Population Pharmacokinetics of Fentanyl in Patients Undergoing Living Donor Liver Transplantation

Patients received an initial intravenous bolus of fentanyl 100 μg and infused at variable rates ranging from 250 to 400 μg/hr.

Arterial blood samples (3ml) were taken immediately before the start of infusion (baseline), and at scheduled time which were coincident with laboratory tests during surgery as follows. In pre-anhepatic phase, blood were taken at 10min, 30min, 1hr, 3hr, 5hr until clamping of the hepatic blood supply and venous drainage, after the star of anhepatic phase, blood were taken at 5 min, 10 min, 30 min, 60 min, 90 min, 2hr until the vessels were reconnected to new liver. In neo-hepatic phase, blood were taken at 5min, 10min, 30min, 60min, 90min, 2hr, 3hr, 5hr until fentanyl-infusion stop, and at 0hr, 1hr, 3hr, 5hr, 8hr, 12hr, 24hr immediately after the stop of infusion. Samples were collected into tubes containing heparin as an anticoagulant and immediately placed on ice. After centrifugation for 8 min at 1800 g, the plasma was transferred to a cryovial and stored at -70°C until assay.