Adjunctive Phenobarbital for Alcohol Withdrawal Syndrome: A Focused Literature Review

Pharmacokinetic analysis of a phenobarbital overdose treated with urinary alkalinization alone

Phenobarbital is a long-acting barbiturate used to treat alcohol withdrawal and epilepsy. Acute overdoses present with varying levels of central nervous system depression and large overdoses can be life threatening. Phenobarbital is an attractive candidate for enhanced elimination using urinary alkalinization given it is a weak acid with a long half-life and extensive urinary elimination. Limited human data exist regarding use of urine alkalinization for the treatment of phenobarbital overdose. We present a fourteen-year-old female who was treated with urinary alkalinization alone following an intentional ingestion of 3800 mg (84.4 mg/kg) of phenobarbital tablets. Urine drugs of abuse screening was preliminary positive for barbiturates and confirmed to be phenobarbital only. The initial serum phenobarbital concentration, drawn nine hours post-ingestion, was 97.4 mcg/ml (normal range 15-40 mcg/ml). Urinary alkalinization with sodium bicarbonate was started approximately 12 h post-ingestion and stopped at 72 h post-ingestion; clinical toxicity resolved by hospital day 5. The infusion was titrated to a urinary pH of greater than 7.5. Serial serum and urine phenobarbital measurements were obtained to determine elimination half-life and urinary excretion. The elimination half-life while undergoing urinary alkalinization was 81.3 h. Prior to initiation of urinary alkalinization, the urine phenobarbital concentration was 37 mcg/ml. Approximately 8.75 h after initiation, it was greater than 200 mcg/ml at a urine pH of 8.5. Urinary alkalinization appeared to augment urinary phenobarbital excretion, though with no discernible effect on elimination half-life and unclear clinical benefit. Further research is needed to better characterize the clinical effects of urinary alkalinization for phenobarbital overdose.

Evaluation of phenobarbital dosing strategies for hospitalized patients with alcohol withdrawal syndrome

OBJECTIVE

Alcohol remains the fourth‑leading preventable cause of death in the U.S. The objective of this study was to compare the incidence of phenobarbital (PHB)-resistant withdrawal and determine risk factors for PHB-resistant alcohol withdrawal syndrome (AWS).

METHODS

This retrospective cohort study included adults admitted to an academic center with AWS who received PHB as part of an institution-specific treatment protocol. The primary outcome was incidence of AWS resistant to initial protocolized PHB load across two cohorts (standard-dose, 10 mg/kg vs. low-dose, 6 mg/kg).

RESULTS

Among 176 included patients, there was no difference in the incidence of PHB-resistant AWS based on initial PHB load [low-dose load, 21 (18.3%) vs. standard-dose load, 12 (19.7%), p = 0.82]. There were also no differences in observed PHB-related ADEs between the groups. Total benzodiazepine dose received (mg) in the 24 h prior to initial PHB load was the only risk factor significantly associated with AWS resistant to initial protocolized PHB load [adjusted OR 1.79 (95% CI 1.24, 2.60)]. PHB-resistant withdrawal occurred in 33 (18.8%) patients with a median cumulative PHB dose of approximately 20 mg/kg during hospitalization.

CONCLUSION(S)

There were no differences in the incidence of PHB-resistant AWS or PHB-related ADEs based on initial PHB loading dose.

Phenobarbital for alcohol withdrawal in the context of the opioid epidemic: a neglected caveat

Phenobarbital interacts with the mortality-reducing opioid agonist therapies buprenorphine and methadone, risking delayed opioid withdrawal and relapse when administered concurrently. With increased adoption of phenobarbital into alcohol withdrawal protocols there should be safeguards in place to—in most cases—avoid phenobarbital for patients with a concurrent opioid use disorder.

Current evidence and clinical utility of phenobarbital for alcohol withdrawal syndrome

BACKGROUND

Phenobarbital (PB) has been acknowledged among clinicians as a potential alternative to benzodiazepines (BZD) to decrease the need for hospital length of stay and complications associated with alcohol withdrawal syndrome (AWS). However, the level of evidence, including appropriate dosing, is unclear. We aim to summarize the evidence regarding PB used in AWS and provide future agendas for research.

METHODS

Following the PRISMA guidelines, we searched MEDLINE, EMBASE, ClinicalTrials.gov, and WHO ICTRP for all peer-reviewed articles and clinical trials using keywords including"alcohol withdrawal", "delirium tremens", "phenobarbital," and "barbiturate" from their inception to September 18, 2022.

RESULTS

We included 20 articles, nine in the emergency department (ED) and 11 in the general floors or intensive care units (ICUs). Studies performed in the ED included two RCTs, although both suffered from a considerably small sample size. Six studies done in the general floors or ICUs compared PB and BZD monotherapy, while four compared the utility of adjunct PB in addition to BZD compared with BZD monotherapy and one was a database study without specific dosing information. Overall, there was considerable heterogeneity in PB dosing, measured outcomes, and AWS severity measurement scales.

