Evaluation of Phenobarbital Serum Levels on Clinical Outcomes for the Treatment of Severe Alcohol Withdrawal Syndrome in a Medical Intensive Care Unit

Background: Optimal phenobarbital serum levels for treating severe alcohol withdrawal syndrome (AWS) remain unclear. Objective: This study evaluated whether phenobarbital serum levels are associated with symptom control in patients with severe AWS admitted to a medical intensive care unit (MICU). Methods: We conducted a single-center, retrospective analysis of adult MICU patients treated with phenobarbital for severe AWS between January 2011 and December 2022. Patients were categorized into two cohorts based on symptom control status: (1) symptom controlled and (2) non-symptom controlled. The primary objective was to assess the relationship between phenobarbital serum levels and symptom control. Secondary objectives evaluated dosing regimens and safety outcomes. Results: Of 114 patients (63 symptom controlled, 51 non-symptom controlled), no significant association was found between phenobarbital levels (32.2 ± 19.9 vs 36.9 ± 16.0 mcg/mL) (mean, SD) and symptom control (P = 0.08). Phenobarbital dosing regimen, loading dose (LD) ± as needed (PRN) doses (n = 49) vs PRN only (n = 65), was not significantly associated with MICU LOS (P = 0.09). However, treatment duration was shorter in the PRN only group (median 54 vs 97 hours; P = 0.016). Endotracheal intubation and vasopressor use were more common in non-symptom controlled patients. No mortality occurred in either group. Conclusion: No significant evidence was found to suggest that phenobarbital serum levels were associated with symptom control in patients admitted to a MICU for severe AWS as defined in this study.