Assess Phenobarbital Use for Alcohol Withdrawal

Ongoing benzodiazepine shortages are leading to questions about managing acute alcohol withdrawal syndrome.

Any benzo can be used, depending on your supply.

Try to use oral benzos. Save IV for severe withdrawal.

Calculate dosing equivalents. For example, convert IV or oral lorazepam 1.5 mg to IV or oral diazepam 10 mg...oral chlordiazepoxide 25 mg...or IV midazolam 3 mg.

Keep in mind, lorazepam lacks an active metabolite...diazepam has a longer half-life and can accumulate...and midazolam requires frequent dosing due to its short duration.

Consider propofol a benzo alternative for intubated patients.

Or think of phenobarbital for most patients. But avoid it with significant interactions, such as dolutegravir or ticagrelor.

Phenobarbital seems as effective as benzos to manage symptoms and prevent seizures...and is given orally, IV, or IM. Plus it has predictable kinetics...and a long half-life to allow self-tapering.

Be aware, phenobarbital data are limited...and protocols vary.

Consider a loading dose of 10 mg/kg using ideal body weight. This may reduce ICU admissions. For patients with mild withdrawal, it may prevent the need for additional doses after ED discharge.

But think about skipping a loading dose in some cases...such as severe liver disease or concomitant sedating meds (opioids, etc).

Use a tool to assess symptoms. For example, maintain a score of 8 or less on the Clinical Institute Withdrawal Assessment (CIWA-Ar)...or 0 to -1 on the Richmond Agitation-Sedation Scale (RASS).

If additional doses are needed or if not loading, give prn phenobarbital for symptoms...such as 130 mg IV every 30 minutes.

Monitor for oversedation and respiratory depression...risk seems similar to benzos.

Consider other causes if you exceed a cumulative phenobarbital dose of 20 mg/kg in about 48 hrs...since this dose is often enough. Limit to 30 mg/kg in about 48 prevent toxicity.

If phenobarbital or benzos aren’t enough to manage autonomic symptoms (tachycardia, sweating, etc), think of dexmedetomidine or clonidine. But don’t use them alone...they don’t prevent seizures.

See our resource, Inpatient Alcohol Withdrawal, for more on thiamine, electrolytes, and other supportive care...and the role of alternative meds, such as gabapentin or ketamine.

Key References

  • J Addict Med. 2020 May/Jun;14(3S Suppl 1):1-72
  • J Am Coll Clin Pharm. 2022 Jun 24. doi: 10.1002/jac5.1674
  • Am J Emerg Med. 2011 May;29(4):382-5
  • J Emerg Med. 2013 Mar;44(3):592-598.e2
Hospital Pharmacist's Letter. September 2022, No. 380919

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