Impact of CYP3A4*1G Polymorphism on Metabolism of Fentanyl in Chinese Patients Undergoing Lower Abdominal Surgery

• CYP3A4*1G polymorphism [ Time Frame: 3 month ] [ Designated as safety issue: Yes ]
  According to CYP3A4*1G polymorphism,patients are devided into three groups: *1/*1,*1/*1G,*1G/*1G
• Plasma concentration of fentanyl [ Time Frame: 4 month ] [ Designated as safety issue: Yes ]
  Plasma concentration of fentanyl may related to the metabolism of fentanyl

• The visual analog scale 24 hours postoperative [ Time Frame: 1 year ] [ Designated as safety issue: Yes ]
  The visual analog scale (VAS) is used for pain evaluation at rest during patient-controlled analgesia (PCA) treatment 0 h, 12 h and 24 h after operation
• PCA fentanyl consumption [ Time Frame: 1 year ] [ Designated as safety issue: Yes ]
  PCA fentanyl consumption and adverse effects are recorded during the first 24 h after surgery.
• The correlation between plasma fentanyl concentration and PCA fentanyl consumption [ Time Frame: 1 year ] [ Designated as safety issue: Yes ]

Purpose: This study aimed to investigate the impact of CYP3A4*1G genetic polymorphism on metabolism of fentanyl in Chinese patients undergoing lower abdominal surgery. Methods: 176 patients receiving elective lower abdominal surgery under general anesthesia were recruited into this study. Genotyping of CYP3A4*1G was carried out by direct sequencing. The plasma fentanyl concentration was detected 30 min after anesthesia induction by high performance liquid chromatography-ultraviolet ray (HPLC-UV). The visual analog scale (VAS) was used for pain evaluation at rest during patient-controlled analgesia (PCA) treatment 0 h, 12 h and 24 h after operation. PCA fentanyl consumption and adverse effects were recorded during the first 24 h after surgery.

176 Chinese patients receiving elective lower abdominal surgery under general anesthesia

• Pain
• Surgery

• *1/*1
  Grouped by CYP3A4*1G polymorphism, wild-type homozygote
• *1/*1G
  Grouped by CYP3A4*1G polymorphism,*1/*1G: mutant heterozygote
• *1G/*1G
  Grouped by CYP3A4*1G polymorphism,*1G/*1G: mutant homozygote

Inclusion Criteria:

• Aged 20-65 years
• Anesthesiologists (ASA) physical status I or II;
• With ±20% of ideal body weight;
• Received PCA administration;
• Agreed to participate the research

Exclusion Criteria:

• History of chronic pain;
• Psychiatric diseases;
• Diabetes mellitus;
• Severe cardiovascular diseases;
• Kidney or liver diseases;
• Alcohol or drug abuse (according to the criteria of DSM-IV);
• Pregnancy or at lactation period;
• Consumed drugs (1week) or foods (3 days) known to inhibit or induce the expression of CYP3A4 enzymes prior to surgery;
• Refused PCA administration;
• Disagree to participate to the research