Meta-Analysis of Naltrexone & Acamprosate for Treating Alcohol Use Disorders
When are these medications most helpful?
Naltrexone and acamprosate are medications approved to treat alcohol use disorders.
Maisel and colleagues performed a review and meta-analysis to indentify when naxltrexone and acamprosate are most helpful by measuring the relative efficacy of each medication for what it is thought to do and whether different ways of implementing each medication (e.g. requiring abstinence before treatment) impacted its effect.
Naltrexone is thought to reduce cravings and help prevent relapse to heavy drinking by reducing the rewarding effects of alcohol if drinking does occur.
Acamprosate is thought to promote abstinence by resetting the balance in the brain that is disrupted in alcohol use disorders. Acamprosate is also thought to be ineffective if the patient begins using alcohol.
The authors thought that whether abstinence was required before treatment, length of abstinence, and whether the goal of treatment was abstinence could have an impact on the effects of the medication.
This study included randomized, placebo-controlled trials that tested the efficacy of naltrexone or acamprosate in adults over the age of 18, that were published between 1970-2009, and included at least one drinking outcome. The authors looked at abstinence, heavy drinking, craving, and heavy drinking and craving together as outcomes. There were 45 trials looking at naltrexone versus placebo (n= 5,434), 16 trials examining acamprosate versus placebo (n=4,349), and 3 studies comparing both medication (n=1,210).
- 54 studies looked at an abstinence outcome
- 47 studies included at least one heavy drinking outcome
- 36 studies included a craving outcome
- Required abstinence before the trial was associated with greater abstinence and greater reductions in heavy drinking for naltrexone
- Naltrexone had larger effect sizes than acamprosate when looking at heavy drinking outcomes (however, this may be due to the lack of data provided for acamprosate about heavy drinking outcomes)
- When heavy drinking and craving outcomes were combined, naltrexone was more effective than acamprosate
- Acamprosate was more effective when abstinence was required before treatment began
The majority of studies included in this research involved a behavioral intervention given to both groups; therefore, many of the studies were not simply comparing medication versus no medication.
The number needed to treat to achieve an additional case of abstinence for acamprosate is 8 and for naltrexone is 9. This suggests that both acamprosate and naltrexone have clinical relevance.
Overall, these results suggest that naltrexone may be more effective for patients who have a goal of reducing heavy drinking days, whereas, acamprosate may be better for patients who seek abstinence.
Alcohol use disorder (AUD) is a high volume, high burden, illness that is often chronic. While it is the third leading cause of preventable death in the United States, it is treatable and most people recover from AUD with time. Treatment can play a big role in aiding recovery efforts, yet because AUD is heavily stigmatized, many people avoid specialty treatment. Medications for AUD are important as they can help improve outcomes and have shown to be effective when delivered by more ubiquitous addiction non-specialists, like primary care physicians. Because seeing one’s primary care physician is not stigmatized it provides an opportunity for many more people with AUD to be treated.
The beneficial effects from naltrexone and acamprosate may differ to some degree in keeping with their purported relative targets: naltrexone to reduce heavy drinking and acamprosate to increase abstinence. More widespread use of medications for AUD in primary care and specialty care offers hope that more people can find a treatment that will help them on their road to remission and recovery.
Maisel, N. C., Blodgett, J. C., Wilbourne, P. L., Humphreys, K., & Finney, J. W. (2013). Meta‐analysis of naltrexone and acamprosate for treating alcohol use disorders: when are these medications most helpful?. Addiction, 108(2), 275-293.