title: Vecuronium kinetics and dynamics in anesthetized infants and children.
abstract: Vecuronium kinetics and dynamics were determined in five infants (3 to 11 months old) and five children (1 to 5 years old) during anesthesia with 70% nitrous oxide and 0.9 MAC halothane. Vecuronium was infused intravenously at a rate of 2.5 micrograms/kg/min while twitch tension of the adductor pollicis muscle was recorded and venous blood samples were drawn for determination of vecuronium concentrations by mass spectrometry. The elimination t1/2 was determined by linear regression of the log postdistribution concentration-time data; these values and noncompartmental techniques were used to calculate total plasma clearance (Cl), volume of distribution at steady state (Vdss), and mean residence time. The steady-state plasma concentration resulting in 50% depression of twitch tension (Cpss50) was determined by an effect compartment and a sigmoid concentration vs. paralysis model. Vdss was larger in infants (357 +/- 70 ml/kg; mean +/- SD) than in children (204 +/- 116 ml/kg), and Cl was of the same order for infants and children (5.6 +/- 1.0 and 5.9 +/- 2.4 ml/kg/min). Mean residence time was longer in infants (66.3 +/- 22.9 minutes) than in children (34.3 +/- 8.0 minutes). Cpss50 was lower in infants (57 +/- 18 ng/ml) than in children (110 +/- 28 ng/ml). The quantity of vecuronium in the body at steady state at 50% depression of twitch tension (Vdss X Cpss50) was similar in infants and children (21.2 +/- 9.9 and 19.0 +/- 3.3 micrograms/kg). During comparable nitrous oxide-halothane anesthesia, age-related changes in Vdss, Cl, and Cpss50 were much like those found for d-tubocurarine.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.forename: D M
authors.initials: DM
authors.lastname: Fisher
authors.forename: K
authors.initials: K
authors.lastname: Castagnoli
authors.forename: R D
authors.initials: RD
authors.lastname: Miller
mesh_terms: D000375:Aging; D000758:Anesthesia; D002675:Child, Preschool; D005260:Female; D006221:Halothane; D006801:Humans; D007223:Infant; D007263:Infusions, Parenteral; D007700:Kinetics; D008297:Male; D009469:Neuromuscular Junction / Q000187:drug effects; D009609:Nitrous Oxide; D010197:Pancuronium / Q000031:analogs & derivatives* / Q000097:blood / Q000378:metabolism; D014673:Vecuronium Bromide
chemical_list: D014673:Vecuronium Bromide; D010197:Pancuronium; D009609:Nitrous Oxide; D006221:Halothane