Phenobarbital
Classification
HIGH-ALERT MEDICATION
- Anticonvulsant; barbiturate
Indications
CCP: Treatment of refractory status epilepticus
Contraindications
- Hypersensitivity to phenobarbital, barbiturates, or any component of the formulation
- Marked hepatic impairment
- Porphyria
- Nephritic patients (large doses)
- Dyspnea or airway obstruction
- Intra-arterial or SubQ administration
- Use in patients with a history of sedative/hypnotic substance use disorder
Adult dosages
CCP: Refractory status epilepticus
- 15 mg/kg IV
Pediatric Considerations And Dosing
CCP: Refractory status epilepticus
- 15 mg/kg, maximum 1000 mg
Mechanism Of Action
- Long-acting barbiturate with sedative, hypnotic, and anticonvulsant properties. Barbiturates depress the sensory cortex, decrease motor activity, alter cerebellar function, and produce drowsiness, sedation, and hypnosis. In high doses, barbiturates exhibit anticonvulsant activity; barbiturates produce dose-dependent respiratory depression.
Pharmacokinetics
- IV:
- Onset - 5 minutes
- Peak - 15 minutes
- Duration - 3-4 hours
Adverse Effects
- Cardiovascular: Bradycardia, hypotension, syncope, thrombophlebitis (IV)
- Central nervous system: Agitation, anxiety, ataxia, central nervous system stimulation, central nervous system depression, confusion, dizziness, drowsiness, hallucination, hangover effect, headache, impaired judgement, insomnia, lethargy, nervousness, nightmares
- Dermatologic: Exfoliative dermatitis, skin rash, Stevens-Johnson syndrome
- Gastrointestinal: Constipation, nausea, vomiting
- Genitourinary: Oliguria
- Hematologic & oncologic: Agranulocytosis, thrombocytopenia, megaloblastic anemia
- Local: Pain at injection site
- Neuromuscular & skeletal: Hyperkinesia, laryngospasm
- Respiratory: Apnea (especially with rapid IV use), hypoventilation, respiratory depression
Warning And Precautions
- CNS depression: May cause CNS depression which may impair physical or mental abilities; patients must be cautioned about performing tasks which require mental alertness
- Hypersensitivity: Exfoliative dermatitis and Stevens-Johnson syndrome, possibly fatal, may occur; discontinue if dermatological reactions occur
- Paradoxical stimulatory response: May cause paradoxical responses, including agitation and hyperactivity, particularly in patients with acute or chronic pain, and pediatric patients
- Respiratory depression: May cause respiratory depression particularly when administered intravenously; use with caution in patients with respiratory disease
Drug Interactions
- Depressant effects are potentiated by the presence of other CNS depressants such as alcohol, sedatives, antihistaminics, or psychotropic drugs
- Patients on neuroleptics: Morphine may increase the risk of respiratory depression, hypotension, and profound sedation or coma