Short-term treatment of insomnia (i.e., ≤2 weeks duration); decreased effectiveness for sleep induction and maintenance after 2 weeks.
Has been used for routine sedation. However, barbiturates used infrequently for this indication since there are few clinical situations in which oral barbiturates provide a safety or efficacy advantage over nonbarbiturate sedatives/hypnotics.
Surgery and Preanesthesia
Preoperatively, to produce sedation and relieve anxiety.
Provide basal hypnosis for general, spinal, or regional anesthesia, or to facilitate intubation procedures.
IV diazepam generally considered drug of choice for termination of status epilepticus.
Drug Withdrawal
Withdrawal of barbiturate or nonbarbiturate hypnotics in physically dependent patients.
Agitated Behavior
Has been used to control acute episodes of agitated behavior in psychoses†; however, little value in long-term management of psychoses.
Coma Induction
Has been used in high doses to induce coma in the management of cerebral ischemia† and increased intracranial pressure† associated with head trauma, stroke, Reye’s syndrome, cardiac arrest, asphyxiation, or drowning.
Has been used to ameliorate or prevent sequelae associated with cerebral ischemia during neurosurgical procedures† that require long periods of cerebral hypoxia.
Dosage and Administration
General
Adjust dosage carefully and slowly according to individual requirements and response.
Following chronic administration, withdraw pentobarbital slowly to avoid the possibility of precipitating withdrawal symptoms if the patient is physically dependent on the drug.
To prevent rebound in rapid eye movement (REM) sleep, withdrawal of a single therapeutic dose over 5 or 6 days (e.g., reducing dosage from 3 to 2 doses daily for 1 week) has been recommended when barbiturates are discontinued following prolonged use.
Insomnia
Do not administer for periods >2 weeks.
Administration
Administer by IM or slow IV injection.
IV Administration
For solution and drug compatibility information, see Compatibility under Stability.
Reserve IV administration for inducing anesthesia or emergency treatment of acute seizure episodes or acute episodes of agitated behavior in psychoses. (See Seizure Disordersand also Agitated Behavior under Uses.)
Usually administered in a concentration of 50 mg/mL.
Must be administered by slow IV injection and in fractional doses to allow for adequate time for pentobarbital to distribute into CNS. A time interval of ≥1 minute is required to determine the full effect of an IV dose.
Administer under close supervision and in a setting where vital signs can be monitored; BP, respiration, and cardiac function maintained; and equipment for resuscitation and artificial ventilation are readily available. (See Respiratory and Cardiovascular Effects under Cautions.)
Avoid intra-arterial and extravascular injection. (See Intra-arterial Injection under Cautions.)
Rate of Administration
Do not exceed 50 mg/minute. (See Respiratory and Cardiovascular Effects under Cautions.)
IM Administration
Administer by deep IM injection into a large muscle.
Administer a maximum volume of 5 mL at any one site to avoid tissue irritation.
After administration of large hypnotic doses, observe patient closely for 20–30 minutes and monitor vital signs to ensure narcosis will not be excessive.
IV dosage generally determined by patient’s reaction to slow administration of the drug.
A time interval of >1 minute required to determine the full effect of an IV dose.
Pediatric Patients
Insomnia
IM
2–6 mg/kg or 125 mg/m2 as a single dose (maximum 100 mg).
Surgery and Preanesthesia
IM
Usually, approximately 5 mg/kg.
IV
Initially, usually 50 mg. If necessary, administer subsequent doses after >1 minute.
Seizure Disorders
IV
Initially, usually 50 mg. If necessary, administer subsequent doses after >1 minute.
Agitated Behavior
IV
Initially, usually 50 mg. If necessary, administer subsequent doses after >1 minute.†
Adults
Insomnia
IM
150–200 mg as a single dose.
IV
Initially, usually 100 mg for an adult weighing 70 kg. After >1 minute, if necessary, administer additional small doses up to a total of 200–500 mg.
Surgery and Preanesthesia
IM
150–200 mg as a single dose.
Seizures
IV
Initially, usually 100 mg. After >1 minute, if necessary, administer additional small doses up to a total of 200–500 mg.
Administer minimum dosage to avoid compounding the CNS and respiratory depression which may follow seizures. (See CNS Depression and also Respiratory and Cardiovascular Effects, under Cautions.)
Drug Withdrawal
IM
Establish a stabilizing dose (generally adminstered at 6-hour intervals), then decrease the daily dose by no more than 100 mg per day. Severely dependent patients can usually be withdrawn from barbiturates in 14–21 days.
Agitated Behavior
IV
Initially, usually 100 mg. After >1 minute, if necessary, administer additional small doses up to a total of 200–500 mg.†
Potential for paradoxical excitement and/or euphoria, restlessness, or delirium in patients with severe pain. Barbiturates could mask important symptoms in patients with acute or chronic pain. Use with caution in such patients. Should not be used in the presence of uncontrolled pain.
Abuse Potential
Possible tolerance, psychological dependence, and physical dependence following prolonged administration.
Withdrawal Effects
Abrupt cessation after prolonged use in dependent individuals may result in withdrawal symptoms (e.g., delirium, convulsions) and potentially be fatal. Drug must be withdrawn gradually in patients receiving excessive dosages over extended periods of time.
