This medication is a Schedule II drug.
Common Brand Names: Nembutal
Therapeutic Class: Barbiturate anticonvulsant
Common Injectable Dosage Forms:
Solution for Injection: 50 mg/mL (20 mL, 50 mL)
Children aged 5-12: 2 mg/kg by IV route 5-10 minutes before procedure. May repeat once.
Adults: 100 mg IV prior to procedure.
Children: Start with a loading dose of 5-15 mg/kg given slowly over 1-2 hours. Maintenance infusion is 0.5-5 mg/kg/hour.
Adults: Start with a loading dose of 2-15 mg/kg given over 1-2 hours. Maintenance infusion is 0.5-3 mg/kg/hour.
Hypnotic: 150-200 mg by IM route, 100 mg by IV route, repeated every 1-3 minutes up to 200-500 mg total dose.
Administration and Stability:
Pentobarbital may be administered via deep IM or slow IV injection. No more than 5 mL (250 mg) may be given IM at one site. IV push doses can be given undiluted but should be administered no faster than 50 mg/minute. Parenteral solutions are highly alkaline and when mixed with an acidic solution, a precipitate may form.
Pharmacology/Pharmacokinetics:
Pentobarbital is a short-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. Onset of action is 10-15 minutes by IM route and approximately 1 minute by IV route. Duration of action is about 15 minutes and half-life elimination is 22-25 hours.
Drug and Lab Interactions:
Pentobarbital is a strong inducer of CYP3A4 and CYP2A6 enzymes. When combined with other CNS depressants, ethanol, opioid analgesics, antidepressants, or benzodiazepines, additive respiratory and CNS depression may occur. Phenobarbital may decrease the effects of oral contraceptives, benzodiazepines, calcium channel blockers, rifampin, and venlafaxine. Barbiturates may also enhance the metabolism of methadone, resulting in methadone withdrawal symptoms.
Contraindications/Precautions:
Contraindicated in patients with hypersensitivity to pentobarbital or other barbiturates. Use with caution in patients with hepatic impairment, dyspnea, porphyria, and pregnancy. Use caution in patients who are hemodynamically unstable. Pregnancy Category D.
Monitoring Parameters:
Respiratory status, cardiovascular status; cardiac monitor and blood pressure monitor may be required.
Adverse Effects:
Possible side effects include bradycardia, hypotension, syncope, drowsiness, headache, insomnia, hallucinations, Stevens-Johnson syndrome, nausea/vomiting, constipation, and hematologic changes.
Common Clinical Applications:
Used as a sedative or hypnotic, as a preanesthetic, and for high-dose barbiturate coma for treatment in patients with increased intracranial pressure or status epilepticus unresponsive to other therapy.
