Pentobarbital (injection)

Generic name: pentobarbital (injection) [ PEN-toe-BAR-bi-tal ]
Brand names: Nembutal, Nembutal Sodium
Dosage form: injectable solution (50 mg/mL)
Drug class: Barbiturates

Medically reviewed by Drugs.com on Apr 9, 2024. Written by Cerner Multum.

What is pentobarbital?

Pentobarbital is used short-term to treat insomnia, or to cause you to fall asleep for surgery.

Pentobarbital is also used as an emergency treatment for seizures.

Pentobarbital may also be used for purposes not listed in this medication guide.

Pentobarbital side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Pentobarbital may cause serious side effects. Call your doctor at once if you have:

• confusion, agitation, hallucinations;

• weak or shallow breathing;

• slow heart rate, weak pulse; or

• a light-headed feeling, like you might pass out.

Side effects such as confusion, depression, or excitement may be more likely in older adults and those who are ill or debilitated.

Common side effects of pentobarbital may include:

• drowsiness, dizziness;

• loss of balance or coordination;

• nausea, vomiting, constipation;

• overactive reflexes;

• sleep problems (insomnia), nightmares; or

• feeling restless or excited (especially in children or older adults).

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

Warnings

You should not use phenobarbital if you have severe liver disease or a history of addiction to drugs similar to phenobarbital.

Before taking this medicine

You should not use pentobarbital if you are allergic to it, or if you have:

• a history of porphyria (a genetic enzyme disorder that causes symptoms affecting the skin or nervous system).

Tell your doctor if you have ever had:

• liver disease;

• kidney disease;

• temporary or chronic pain; or

• an addiction to phenobarbital or similar medicines.

Pentobarbital may harm an unborn baby. If you use pentobarbital during pregnancy, your baby could be born with life-threatening withdrawal symptoms, and may need medical treatment for several weeks.

Phenobarbital can make birth control pills less effective. Ask your doctor about using a non-hormonal birth control (condom, diaphragm with spermicide) to prevent pregnancy.

Sedatives used during surgery may affect brain development in a young child or unborn baby (when used in the mother), leading to learning or behavior problems later in life. Long surgeries or repeated procedures pose the highest risks.

Ask a doctor if it is safe to breastfeed shortly after you receive pentobarbital.

How is pentobarbital given?

Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.

Pentobarbital may be habit-forming. Never share pentobarbital with another person, especially someone with a history of drug abuse or addiction. Keep the medication in a place where others cannot get to it. Selling or giving away this medicine is against the law.

Pentobarbital is injected into a muscle, or into a vein through an IV. A healthcare provider will usually give you this injection.

You may be shown how to use pentobarbital at home. Do not give yourself this medicine if you do not understand how to use the injection and properly dispose of needles, IV tubing, and other items used.

When injected into a vein, pentobarbital must be given slowly.

Your breathing, blood pressure, oxygen levels, kidney function, and other vital signs will be watched closely after you receive pentobarbital in a hospital setting.

Do not use pentobarbital if it has changed colors or has particles in it. Call your pharmacist for new medication.

Do not reuse a needle or syringe. Place them in a puncture-proof "sharps" container and dispose of it following state or local laws. Keep out of the reach of children and pets.

If you use this medicine long-term, you may need frequent medical tests.

Do not stop using this medicine suddenly after long-term use, or you could have unpleasant withdrawal symptoms. Ask your doctor how to safely stop using pentobarbital.

Store at room temperature away from moisture and heat. Do not freeze.

What happens if I miss a dose?

Since pentobarbital is often used only when needed, you may not be on a dosing schedule. If you are on a schedule, use the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not use extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention if you think you have used too much of pentobarbital. An overdose of pentobarbital can be fatal.

What should I avoid while using pentobarbital?

Pentobarbital can cause side effects that may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be awake and alert.

Do not drink alcohol. Dangerous side effects can occur when alcohol is combined with pentobarbital.

What other drugs will affect pentobarbital?

Using pentobarbital with other drugs that slow your breathing can cause dangerous side effects or death. Ask your doctor before using opioid medication, a sleeping pill, a muscle relaxer, or medicine for anxiety or seizures.

Tell your doctor about all your current medicines. Many drugs can affect pentobarbital, especially:

• doxycycline;

• griseofulvin;

• birth control pills or hormone replacement estrogens;

• a blood thinner--warfarin, Coumadin, Jantoven;

• an MAO inhibitor--isocarboxazid, linezolid, methylene blue injection, phenelzine, tranylcypromine, and others;

• other seizure medications--divalproex, phenytoin, valproic acid; or

• steroid medicine--prednisone, dexamethasone, prednisolone, and others.

This list is not complete and many other drugs may affect pentobarbital. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Medical Disclaimer

Copyright 1996-2024 Cerner Multum, Inc. Version: 7.02.