CNS Depression
Performance of activities requiring mental alertness or physical coordination may be impaired.
Concurrent use of other CNS depressants may potentiate CNS depression. (See Specific Drugs under Interactions.)
Respiratory and Cardiovascular Effects
Possible respiratory depression, apnea, laryngospasm, or vasodilation and hypotension, particularly if pentobarbital is administered IV too rapidly. Administer slowly; personnel and equipment should be readily available for administration of artificial respiration.
Fetal/Neonatal Morbidity
May cause fetal harm. If used during pregnancy or if patient becomes pregnant, apprise of potential fetal hazard.
Retrospective, case-controlled studies indicate an association between maternal ingestion of barbiturates and a higher than expected incidence of fetal abnormalities.
Barbiturates have caused postpartum hemorrhage and hemorrhagic disease in neonates; readily reversible with vitamin K therapy.
Possible withdrawal symptoms in neonates born to women who received barbiturates throughout the last trimester of pregnancy. Premature neonates are particularly susceptible to the depressant effects of barbiturates.
Porphyria
Potential exacerbation of acute intermittent porphyria or porphyria variegata. (See Contraindications under Cautions.)
Complex Sleep-related Behaviors
Potential risk of complex sleep-related behaviors such as sleep-driving (i.e., driving while not fully awake after ingesting a sedative-hypnotic drug, with no memory of the event), making phone calls, or preparing and eating food, while asleep.
Sensitivity Reactions
Potential risk of anaphylaxis and angioedema; may occur as early as with the first dose of drug.
Dermatologic Effects and Hypersensitivity Reactions
Exfoliative dermatitis (e.g., Stevens-Johnson syndrome), sometimes fatal, reported rarely. Because skin eruptions can precede potentially fatal reactions, discontinue pentobarbital whenever dermatologic reactions occur.
General Precautions
Intra-arterial Injection
Inadvertent intra-arterial administration can cause local reactions varying in severity from transient pain to gangrene. Inadvertent extravascular injection may cause local tissue damage and result in necrosis.
Discontinue injection if the patient complains of pain in limb.
Suicide
Use with caution, if at all, in patients with depression or suicidal tendencies.
Possible enhanced metabolism of estrogenic and progestinic components; potential for decreased oral contraceptive effectiveness and increased risk of pregnancy with pentobarbital pretreatment or concurrent therapy
Dosage adjustment of corticosteroid may be required; closely monitor patients (especially asthmatics) receiving corticosteroids when pentobarbital is initiated
Possible increased plasma pentobarbital concentrations
Monitor plasma pentobarbital concentrations and adjust dosage as needed
Pharmacokinetics
Absorption
Onset
Following IV administration, onset occurs within 1 minute.
Following IM administration, onset occurs within 10–25 minutes.
Duration
Variable; patient-dependent and may vary occasionally within same patient. About 15 minutes following IV administration.
Plasma Concentrations
Plasma concentrations of 1–5 mcg/mL generally produce sedation and plasma concentrations of 5–15 mcg/mL generally produce sleep; however, plasma concentrations >10 mcg/mL may produce deep coma and those >30 mcg/mL are potentially lethal.
Distribution
Extent
Rapidly distributed to all tissues and fluids, with high concentrations in the brain, liver, and kidneys.
Crosses the placenta and is distributed into milk.
Plasma Protein Binding
Approximately 35–45%.
Elimination
Metabolism
Metabolized primarily by hepatic microsomal enzymes.
Elimination Route
Excreted principally in urine, mostly as metabolites; excreted less commonly in the feces.
Half-life
Biphasic; terminal half-life is 35–50 hours.
Stability
Storage
Parenteral
Solution for Injection
30°C (brief exposure up to 40°C permitted). Protect from freezing and avoid excessive heat.
Do not use if discoloration or precipitation occurs.
Compatibility
For information on systemic interactions resulting from concomitant use, see Interactions.
CNS effects appear to be related, at least partially, to the drug's ability to enhance activity of GABA, the principal inhibitory neurotransmitter in the CNS, by altering inhibitory synaptic transmissions that are mediated by GABAA receptors.
Capable of producing all levels of CNS depression—from mild sedation to hypnosis to deep coma to death.
Anticonvulsant effects of barbiturates are multiple and rather nonselective. Principal mechanism of action appears to be reduction of monosynaptic and polysynaptic transmission resulting in decreased excitability of the entire nerve cell; barbiturates also increase the threshold for electrical stimulation of the motor cortex.
Barbiturates lower serum bilirubin concentrations in neonates and patients with congenital nonhemolytic unconjugated hyperbilirubinemia, presumably by induction of glucuronyl transferase, the enzyme that conjugates bilirubin.
Advice to Patients
Potential for pentobarbital to impair mental alertness or physical coordination; do not drive or operate machinery until effects on individual are known.
Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs and alcohol consumption. Importance of avoiding alcohol while taking the drug.
Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed.
Importance of informing patients of other important precautionary information. (See Cautions.)
Preparations
Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.
Subject to control under the Federal Controlled Substances Act of 1970 as schedule II (C-II) drugs.
† Use is not currently included in the labeling approved by the US Food and Drug Administration.
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.
Sign up with Facebook
