Medical Editor: John P. Cunha, DO, FACOEP
Nembutal (pentobarbital sodium) is a barbiturate that acts as a depressant, or sedative, used short-term to treat insomnia. Nembutal is also used as an emergency treatment for seizures, and to cause patients to fall asleep for surgery. Nembutal is available in generic form. Common side effects of Nembutal include:
- problems with memory or concentration,
- aggression (especially in children or older adults),
- loss of balance or coordination,
- "hangover" effect (drowsiness the day after a dose),
- low blood pressure,
- injection site reactions, or
- skin rash.
Seek medical attention immediately if you suffer from any serious side effects of Nembutal such as:
- weak or shallow breathing,
- slow heart rate,
- weak pulse, or
- feeling like you might pass out.
Dosage of Nembutal is determined by the patient's age, weight, and condition. Nembutal may interact with other medications, including blood thinners, doxycycline, other seizure medications, MAO inhibitors, griseofulvin, birth control pills, hormone replacement estrogens, or steroids. Tell your doctor all medications you are taking. Do not use Nembutal if you are pregnant. It could harm a fetus. Nembutal may cause addiction or withdrawal symptoms in a newborn if the mother uses the medication during pregnancy. Nembutal can pass into breast milk and may harm a nursing baby. Do not use this medication without telling your doctor if you are breastfeeding. Nembutal may be habit-forming. Do not stop using Nembutal suddenly after using it long-term, or you could have withdrawal symptoms.
Our Nembutal Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.
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.
Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
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 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).
Read the entire detailed patient monograph for Nembutal (Pentobarbital)
The following adverse reactions and their incidence were compiled from surveillance of thousands of hospitalized patients. Because such patients may be less aware of certain of the milder adverse effects of barbiturates, the incidence of these reactions may be somewhat higher in fully ambulatory patients.
Less than 1 in 100 patients. Adverse reactions estimated to occur at a rate of less than 1 in 100 patients listed below, grouped by organ system, and by decreasing order of occurrence are:
Digestive system: Nausea, vomiting, constipation.
Other reported reactions: Headache, injection site reactions, hypersensitivity reactions (angioedema, skin rashes, exfoliative dermatitis), fever, liver damage, megaloblastic anemia following chronic phenobarbital use.
Drug Abuse And Dependence
Barbiturates may be habit forming. Tolerance, psychological dependence, and physical dependence may occur especially following prolonged use of high doses of barbiturates. Daily administration in excess of 400 milligrams (mg) of pentobarbital or secobarbital for approximately 90 days is likely to produce some degree of physical dependence. A dosage of from 600 to 800 mg taken for at least 35 days is sufficient to produce withdrawal seizures. The average daily dose for the barbiturate addict is usually about 1.5 grams. As tolerance to barbiturates develops, the amount needed to maintain the same level of intoxication increases; tolerance to a fatal dosage, however, does not increase more than two-fold. As this occurs, the margin between an intoxicating dosage and fatal dosage becomes smaller.
Symptoms of acute intoxication with barbiturates include unsteady gait, slurred speech, and sustained nystagmus. Mental signs of chronic intoxication include confusion, poor judgment, irritability, insomnia, and somatic complaints.
Symptoms of barbiturate dependence are similar to those of chronic alcoholism. If an individual appears to be intoxicated with alcohol to a degree that is radically disproportionate to the amount of alcohol in his or her blood the use of barbiturates should be suspected. The lethal dose of a barbiturate is far less if alcohol is also ingested.
The symptoms of barbiturate withdrawal can be severe and may cause death. Minor withdrawal symptoms may appear 8 to 12 hours after the last dose of a barbiturate.
These symptoms usually appear in the following order: anxiety, muscle twitching, tremor of hands and fingers, progressive weakness, dizziness, distortion in visual perception, nausea, vomiting, insomnia, and orthostatic hypotension. Major withdrawal symptoms (convulsions and delirium) may occur within 16 hours and last up to 5 days after abrupt cessation of these drugs. Intensity of withdrawal symptoms gradually declines over a period of approximately 15 days. Individuals susceptible to barbiturate abuse and dependence include alcoholics and opiate abusers, as well as other sedative-hypnotic and amphetamine abusers.
Drug dependence to barbiturates arises from repeated administration of a barbiturate or agent with barbiturate-like effect on a continuous basis, generally in amounts exceeding therapeutic dose levels. The characteristics of drug dependence to barbiturates include: (a) a strong desire or need to continue taking the drug; (b) a tendency to increase the dose; (c) a psychic dependence on the effects of the drug related to subjective and individual appreciation of those effects; and (d) a physical dependence on the effects of the drug requiring its presence for maintenance of homeostasis and resulting in a definite, characteristic, and self-limited abstinence syndrome when the drug is withdrawn.
Treatment of barbiturate dependence consists of cautious and gradual withdrawal of the drug. Barbiturate-dependent patients can be withdrawn by using a number of different withdrawal regimens. In all cases withdrawal takes an extended period of time. One method involves substituting a 30 mg dose of phenobarbital for each 100 to 200 mg dose of barbiturate that the patient has been taking. The total daily amount of phenobarbital is then administered in 3 to 4 divided doses, not to exceed 600 mg daily. Should signs of withdrawal occur on the first day of treatment, a loading dose of 100 to 200 mg of phenobarbital may be administered IM in addition to the oral dose. After stabilization on phenobarbital, the total daily dose is decreased by 30 mg a day as long as withdrawal is proceeding smoothly. A modification of this regimen involves initiating treatment at the patient's regular dosage level and decreasing the daily dosage by 10 percent if tolerated by the patient.
Infants physically dependent on barbiturates may be given phenobarbital 3 to 10 mg/kg/day. After withdrawal symptoms (hyperactivity, disturbed sleep, tremors, hyperreflexia) are relieved, the dosage of phenobarbital should be gradually decreased and completely withdrawn over a 2-week period.
Read the entire FDA prescribing information for Nembutal (Pentobarbital)