title: Population pharmacokinetics and pharmacodynamics of brief etomidate infusion in healthy volunteers.
abstract: This study established the pharmacokinetic and pharmacodynamic relationships of the bispectral index (BIS) and Observer's Assessment of Alertness/Sedation (OAA/S) scale with effect site drug concentrations during and after brief etomidate infusion. Eighteen American Society of Anesthesiologists status I or II volunteers received etomidate (0.2%) infusion at 5 mg/min until the loss of eyelash reflexes, and spontaneous recovery was allowed. Data for plasma etomidate concentrations, BIS, and OAA/S were collected every minute and analyzed by NONMEM. A 2-compartment pharmacokinetic model and a pharmacodynamic sigmoid E(max) model fit the data best, with volumes of distribution at central and peripheral compartments of 4.45 and 74.90 L, respectively, and systemic and intercompartmental clearances of 0.63 and 3.16 L/min, respectively. t(1/2)k(e0) was 1.550 min. EC(50) values were 0.526 and 0.554 µg/mL, and gamma values were 2.25 and 6.24 for BIS and OAA/S, respectively. The prediction probability between OAA/S and BIS was 0.8. The slopes of the curves suggest that BIS is a better monitor of depth of sedation and hypnosis, whereas OAA/S may be more useful for monitoring sleep versus wakefulness. These results should be interpreted within the context of short-term etomidate infusion of less than 10 minutes.
authors.affiliation: Department of Anesthesia, The University of Iowa Hospitals and Clinics, Roy J. and Lucille A. Carver College of Medicine, 200 Hawkins Drive #6505-3 JCP, Iowa City, IA 52242, USA.
authors.forename: Kotaro
authors.initials: K
authors.lastname: Kaneda
authors.forename: Susumu
authors.initials: S
authors.lastname: Yamashita
authors.forename: Sukyung
authors.initials: S
authors.lastname: Woo
authors.forename: Tae-Hyung
authors.initials: TH
authors.lastname: Han
mesh_terms: D000328:Adult; D018686:Anesthetics, Intravenous / Q000009:adverse effects / Q000493:pharmacokinetics* / Q000494:pharmacology*; D056805:Consciousness Monitors; D054810:Deep Sedation / Q000379:methods; D005045:Etomidate / Q000009:adverse effects / Q000493:pharmacokinetics* / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D008954:Models, Biological; D016343:Monitoring, Intraoperative / Q000379:methods; D009207:Myoclonus / Q000139:chemically induced; D012890:Sleep / Q000187:drug effects; D014851:Wakefulness / Q000187:drug effects
chemical_list: D018686:Anesthetics, Intravenous; D005045:Etomidate