Monitoring of pentobarbital therapy treatment
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Pentobarbital is a short-acting barbiturate with anticonvulsant and sedative-hypnotic properties. Uses include sedation induction; relief of preoperative anxiety; control of status epilepticus or seizures resulting from meningitis, tetanus, alcohol withdrawal, poisons, chorea, or eclampsia; and induction of coma in the management of cerebral ischemia and increased intracranial pressure that may follow stroke or head trauma.(1,2)
Pentobarbital is administered orally, parenterally, and rectally. The duration of hypnotic effect is about 1 to 4 hours. The drug distributes throughout the body, with about 35% to 45% of a dose bound to plasma proteins in the blood. Metabolism takes place in the liver via oxidation to the inactive metabolite hydroxypentobarbital. Elimination is biphasic; half-life is about 4 hours in the first phase, and 35 to 50 hours in the second phase. Excretion occurs through the urine, mainly as glucuronide conjugates of metabolites, with only about 1% excreted as unchanged drug.(1,2) Tolerance to pentobarbital's hypnotic effects occurs after about 2 weeks of continuous dosing.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
Hypnotic: 1-5 mcg/mL
Therapeutic coma: 20-50 mcg/mL
Reducing intracranial pressure: 30-40 mcg/mL
This degree of sedation requires artificial respiratory support.
Toxic concentration: >10 mcg/mL
The concentration at which toxicity occurs varies; results should be interpreted in light of clinical situation.
Hypnotic: 1 to 5 mcg/mL
Therapeutic coma: 20 to 50 mcg/mL
Reducing intracranial pressure: 30 to 40 mcg/mL
-This degree of sedation requires artificial respiratory support.
Toxic: >10 mcg/mL
-The concentration at which toxicity occurs varies; results should be interpreted in light of clinical situation.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Package insert: NEMBUTAL Sodium Solution (pentobarbital sodium injection). Deerfield, IL: Ovation Pharmaceuticals Inc., October, 2007
2. Physician's Desk Reference (PDR). 61st edition. Montvale, NJ: Thomson PDR, 2007
3. Teitz Textbook of Clinical Chemistry and Molecular Diagnostics. Fourth edition. St. Louis, MO. Elsevier Saunders, 2006 pp 2312