From the FDA Drug Label
The total daily amount of phenobarbital is then administered in 3 to 4 divided doses, not to exceed 600 mg daily. One method involves substituting a 30 mg dose of phenobarbital for each 100 to 200 mg dose of barbiturate that the patient has been taking Should signs of withdrawal occur on the first day of treatment, a loading dose of 100 to 200 mg of phenobarbital may be administered IM in addition to the oral dose After stabilization on phenobarbital, the total daily dose is decreased by 30 mg a day as long as withdrawal is proceeding smoothly.
The dosing for Phenobarbital in alcohol withdrawal is not directly stated, but for barbiturate withdrawal, the dose can be substituted with 30 mg of phenobarbital for each 100 to 200 mg dose of barbiturate, with a total daily dose not to exceed 600 mg daily, administered in 3 to 4 divided doses. A loading dose of 100 to 200 mg may be given if withdrawal symptoms occur. The dose is then decreased by 30 mg daily as long as withdrawal proceeds smoothly 1.
From the Research
Phenobarbital can be used for alcohol withdrawal, typically starting with a loading dose of 10-15 mg/kg (approximately 200-400 mg) given intravenously or orally, followed by additional doses of 100-200 mg every 1-2 hours until symptoms are controlled or a maximum daily dose of 600-800 mg is reached, as supported by the most recent study 2. For maintenance, 30-60 mg can be given 2-3 times daily, with gradual tapering over 3-7 days. Monitoring is essential, including vital signs, withdrawal symptoms using the CIWA-Ar scale, and sedation level. Phenobarbital works by enhancing GABA activity in the brain, similar to alcohol's mechanism, which helps prevent withdrawal symptoms like seizures and delirium tremens. It has a long half-life (80-120 hours), allowing for less frequent dosing and smoother withdrawal. Caution is needed in patients with respiratory depression, liver disease, or when combined with other CNS depressants. Supportive care including IV fluids, thiamine, folate, and multivitamins should accompany phenobarbital treatment for alcohol withdrawal.
Some key points to consider when using phenobarbital for alcohol withdrawal include:
- The potential for decreased risk of respiratory complications compared to benzodiazepines, as shown in a study 3
- The importance of monitoring for signs of overdose, such as respiratory depression, and adjusting the dose accordingly
- The need for gradual tapering of the dose to prevent rebound withdrawal symptoms
- The potential for interactions with other medications, such as CNS depressants, and the need for careful monitoring and adjustment of the dose
Overall, phenobarbital can be a safe and effective treatment option for alcohol withdrawal, particularly in patients who are at risk of severe withdrawal symptoms or who have not responded to benzodiazepine treatment, as supported by studies 2, 4, 5.