The aim of this study was to characterize pharmacokinetics of fentanyl during and after Living Donor Liver Transplantation (LDLT), using population pharmacokinetic analysis with non linear mixed effects modeling.

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.

Inclusion Criteria:

• Patients between 19 - 65 years of age
• Over 45kg of weight
• Written Informed consent
• Patients receiving a liver graft from living donor (ASA PS III or IV)

Exclusion Criteria:

• Patients with renal dysfunction
• Patients with Fulminant hepatic failure
• Patients participated other clinical trials within 2 months
• Unable or Unwilling to give informed consent
• Abnormal test results with clinical significance