What is the recommended dosing for Acamprosate (Campral) in patients with Impaired renal function?

Acamprosate Dosing in Renal Impairment

For patients with impaired renal function, acamprosate dosing should be reduced to 333 mg three times daily in moderate renal impairment (creatinine clearance 30-50 mL/min) and is contraindicated in severe renal impairment (creatinine clearance ≤30 mL/min). 1

Dosing Recommendations Based on Renal Function

The FDA-approved dosing guidelines for acamprosate (Campral) in patients with varying degrees of renal function are as follows:

• Normal renal function: 666 mg (two 333 mg tablets) three times daily
• Moderate renal impairment (CrCl 30-50 mL/min): 333 mg (one tablet) three times daily
• Severe renal impairment (CrCl ≤30 mL/min): Contraindicated - do not use

Pharmacokinetic Rationale

Acamprosate's pharmacokinetic properties explain why dose adjustment is necessary in renal impairment:

• Acamprosate is not metabolized by the liver and is primarily eliminated unchanged in the urine 2
• Approximately 50% of the drug is excreted unchanged in urine, with the remainder likely eliminated via biliary excretion 2
• The drug has a moderate distribution volume of about 20L and is not protein-bound 2
• Patients with renal impairment will have decreased clearance of acamprosate, leading to drug accumulation and potential toxicity

Clinical Considerations

When prescribing acamprosate to patients with alcohol use disorder who have renal impairment:

• Always assess renal function before initiating therapy
• Monitor renal function periodically during treatment, especially in patients with borderline renal function
• Consider alternative medications for alcohol abstinence maintenance in patients with severe renal impairment:
  • Baclofen may be considered as an alternative, as it has shown efficacy in maintaining abstinence in patients with liver cirrhosis 3
  • However, monitor closely for sedation and mental status changes with baclofen, especially in patients with hepatic encephalopathy 3

Treatment Duration and Monitoring

• Acamprosate treatment should be initiated as soon as possible after alcohol withdrawal when the patient has achieved abstinence 1
• The typical treatment duration is 3-6 months 3
• The medication should be used as part of a comprehensive psychosocial treatment program 1
• No dosage adjustment is required for hepatic impairment 4

Important Precautions

• Acamprosate contains sodium sulfite, which may cause allergic reactions in susceptible individuals 1
• Monitor for suicidal ideation, as suicidal events were more common in acamprosate-treated patients than placebo in clinical trials 1
• Acamprosate absorption is decreased when taken with food, though dosing with meals was employed during clinical trials 1

By following these evidence-based dosing recommendations for acamprosate in patients with renal impairment, clinicians can help maximize the medication's efficacy while minimizing the risk of adverse effects in this vulnerable population.