Health Library

Pentobarbital (Into the rectum)

Pentobarbital (pen-toe-BAR-bi-tal)

Treats insomnia (trouble sleeping), and helps you relax. This medicine is a barbiturate.

Brand Name(s):

When This Medicine Should Not Be Used:

How to Use This Medicine:

Suppository

• Your doctor will tell you how much medicine to use. Do not use more than directed.
• Never take rectal suppositories by mouth.
• Pentobarbital is not for long-term use. If you are using this medicine for insomnia, use it only at bedtime.
• Wash your hands with soap and water before and after using this medicine. Remove the foil or wrapper from the suppository before inserting it.
• To make the suppository easier to insert, wet it with a small amount of warm water. You may also use a lubricating gel such as K-Y® Jelly, but do not use petroleum jelly (Vaseline®).
• Lie on your left side with your left leg straight or slightly bent, and your right knee bent upward. Gently push the pointed end of the suppository into the rectum about 1 inch.
• Keep lying down for about 15 minutes to keep the suppository from coming out before it melts. Then, wash your hands again.
• Never share your medicine with anyone.

How to Store and Dispose of This Medicine:

• You may store the suppositories in the refrigerator, but do not freeze them.
• Ask your pharmacist, doctor, or health caregiver about the best way to dispose of any outdated medicine or medicine no longer needed.
• Keep all medicine out of the reach of children. Never share your medicine with anyone.

Drugs and Foods to Avoid:

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

• Make sure your doctor knows if you are also using blood thinners (Coumadin®), corticosteroids (cortisone, prednisone), griseofulvin (Grifulvin®), doxycycline (Vibramycin®), medicine for seizures (such as Depakote®, Dilantin®), MAO inhibitors (Eldepryl®, Marplan®, Nardil®, Parnate®), or hormones (including birth control pills).
• Tell your doctor if you use anything else that makes you sleepy. Some examples are allergy medicine, narcotic pain medicine, and alcohol.
• Do not drink alcohol while you are using this medicine.

Warnings While Using This Medicine:

• It is not safe to take this medicine during pregnancy. It could harm an unborn baby. Tell your doctor right away if you become pregnant.
• Make sure your doctor knows if you are breastfeeding, or if you have liver disease, kidney disease, food or drug allergies, a history of alcohol or drug abuse, or have any health problems that cause pain.
• Tell your doctor if you feel depressed or have thoughts of suicide.
• This medicine may cause a serious type of allergic reaction called anaphylaxis. Anaphylaxis can be life-threatening and requires immediate medical attention. Stop taking this medicine and call your doctor right away if you have itching, hives, trouble breathing, or any swelling of your hands, face, or mouth when you take this medicine.
• This medicine may make you dizzy or drowsy. Avoid driving, using machines, or doing anything else that could be dangerous if you are not alert. This medicine may also cause sleep-related behaviors such as sleep-driving, making phone calls, or preparing and eating food while asleep or not fully awake. If these reactions occur, tell your doctor right away.
• This medicine can be habit-forming. Do not use more than your prescribed dose. Call your doctor if you think your medicine is not working.
• Using too much of this medicine can cause serious breathing problems. Symptoms of an overdose include: Extreme dizziness or fainting, shortness of breath or shallow breathing, fast heartbeat, and low body temperature.
• Do not stop using this medicine suddenly. Your doctor will need to slowly decrease your dose before you stop it completely.
• If you have any of these symptoms after you stop using pentobarbital, call your doctor right away: Anxiety, trembling or twitching, weakness, trouble seeing, dizziness, confusion, or seizures.

Possible Side Effects While Using This Medicine:

Call your doctor right away if you notice any of these side effects:

• Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
• Muscle weakness or uncontrolled body movements.
• Slow heartbeat.
• Trouble breathing.
• Unusual thoughts or behavior, confusion, or hallucinations.
• Yellowing of your skin or the whites of your eyes.

If you notice these less serious side effects, talk with your doctor:

• Dizziness or lightheadedness.
• Mild fever.
• Nausea, vomiting, or constipation.

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088

Last Updated: 9/6/2024