Pentobarbital Sodium

Pronunciation: pen-toe-BAR-bih-tahl SO-dee-uhm
Class: Barbiturate, short-acting, Sedative and hypnotic

Trade Names

Nembutal Sodium
- Injection 50 mg/mL

Pharmacology

Depresses sensory cortex, decreases motor activity, alters cerebellar function, and produces drowsiness, sedation and hypnosis.

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Pharmacokinetics

Absorption

Absorbed in varying degrees. T max is 15 min (IV), maximal CNS depression.

Distribution

Rapidly distributed to all tissues and fluids with high concentration in brain, liver, and kidneys due to lipid solubility. Protein binding is 60% to 70%. Distributes into breast milk.

Metabolism

Metabolized by hepatic microsomal enzyme system.

Elimination

Urine (very little unchanged); in the feces is less common. The t ½ is 15 to 50 h.

Onset

Immediate following IV administration.

Duration

3 to 4 h.

Indications and Usage

Sedation; short-term treatment of insomnia; preanesthesia; emergency control of convulsions.

Contraindications

Hypersensitivity to barbiturates; manifest or latent porphyria.

Dosage and Administration

Insomnia
Adults

IV 100 mg (max IV rate, 50 mg/min). IM 120 to 200 mg (max IM dose, 500 mg or 5 mL volume regardless of concentration).

Sedation
Children

IM 2 to 6 mg/kg (max, 100 mg). IV 50 mg.

Convulsions
Adults

IV Use minimum dose to avoid compounding depression. Administer slowly to allow time for drug to penetrate the blood-brain barrier. Do not exceed 50 mg/min.

General Advice

  • Give IM injections deeply into large muscle. Do not exceed max IM dose of 500 mg or 5 mL of volume (regardless of concentration).
  • For IV administration, inject into large vein; do not exceed max IV rate of 50 mg/min, do not administer into artery and do not allow perivascular extravasation.

Storage/Stability

  • Store at room temperature. Do not use if discolored or if precipitate forms.

Drug Interactions

Alcohol, CNS depressants

May produce additive depressant effects.

Anticoagulants, beta-blockers, calcium channel blockers (eg, nifedipine, verapamil), theophylline

Activity of these drugs may be reduced.

Anticonvulsants

Serum concentrations of carbamazepine, valproic acid and succinimides may be reduced. Valproic acid may increase barbiturate serum levels.

Corticosteroids

Effectiveness may be reduced.

Estrogen, estrogen-containing oral contraceptives

May cause decreased contraceptive and estrogen effect.

Griseofulvin

Decreased griseofulvin levels.

Laboratory Test Interactions

Decreased serum bilirubin concentrations, false-positive phentolamine test, decreased response to metyrapone and impaired absorption of radioactive cyanocobalamin.

Adverse Reactions

Cardiovascular

Bradycardia; hypotension; syncope.

CNS

Drowsiness; agitation; confusion; headache; hyperkinesia; ataxia; CNS depression; paradoxical excitement; nightmares; psychiatric disturbances; hallucinations; insomnia; dizziness.

GI

Nausea; vomiting; constipation.

Hepatic

Liver damage.

Hematologic

Blood dyscrasias (eg, agranulocytosis, thrombocytopenia).

Respiratory

Hypoventilation; apnea; laryngospasm; bronchospasm.

Miscellaneous

Hypersensitivity reactions (eg, angioedema, rashes, exfoliative dermatitis); fever; injection-site reactions (eg, local pain, thrombophlebitis).

Precautions

Pregnancy

Category D .

Lactation

Excreted in breast milk.

Children

May respond with excitement rather than depression.

Elderly

More sensitive to drug effects; dosage reduction is required.

Renal Function

Use drug with caution; dosage reduction may be required.

Hepatic Function

Use drug with caution; dosage reduction may be required.

Dependence

Tolerance or psychological and physical dependence may occur with continued use.

IV administration

Do not exceed max IV rate; respiratory depression, apnea and hypotension may result. Parenteral solutions are highly alkaline; extravasation may cause tissue damage and necrosis. Inadvertent intra-arterial injection may lead to arterial spasm, thrombosis, and gangrene.

Seizure disorders

Status epilepticus may result from abrupt discontinuation.

Overdosage

Symptoms

CNS and respiratory depression, Cheyne-Stokes respiration, areflexia, constriction of pupils, oliguria, tachycardia, hypotension, lowered body temperature, coma, apnea, circulatory collapse, respiratory arrest, death.

Patient Information

  • Warn patient that medication may be habit forming and for this reason it is important to take medicine as directed. Taking too little or too much can have serious complications.
  • Instruct patient to report the following symptoms to health care provider: nausea, vomiting, drowsiness, dizziness, fever, sore throat, mouth sores, easy bleeding, bruising, skin irritation, or exaggerated sunburn.
  • Caution patient to avoid intake of alcoholic beverages or other CNS depressants.
  • Advise patient that drug may cause drowsiness, and to use caution while driving or performing other tasks requiring mental alertness.

Copyright © 2009 Wolters Kluwer Health.

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