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Amobarbital is an intermediate-acting barbiturate with hypnotic properties used in short-term treatment of insomnia and to reduce anxiety and provide sedation preoperatively.(1,2)
Amobarbital is administered by intravenous infusion or intramuscular injection. The duration of its hypnotic effect is about 6 to 8 hours. The drug distributes throughout the body, with a volume of distribution of 0.9 to 1.4 L/kg, and about 59% of a dose is bound to plasma proteins. Metabolism takes place in the liver primarily via hepatic microsomal enzymes. Its half-life is about 15 to 40 hours (mean: 25 hours). Excretion occurs mainly in the urine.(2,3)
Monitoring amobarbital therapy
The therapeutic range of amobarbital is 1 to 5 mcg/mL, with toxicity typically associated with concentrations >10 mcg/mL.(2)
The concentration at which toxicity occurs varies; results should be interpreted in light of the clinical situation.
Therapeutic concentration: 1.0-5.0 mcg/mL
Toxic concentration: >10.0 mcg/mL
Concentration at which toxicity occurs varies and should be interpreted in light of clinical situation.
1. Goodman and Gilman's: The Pharmacological Basis of Therapeutics. 10th edition. New York, McGraw-Hill Book Company, 2001
2. Teitz Textbook of Clinical Chemistry and Molecular Diagnostics. Fourth edition. St. Louis, MO, Elsevier Saunders, 2006, pp 1091
3. Disposition of Toxic Drugs and Chemicals in Man. Seventh edition. Edited by RC Baselt. Foster City, CA, Biomedical Publications, 2004, pp 1254