Acamprosate: Effectiveness in Alcohol Withdrawal

Acamprosate (brand name Campral and generics) is an active substance for relapse prevention after successful alcohol withdrawal. It has been available in France since 1989 and in Germany since the 1990s. Acamprosate reduces alcohol cravings and supports the maintenance of abstinence, ideally embedded in a psychotherapeutic and social-medical framework. Studies show a moderate but consistent reduction in relapse rates, especially in patients who have already completed detoxification.

Compared to naltrexone and disulfiram, the other active substances available in Germany for alcohol relapse prevention, acamprosate has its own profile. It does not act as a deterrent like disulfiram and does not block the rewarding effects of alcohol like naltrexone. Instead, it normalizes glutamate and GABA imbalances that persist after chronic alcohol use and sustain addiction memory. This effect is subtle but clinically significant in many patients.

Mechanism of Action

Acamprosate is a synthetic calcium salt of homotaurine acetic acid. Structurally, it resembles the amino acids glutamate and GABA, which explains its primary mechanism of action. Chronic alcohol consumption leads to persistently elevated glutamate activity and reduced GABA function in the central nervous system. After withdrawal, this imbalance persists and drives craving and relapse risk, often for months. Acamprosate modulates NMDA receptor activity and stabilizes the glutamate system, which reduces the urge to drink.

In animal models, acamprosate shows a reduction in alcohol-associated learning stimuli and stabilization of stress-induced cravings. In clinical settings, this means reduced reactivity to alcohol cues such as advertising, smell, or social drinking situations. However, the effect is not acutely noticeable; it develops over weeks and is statistically demonstrable, not always subjectively obvious.

Oral bioavailability is only 11 percent, but is reproducible on an empty stomach. Acamprosate is not hepatically metabolized but is excreted unchanged renally. The half-life is 20 to 33 hours. Drug interactions with hepatically metabolized medications are therefore minimal, which is an advantage in patients with alcohol-related liver involvement.

Indications

• Relapse prevention after alcohol withdrawal in patients with alcohol dependence who are motivated to abstain and have completed detoxification
• Support for psychotherapeutic and psychosocial interventions in addiction medicine
• Off-label use in reducing subjective craving in specialized settings

Acamprosate does not replace detoxification. It is usually started after completion of the physical withdrawal phase and ideally used as part of multimodal addiction therapy. During active alcohol use or acute withdrawal, it is not the agent of choice because symptomatic withdrawal medication and safety take priority.

Dosage and Administration

Adults weighing more than 60 kg: 666 mg three times daily (1998 mg per day), standard dose for most patients.

Adults weighing less than 60 kg: 666 mg in the morning, 333 mg at midday, and 333 mg in the evening, i.e., 1332 mg per day.

Duration of therapy: at least six months, often twelve months. Shorter therapy significantly reduces the effect. If therapy is successful, the duration can be extended individually.

Administration: Take tablets whole with plenty of water, preferably at fixed times. Taking on an empty stomach improves bioavailability but is not mandatory.

Renal impairment: contraindicated if eGFR is below 30 ml per minute due to risk of accumulation. With eGFR 30 to 60, individual adjustment with lower dose and close monitoring.

Hepatic impairment: generally no dose adjustment because no hepatic metabolism. Use caution in very advanced liver disease due to possible concomitant complications.

In case of relapse: do not stop therapy abruptly; return to abstinence with medical supervision. The effect of acamprosate builds up again if therapy is continued after a brief pause.

Side Effects

Very common: Diarrhea, abdominal pain, nausea, bloating.

Common: Headaches, sleep disorders, loss of libido, pruritus, rash.

Occasional to rare: Confusion, mood swings, depressive episodes, edema, hypertension, allergic skin reactions.

Important to note: Diarrhea is the most common side effect, especially in the first weeks. It is usually mild and dose-dependent. Gradual dose titration or taking with meals can help. For more severe diarrhea, consult a physician.

Suicide risk: patients with alcohol dependence have an increased baseline risk. Acamprosate does not directly alter this risk, but psychiatric consultation should occur if depressive symptoms or suicidal thoughts develop.

Drug Interactions

• Alcohol: when consumed during therapy, acamprosate is not antagonized, but the harmful effects of alcohol consumption remain unchanged. Continued reduction in drinking is the treatment goal.
• Naltrexone: combination therapy examined in some studies, effect-enhancing, side effect profile to be considered.
• Disulfiram: combination possible, additive effects on drinking behavior, individual indication.
• Diuretics: with combined use, electrolyte monitoring as diarrhea under acamprosate can cause additional losses.
• Antidepressants (SSRI, SNRI, tricyclics): common concomitant medication in patients with depressive comorbidity, no direct pharmacokinetic interactions.
• Other central nervous system active medications: no specific interaction, but careful psychiatric monitoring is advisable.

Special Notes

Pregnancy: Data limited, use during pregnancy is not recommended. Women of childbearing age should use reliable contraception or decide after individual counseling. Breastfeeding: Transfer into breast milk, nursing during therapy not recommended.

Children and adolescents: not approved.

Elderly patients: Caution due to renal impairment, lower doses and close follow-up..

Before starting therapy: Complete history with substance use history, psychiatric comorbidities, living circumstances, treatment motivation. Laboratory work with liver and kidney values, pregnancy test. Counseling about treatment goals, possible side effects, duration of therapy, and importance of psychotherapeutic support.

Multimodal approach: Acamprosate alone has moderate effectiveness. Combined with addiction therapy, self-help groups, cognitive behavioral therapy, social stabilization, and treatment of psychiatric comorbidities as needed, effectiveness is significantly higher.

Behavior in case of relapse: a relapse is not a treatment failure but part of the addiction process. Therapy should be continued, supplemented by reflection on triggering factors and adjustment of supporting measures.

Lifestyle: Structured daily routine, physical activity, nutrition, social contacts without alcohol context, avoidance of typical drinking situations, stress management, and sleep hygiene sustainably support abstinence.

Driving ability: generally retained, individual assessment if pronounced drowsiness or dizziness occurs.

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• Buprenorphine, substitution agent for opioid dependence
• Methadone, substitution agent for opioid dependence

Frequently Asked Questions

Sources

• Gelbe Liste, Acamprosate active substance profile
• BfArM, Federal Institute for Drugs and Medical Devices
• AWMF, S3 Guideline Alcohol-Related Disorders
• German Central Agency for Addiction Issues