CONCLUSION

This systematic review summarizes the current evidence related to PB use in AWS. While considerable heterogeneity exists among studies available, PB as monotherapy without BZD may be a safe and effective alternative in AWS treatment. Future prospective studies or trials should focus on the standardization of PB dosing and outcomes.

Symptoms-triggered approach versus fixed-scheduled approach of benzodiazepines for management of alcohol withdrawal syndrome: Non-randomized controlled trial

BACKGROUND

Alcohol withdrawal syndrome, if untreated, can lead to potentially life-threatening complications. Benzodiazepines are the drugs of choice for the treatment of alcohol withdrawal syndrome. We aimed to compare the symptoms-triggered approach and fixed-dose approach of benzodiazepine administration for treatment of alcohol withdrawal syndrome in regard to the health care utilization measured by the total dose of benzodiazepines, length of hospital stays, and 90-day readmissions rate.

METHODS

A single-center prospective non-randomized controlled trial included all patients diagnosed with alcohol withdrawal syndrome. The group of patients admitted between October 1, 2019, and September 30, 2020, were treated with the fixed-scheduled approach (n = 150), while all patients admitted between November 1, 2020, to October 31, 2021, were treated with the symptoms-trigger approach (n = 50).

RESULTS

The fixed-dose approach group showed a significant higher 90-day readmissions rate (HR: 2.61; 95% CI = 1.18, 6.84; p = 0.01). Kaplan-Meier survival analysis showed a significantly shorter duration to the first readmission in the fixed-scheduled approach group (HR: 2.3; 95% CI = 5.6, 1.16; p = 0.02). The symptoms-triggered approach group required a significantly lower dose of diazepam (40 mg vs. 10 mg; p < 0.01) and a higher dose of thiamine (800 mg vs. 600 mg; p < 0.01). Length of hospital stay was significantly increased in the symptoms-triggered approach group (3.9 vs. 2.2 days; p < 0.01).

DISCUSSION

The use of a symptoms-triggered approach to treat alcohol withdrawal syndrome was associated with a lower 90-day readmission rate, prolonged period to the first readmission, and reduced total dose of benzodiazepines, but longer length of hospital stays.

CONCLUSION

The symptoms-triggered approach is safe, cost-effective, and associated with reduced alcohol dependence relapse.

Phenobarbital and Alcohol Withdrawal Syndrome: A Systematic Review and Meta-Analysis

Alcohol withdrawal syndrome (AWS) is a complication frequently encountered among patients who are chronic alcohol abusers. It is considered to have a significant impact on the United States healthcare system. It not only has a toll on the healthcare spending but also contributes to significant morbidity and mortality. Benzodiazepines are considered first line in the treatment of AWS. Since patients with alcohol use disorder have downregulated gamma aminobutyric acid (GABA) receptors, this often leads to benzodiazepine resistance. Phenobarbital is also used in the management of alcohol withdrawal syndrome. Here we present a systematic review and meta-analysis of the efficacy and safety of the drug. We conducted an electronic database search for relevant studies published between the inception of the project and November 20, 2022, in three databases, including Medline/PubMed, Embase, and Cochrane Library. Our study included all original studies with prime focus on the baseline characteristics of patients admitted to the intensive care unit (ICU) for alcohol withdrawal syndrome and management/monitoring protocol implemented for its treatment. The primary outcomes that were the focus of our study consisted of changes in the length of hospital stay, length of ICU stay, and changes in scoring systems (for alcohol withdrawal assessment and monitoring) following the implementation of phenobarbital. The secondary outcomes included complications such as intubation and mortality. Based on our analysis, the mean difference in hospital stay was statistically significant at -2.6 (95% CI, -4.48, -0.72, P=0.007) for phenobarbital compared to the benzodiazepine group. We were unable to comment on the heterogeneity in our meta-analysis due to the standard deviation not being reported in one study. There was no statistically significant difference regarding the length of stay in the intensive care unit compared to the control/comparative arm, with a mean difference of -1.17 (95% CI, -1.17, 0.09, P=0.07), with considerable heterogeneity (I²=77%, P=0.002). Our meta-analysis also investigated the risk of intubation between the phenobarbital and the control/comparative group. There was statistically significant difference in the incidence of intubation, relative risk (RR) 0.52 (95% CI, 0.25, 1.08, P=0.08), with considerable heterogeneity (I²=80%, P=0.0001). Our study concludes that phenobarbital is an effective tool in the management of AWS in an ICU setting. However, various studies have reported contradictory results, and vital information appears to be lacking. Moreover, there is a lack of uniformity in terms of phenobarbital dosing. Drug administration should be adapted according to the severity of the symptoms. Further studies need to be conducted discussing the safety profile and adverse effects of the drug when it comes to the management of alcohol withdrawal syndrome.