Reviewed on 9/8/2021

What Is Pentobarbital and How Does It Work?

Pentobarbital is a barbiturate that acts as a depressant, or sedative, used short-term to treat insomnia. Pentobarbital is also used as an emergency treatment for seizures, and to cause patients to fall asleep for surgery.

Pentobarbital is available under the following different brand names: Nembutal.

Dosages of Pentobarbital

Adult and Pediatric Dosage Forms and Strengths

Injectable solution: Schedule II

  • 50 mg/mL

Dosage Considerations – Should be Given as Follows:



  • Adult, Initial: 100 mg intravenously (IV) OR 150-200 mg intramuscularly (IM)
  • May give small increments of drug after at least 1 minute to reach full effect
  • Not to exceed 500 mg
  • Pediatric: 2-6 mg/kg IM once; not to exceed 100 mg

Barbiturate Coma

  • Load: 10-15 mg/kg intravenously (IV) over 30 min; follow by 5 mg/kg IV every 1 hour for 3 doses
  • Maintenance: 1 mg/kg/hour IV; may increase to 2-4 mg/kg/hour

Renal Failure

  • Use lower dose

Hepatic Failure

  • Use lower dose

Pre-procedure Sedation, Pediatric

  • 2-6 mg/kg intramuscularly (IM), OR
  • 1-3 mg/kg intravenously (IV)
  • Not to exceed 100 mg IM

Other Indications and Uses

  • Acute convulsive episodes

Dosing Considerations

  • Geriatric: Not recommended; use lower dose if use becomes necessary


What Is Epilepsy? Symptoms, Causes, and Treatments See Slideshow

What Are Side Effects Associated with Using Pentobarbital?

Common side effects of pentobarbital include:

Serious side effects of Nembutal such as:

  • Hallucinations
  • Weak or shallow breathing
  • Slow heart rate
  • Weak pulse
  • Feeling like you might pass out

This is not a complete list of side effects and other serious side effects may occur. Call your doctor for information and medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What Other Drugs Interact with Pentobarbital?

If your doctor has directed you to use this medication, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider or pharmacist first.

  • Pentobarbital has no known severe interactions with other drugs.
  • Severe interactions of pentobarbital include:
    • artemether/lumefantrine
    • cariprazine
    • cobimetinib
    • daclatasvir
    • dienogest/estradiol valerate
    • elbasvir/grazoprevir
    • elvitegravir/cobicistat/emtricitabine/tenofovir DF
    • lumacaftor/ivacaftor
    • lumefantrine
    • lurasidone
    • naloxegol
    • ombitasvir/paritaprevir/ritonavir
    • ombitasvir/paritaprevir/ritonavir and dasabuvir
    • panobinostat
    • praziquantel
    • regorafenib
    • roflumilast
    • sodium oxybate
    • vandetanib
  • Pentobarbital has serious interactions with at least 85 different drugs.
  • Pentobarbital has moderate interactions with at least 341 different drugs.
  • Pentobarbital has mild interactions with at least 126 different drugs.

This document does not contain all possible interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share the list with your doctor and pharmacist. Check with your physician if you have health questions or concerns.


If you have had a seizure, it means you have epilepsy. See Answer

What Are Warnings and Precautions for Pentobarbital?


This medication contains pentobarbital. Do not take Nembutal if you are allergic to pentobarbital or any ingredients contained in this drug.

Keep out of reach of children. In case of overdose, get medical help or contact a Poison Control Center immediately.


Effects of Drug Abuse

  • None

Short-Term Effects

  • See "What Are Side Effects Associated with Using Pentobarbital?"

Long-Term Effects

  • See "What Are Side Effects Associated with Using Pentobarbital?"


General anesthetics and sedation drugs in young children and pregnant women

Brain development

  • Prolonged or repeated exposure may result in negative effects on fetal or young children's brain development
  • Caution with use during surgeries or procedures in children younger than 3 years or in pregnant women during their third trimester
  • Assess the risk:benefit ratio in these populations, especially for prolonged procedures (i.e., greater than 3 hours) or multiple procedures

Pregnancy and Lactation

Do not use pentobarbital in pregnancy. The risks involved outweigh potential benefits. Safer alternatives exist.

Use pentobarbital during pregnancy only in LIFE-THREATENING emergencies when no safer drug is available. There is positive evidence of human fetal risk.

Pentobarbital is secreted in breast milk; use caution if breastfeeding.


Medscape. Pentobarbital.
RxList. Nembutal.

Health Solutions From Our Sponsors