title: In vitro remifentanil metabolism: the effects of whole blood constituents and plasma butyrylcholinesterase.
abstract: We designed this in vitro study to determine whether the half-life of remifentanil was altered in butyrylcholinesterase-deficient patients. Test tubes containing Krebs buffered solution, whole blood, plasma, or red cells from both normal and butyrylcholinesterase-deficient patients were incubated with remifentanil. Remifentanil concentrations were determined by using gas chromatography and mean half-lives were calculated by using a nonlinear regression analysis. There were no differences in whole blood, red cells, or plasma half-life between normal and butyrylcholinesterase-deficient volunteers. In both normal and butyrylcholinesterase-deficient volunteers, whole blood and plasma had a significantly longer half-life than the red cell component. Extrapolation to the in vivo setting would suggest that a butyrylcholinesterase-deficient patient should not have altered remifentanil kinetics.
  
  
  CONCLUSIONS
  This was a test-tube-designed study to determine whether an enzyme deficiency (butyrylcholinesterase deficiency) changes the way remifentanil is metabolized. It seems that remifentanil dosage does not need to be changed in patients with butyrylcholinesterase deficiency.
authors.affiliation: Department of Anesthesiology, School of Medicine, University of Pittsburgh, 3705 5th Avenue, Pittsburgh, PA 15213-2583, USA. davispj@anes.upmc.edu
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Davis
authors.forename: Richard L
authors.initials: RL
authors.lastname: Stiller
authors.forename: Annette S
authors.initials: AS
authors.lastname: Wilson
authors.forename: Francis X
authors.initials: FX
authors.lastname: McGowan
authors.forename: Talmage D
authors.initials: TD
authors.lastname: Egan
authors.forename: Keith T
authors.initials: KT
authors.lastname: Muir
mesh_terms: D000328:Adult; D018686:Anesthetics, Intravenous / Q000097:blood / Q000378:metabolism*; D002091:Butyrylcholinesterase / Q000097:blood / Q000172:deficiency / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism; D006207:Half-Life; D006801:Humans; D017711:Nonlinear Dynamics; D010880:Piperidines / Q000097:blood / Q000378:metabolism*; D010949:Plasma / Q000378:metabolism; D000077208:Remifentanil
chemical_list: D018686:Anesthetics, Intravenous; D010880:Piperidines; D002091:Butyrylcholinesterase; D000077208:Remifentanil