this assumption 1
- Do not use naltrexone in patients with alcoholic liver disease due to hepatotoxicity risk and formal contraindication 4, 6
- Ensure patients are detoxified before starting acamprosate (3-7 days post-last drink), as it maintains rather than induces abstinence 4, 7
- Always combine pharmacotherapy with medical management or psychosocial support—medications alone are insufficient 1