Acamprosate — Campral — is the other major medication for alcohol use disorder, alongside naltrexone. The mechanism is different and the clinical positioning is different. Where naltrexone reduces craving and reward in active or early-recovery drinking, acamprosate addresses the protracted post-acute withdrawal state in abstinent patients.
- Class
- Anti-craving agent for AUD
- Mechanism
- Mechanism not fully understood — modulates glutamate (NMDA antagonism) and possibly GABA. May normalize hyperglutamatergic state of post-acute withdrawal.
- Typical dose
- 666 mg TID (two 333 mg tablets)
- Half-life
- ~20-33 hours
- FDA indications
- Maintenance of alcohol abstinence in patients who have completed detoxification
- Key adverse effects
- Diarrhea (most common), headache, nausea, fatigue. Generally well-tolerated. Renal excretion — dose adjust in renal impairment.
For maintenance of abstinence — not for actively drinking patients. Best evidence in patients who have achieved abstinence and want to maintain. TID dosing is adherence barrier. Pure renal excretion makes it usable in hepatic impairment (vs. naltrexone hepatotoxicity).
The mechanism is glutamate modulation. Chronic alcohol use upregulates NMDA glutamate signaling; sudden cessation leaves the brain in a hyperglutamatergic state that contributes to prolonged craving, anxiety, and dysphoria during early recovery. Acamprosate has NMDA antagonist properties and modulates GABA — together attenuating the hyperglutamatergic state. The clinical effect is reduced relapse rate and improved abstinence maintenance.
Acamprosate supports alcohol abstinence through a glutamatergic mechanism — restoring the excitatory-inhibitory balance disrupted by chronic alcohol use.
Mechanism note: Acamprosate restores glutamatergic balance to support alcohol abstinence; it is renally cleared (safe in liver disease) but its TID dosing and GI effects are practical adherence hurdles.
Crucially, acamprosate is for maintenance of abstinence after detoxification, not for active drinking. The patient must have stopped drinking before starting; the drug helps sustain that. This differentiates from naltrexone, which can be started while the patient is still drinking.
The pharmacology has some practical advantages. Acamprosate is excreted renally — no hepatic metabolism — making it usable in hepatic impairment where naltrexone hepatotoxicity is a concern. For the patient with AUD and cirrhosis, acamprosate is often the better choice. Dose-adjust in significant renal impairment.
The major practical drawback is the dosing schedule: TID. Three times daily is a meaningful adherence challenge for any chronic medication, and substance use disorder patients often have additional adherence barriers. The thrice-daily requirement is the most common reason acamprosate trials fail.
- Cost
- Generic: ~$80-200/month.
- Generic status
- Generic for years.
- Formulary typical
- Tier 2-3. Sometimes PA.
- Access friction
- TID dosing is the adherence pain. Patient support programs limited.
Prescriber tip: For abstinent AUD patient with hepatic disease, often the preferred agent over naltrexone. Address the TID dosing barrier explicitly at prescription — patients often don't take all three doses.
Side effects are generally mild and well-tolerated. Diarrhea is the most common. Headache, nausea, fatigue, occasional dizziness. Generally tolerable in the context of recovery.
For abstinence maintenance — particularly in patients with hepatic concerns where naltrexone is problematic — acamprosate is an established choice. Combined with behavioral support, mutual-help groups, and ongoing engagement, it improves outcomes.