Seeking assistance to achieve sobriety, a 48-year-old male construction worker presents to… — USMLE Step 2 CK

Seeking assistance to achieve sobriety, a 48-year-old male construction worker presents to an addiction medicine clinic. He reports consuming a half-liter of vodka daily and feels unable to quit relying on willpower alone. His medical history is notable for a previous heroin addiction, which has been in stable remission for three years via daily buprenorphine-naloxone therapy. He was also diagnosed with chronic hepatitis C two years ago but has not received antiviral treatment. Vital signs are within normal limits. Physical examination shows a calm, cooperative patient with no tremors, diaphoresis, or autonomic instability.

Laboratory evaluation reveals:

Test	Result	Reference Range
Aspartate aminotransferase (AST)	120 U/L	8-40 U/L
Alanine aminotransferase (ALT)	95 U/L	7-56 U/L
Total bilirubin	1.1 mg/dL	0.1-1.2 mg/dL
Serum creatinine	0.8 mg/dL	0.7-1.3 mg/dL

The patient requests a medication to help reduce his alcohol consumption. Which of the following is the most appropriate pharmacotherapy for this patient?

AcamprosateAnswer
B
Naltrexone
C
Disulfiram
D
Chlordiazepoxide
E
Sertraline

Answer

Acamprosate

The most appropriate medication for this patient is acamprosate. This patient is seeking maintenance pharmacotherapy for alcohol use disorder to prevent relapse. The two primary first-line options are naltrexone and acamprosate. However, naltrexone is a mu-opioid receptor antagonist and is absolutely contraindicated in patients actively taking opioids, including partial agonists like buprenorphine, because it will immediately precipitate acute opioid withdrawal. Furthermore, naltrexone and disulfiram both carry risks of hepatotoxicity and should be avoided in patients with active liver inflammation (indicated by this patient's elevated AST and ALT secondary to hepatitis C). Acamprosate is primarily excreted unchanged by the kidneys and does not interact with the hepatic cytochrome P450 system or opioid receptors. Given this patient's normal serum creatinine (

0.8\text{ mg/dL}

), acamprosate is safe and represents the optimal choice.

Step-by-Step Solution

Identify the patient's primary clinical need and timeline.

The patient is seeking long-term maintenance pharmacotherapy to reduce alcohol cravings, not acute withdrawal management.

Establishing the clinical goal rules out acute detoxification agents like benzodiazepines.

Review the patient's medication history for potential drug interactions.

The patient is currently on buprenorphine-naloxone for opioid use disorder.

First-line agents for alcohol use disorder include naltrexone and acamprosate. Naltrexone is an opioid antagonist and will precipitate severe withdrawal in patients on opioid therapies.

Evaluate laboratory results to identify metabolic contraindications.

The patient has active hepatitis C with elevated AST and ALT, but normal serum creatinine.

Liver dysfunction contraindicates hepatotoxic medications like disulfiram and often naltrexone. Acamprosate is renally excreted and is the safest choice for this patient.

Key Concept

Acamprosate is the first-line pharmacotherapy for alcohol use disorder in patients who have concurrent opioid use disorder (where naltrexone is contraindicated) or significant liver disease, provided their renal function is intact.

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