Phenobarbital for Alcohol Withdrawal Syndrome (AWS)
Chart Note (paste-as-is)
Assessment/Plan – Alcohol Withdrawal Syndrome: Patient with suspected/confirmed alcohol withdrawal exhibiting autonomic hyperactivity and agitation. High risk for complicated withdrawal given history of heavy alcohol use (DTs/seizures/prior ICU stay as applicable) and current clinical trajectory. We will use a phenobarbital-based protocol for GABAergic replacement and NMDA antagonism, aiming for light sedation with airway and hemodynamic safety.
- Targets: CIWA-Ar < 10 (if usable) or RASS 0 to –1; prevent seizures/DTs; avoid respiratory depression.
- Contraindications reviewed: severe hepatic failure, marked respiratory depression, porphyria, recent large benzodiazepine/opioid load. Risks/benefits discussed with team.
Phenobarbital Dosing (weight-based loading with monitored titration):
- Load: Total target 10–15 mg/kg IV (use Ideal Body Weight). Give initial 260 mg IV over 15–30 min, then 130–260 mg IV q30–60 min PRN to target (max cumulative 15 mg/kg).
- Maintenance (after clinical stabilization): Phenobarbital 60–120 mg PO/IV q12h × 24–48 h, then taper by 30–60 mg every 12–24 h over 2–4 days as symptoms allow.
- If combining with benzodiazepines: minimize/avoid co-administration; if needed for breakthrough, use reduced-dose lorazepam 0.5–1 mg IV PRN with close monitoring.
Monitoring/Safety:
- Continuous pulse oximetry and cardiorespiratory monitoring during loading and first night; q1h vitals until stable, then q2–4h.
- Neuro checks q1–2h during titration; hold further doses for RASS ≤ –2, RR < 10, SpO₂ < 92% on baseline O₂, or MAP < 65 mmHg.
- Basic labs: BMP/Mg/Phos now and in AM; consider ammonia/LFTs if hepatic disease suspected.
Adjuncts:
- Thiamine 100 mg IV before glucose (consider 200–500 mg IV if high Wernicke risk), plus folate and multivitamin.
- Fluids and electrolytes as needed; replete Mg/Phos aggressively for seizure prevention and refeeding risk.
- Consider clonidine or beta-blocker only for autonomic symptoms after adequate GABAergic coverage; avoid masking undertreatment.
Escalation/Rescue: If persistent agitation or seizures despite cumulative phenobarbital > 10–15 mg/kg, evaluate for alternate/complicating diagnoses (e.g., stimulants, head injury, infection, hepatic encephalopathy). Consider ICU sedation (e.g., propofol) with airway protection.
Disposition/Wean: Reduce to oral taper once symptom-controlled for 24 h; discontinue when CIWA-Ar remains < 8 without PRNs. Provide alcohol-cessation counseling, nutrition, and arrange addiction medicine follow-up.
Quick Orders (compact)
- Phenobarbital Load: 260 mg IV now (over 15–30 min); then 130–260 mg IV q30–60 min PRN to RASS 0 to –1 or CIWA < 10 (max total 15 mg/kg).
- Maintenance: 60–120 mg PO/IV q12h × 24–48 h, then taper by 30–60 mg per dose q12–24h over 2–4 days.
- Hold parameters: RASS ≤ –2, RR < 10, SpO₂ < 92% despite baseline O₂, MAP < 65.
- Adjuncts: Thiamine 100 mg IV before glucose; folate; MVI; Mg/Phos repletion protocols; IVF as needed.
- Monitoring: Telemetry + continuous pulse ox; vitals q1h during loading then q2–4h; BMP/Mg/Phos now and AM.
Weight-Based Loading Guide (Ideal Body Weight)
| IBW (kg) | 10 mg/kg (total) | 15 mg/kg (total) | Typical Split (examples) |
|---|---|---|---|
| 50 | 500 mg | 750 mg | 260 mg → 130–260 mg PRN to target |
| 60 | 600 mg | 900 mg | 260 mg → 130–260 mg PRN |
| 70 | 700 mg | 1050 mg | 260 mg → 130–260 mg PRN |
| 80 | 800 mg | 1200 mg | 260 mg → 130–260 mg PRN |
| 90 | 900 mg | 1350 mg | 260 mg → 130–260 mg PRN |
| 100 | 1000 mg | 1500 mg | 260 mg → 130–260 mg PRN |
Contraindications, Cautions, and Interactions
- Severe hepatic failure, significant respiratory depression, porphyria.
- Additive CNS/respiratory depression with benzodiazepines, opioids, propofol, ethanol, gabapentinoids.
- Enzyme induction (CYPs) may reduce efficacy of some meds over days; not usually acute-phase limiting.
- Consider dose reduction and slower titration in elderly, frail, or suspected OSA/COPD with CO₂ retention.
Operational Pearls
- Prefer phenobarbital-forward strategy when benzodiazepine-resistant or when prior very high benzo needs.
- Use one primary sedative strategy to avoid stacking sedatives; document a clear “hold” rule for the bedside nurse.
- Reassess for alternate diagnoses (trauma, infection, toxic co-ingestants) if unusually high doses are required.
