Acamprosate calcium

Campral® (acamprosate calcium) — explanation for a clinical pharmacist

Overview & Indication

  • Campral (acamprosate calcium) is indicated for the maintenance of abstinence in alcohol use disorder (AUD).
  • It is most effective when initiated after detoxification and used in conjunction with psychosocial support.

Mechanism of Action

  • Acamprosate modulates glutamatergic and GABAergic neurotransmission.
  • Chronic alcohol use upregulates NMDA/glutamate activity; during abstinence this contributes to hyperexcitability and craving.
  • Acamprosate is thought to attenuate glutamate hyperactivity (functional NMDA antagonism) and enhance inhibitory balance, thereby reducing protracted withdrawal symptoms and craving.
  • It does not produce aversion to alcohol and does not reduce acute intoxication effects.

Pharmacokinetics

  • Absorption: Oral; bioavailability ~11%; food decreases absorption but not clinically significant.
  • Distribution: Minimal protein binding.
  • Metabolism: Not hepatically metabolized (advantage in liver disease).
  • Elimination: Renal excretion unchanged.
  • Half-life: ~20–33 hours.

Dosing

  • Standard dose: 666 mg PO three times daily.
  • Renal adjustment:
    • CrCl 30–50 mL/min: 333 mg PO TID.
    • CrCl <30 mL/min: Contraindicated.
  • Can be started once abstinence is achieved; continue even if lapse occurs (unless full relapse).

Efficacy

  • Best at maintaining abstinence, not initiating it.
  • More effective in patients who are already abstinent and motivated.
  • Modest effect size; works best as part of multimodal treatment.

Adverse Effects

  • Most common: diarrhea (dose-related), nausea, flatulence.
  • Others: pruritus, rash, dizziness, anxiety, insomnia.
  • Rare: suicidal ideation (monitor mood, especially in AUD patients).

Contraindications & Precautions

  • Severe renal impairment (CrCl <30 mL/min).
  • Caution in moderate renal impairment.
  • Pregnancy: limited data; use only if benefit outweighs risk.

Drug Interactions

  • Minimal clinically significant drug–drug interactions.
  • Safe to use with antidepressants, benzodiazepines (short term), and naltrexone.

Clinical Pearls

  • Advantage over naltrexone in patients with hepatic impairment.
  • Requires TID dosing, which may affect adherence.
  • No abuse potential; not a controlled substance.
  • Educate patients that it reduces craving/withdrawal distress, not the pleasurable effects of alcohol.
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