Amobarbital Sodium

Trade Names:Amytal Sodium- Powder for injection 500 mg

Pharmacology

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

Pharmacokinetics

Distribution

Rapidly distributed to all tissues and fluids, with high concentrations in brain, liver, and kidneys. Bound to plasma and tissue proteins.

Metabolism

Metabolized by hepatic microsomal enzyme system.

Elimination

Plasma t _½ is about 25 h. Metabolites excreted in urine and to a lesser extent in the feces. Negligible amount eliminated unchanged in urine.

Onset

0.75 to 1 h.

Duration

6 to 8 h.

Indications and Usage

Relief of anxiety; short-term therapy for insomnia; induction of preanesthetic sedation.

Contraindications

Hypersensitivity to barbiturates; history of addiction to sedative-hypnotic drugs; history of porphyria; severe liver impairment; respiratory disease with dyspnea; patients with nephritis.

Dosage and Administration

PO/IM/IV 65 to 200 mg at bedtime.

PO/IM/IV 30 to 50 mg twice daily or 3 times daily.

PO/IM 2 to 6 mg/kg/dose.

General Advice

• Reconstitute solution with sterile water for injection, rotating vial to mix. Do not shake vial. Solution should clear within 5 min.
• Do not dilute with lactated Ringer's solution.
• Do not administer if solution is discolored or if precipitate is present.
• After reconstitution, inject solution within 30 min.

Storage/Stability

Store at room temperature. Do not freeze.

Drug Interactions

Depressant effects of these drugs may be enhanced.

Activity of these drugs may be reduced.

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

Effectiveness may be reduced.

Effectiveness may be reduced.

Laboratory Test Interactions

Decreased serum bilirubin; false-positive phentolamine test results.

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.

Hematologic

Blood dyscrasias (agranulocytosis, thrombocytopenia).

Hepatic

Liver damage.

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

Safety and efficacy not established in children younger than 6 yr of age.

Elderly

Reduce dosage.

Renal Function

Use with caution; reduce dosage.

Hepatic Function

Use with caution; reduce dosage.

Drug dependence

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

Overdosage

Symptoms

Respiratory depression, CNS depression progressing to Cheyne-Stokes respiration, oliguria, tachycardia, hypotension, hypothermia, coma, shock, cessation of electrical activity in brain (extreme overdose).

Patient Information

• Advise patient not to increase dosage or stop therapy without advice of health care provider.
• Instruct patient to avoid alcohol, nicotine, and caffeine products.
• Advise patient that drug may cause drowsiness, and to use caution while driving or performing other tasks requiring mental alertness.
• Inform patient to report the following symptoms to health care provider: excessive sleepiness, fatigue, nausea, vomiting.

Copyright © 2009 Wolters Kluwer Health.