Can phenobarbital (every four times a day) be discontinued after 6 days, and should it be tapered (weaned) in a patient currently taking 65 milligrams four times daily (qid)?

From the Guidelines

I strongly advise against stopping phenobarbital abruptly after 6 days, and instead recommend a gradual taper to minimize the risk of withdrawal symptoms, as suggested by the most recent guidelines 1. When considering the management of barbiturates like phenobarbital, it's crucial to prioritize a gradual tapering approach to avoid acute withdrawal, which can lead to severe morbidity and potentially affect mortality and quality of life. The study from Mayo Clinic Proceedings in 2021 1 emphasizes the importance of not stopping barbiturates abruptly, especially if used long-term, to prevent withdrawal symptoms. Although the provided study does not specify the exact tapering schedule for phenobarbital, clinical practice typically involves reducing the daily dose by about 10-25% every 1-2 weeks. For a dose of 65 mg four times daily (260 mg daily), a possible reduction could be by approximately 30-65 mg per week. This could translate to decreasing the dose to 50 mg four times daily for one week, then to 40 mg four times daily the next week, and continuing this pattern until the medication is completely discontinued. It's essential to consult a healthcare provider to determine the most appropriate tapering schedule based on individual medical conditions and the duration of phenobarbital use. Given the long half-life of phenobarbital (approximately 80-120 hours), tapering is necessary even though the drug leaves the body slowly, especially at higher doses. Therefore, it's critical to contact a healthcare provider to develop a personalized weaning schedule rather than attempting to stop the medication independently. Key considerations include:

• Gradual tapering to avoid withdrawal symptoms
• Individualized tapering schedule based on medical condition and duration of use
• Close monitoring by a healthcare provider
• Avoiding abrupt cessation to prevent severe morbidity and potential impacts on mortality and quality of life.

From the FDA Drug Label

The symptoms of barbiturate withdrawal can be severe and may cause death. Minor withdrawal symptoms may appear 8 to 12 hours after the last dose of a barbiturate These symptoms usually appear in the following order: anxiety, muscle twitching, tremor of hands and fingers, progressive weakness, dizziness, distortion in visual perception, nausea, vomiting, insomnia and orthostatic hypotension. Major withdrawal symptoms (convulsions and delirium) may occur within 16 hours and last up to 5 days after abrupt cessation of these drugs Treatment of barbiturate dependence consists of cautious and gradual withdrawal of the drug 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 After stabilization on phenobarbital, the total daily dose is decreased by 30 mg a day as long as withdrawal is proceeding smoothly.

No, we should not stop phenobarbital after 6 days without weaning.

• The patient is currently on 65 mg qid, which is a significant dose.
• Abrupt cessation of phenobarbital can lead to severe withdrawal symptoms, including convulsions and delirium.
• A gradual withdrawal regimen is recommended, with a decrease in dosage by 30 mg a day as long as withdrawal is proceeding smoothly 2.
• Weaning should be done cautiously to avoid severe withdrawal symptoms 2.

From the Research

Stopping Phenobarbital After 6 Days

• The decision to stop phenobarbital after 6 days depends on various factors, including the patient's medical history, current condition, and the reason for taking the medication 3, 4.
• There is limited data on the safety of discontinuing antiseizure drugs, including phenobarbital, after a short period of use 4.
• One study suggests that weaning from antiseizure drugs after new onset status epilepticus can be done, but the risk of seizure recurrence is higher in patients with refractory status epilepticus treated with barbiturates 4.

Weaning from Phenobarbital

• Weaning from phenobarbital is recommended to avoid withdrawal symptoms, but the optimal tapering schedule is not well established 5.
• A case report describes a successful outpatient taper of phenobarbital therapy, but the details of the tapering schedule are not provided 5.
• Another study suggests that a gradual taper of phenobarbital can be done, but the risk of withdrawal seizures is still present 3.

Current Dosage and Weaning

• The current dosage of 65 mg qid is relatively high, and weaning should be done cautiously to avoid withdrawal symptoms 3, 5.
• There is no clear guidance on the optimal weaning schedule for phenobarbital, but a gradual taper over several days or weeks is recommended 3, 5.
• The risk of seizure recurrence during weaning from phenobarbital is higher in patients with refractory status epilepticus treated with barbiturates 4.