Effect of PXR* 1B polymorphism on postoperative analgesia with fentanyl in patients undergoing gynecological operation / 中华麻醉学杂志

ABSTRACT

Objective To investigate the effect of PXR* 1B polymorphism on postoperative analgesia with fentanyl in the patients undergoing gynecological operation.Methods A total of 102 female patients from Henan province, of Han nationality, aged 20-50 yr, of American Society of Anesthesiologists physical status Ⅰ or Ⅱ , with body mass index of 14.8-30.0 kg/m2, scheduled for elective abdominal total hysterectomy or myomectomy under general anesthesia, were enrolled in this study.PXR genetic polymorphic sites were analyzed by polymerase chain reaction (PCR)-direct DNA sequencing.PXR* 1B haplotype was analyzed by the PHASE V.2.1 software.The patients were assigned into 3 groups according to their genotypes PXR* 1B haplotype group (group PXR* 1B), non-PXR* 1B haplotype group (group n-PXR* 1B) and PXR* 1B/PXR * 1B group (group PXR* 1B/PXR* 1B).Postoperative pain was assessed with visual analogue scale (VAS) score.When VAS ＞ 3, fentanyl 20 μg was injected intermittently until VAS ≤ 3, and then a pump was connected to perform patient-controlled intravenous analgesia (PCIA) with fentanyl.PCIA solution contained fentanyl 1.0 mg and droperidol 5 mg in 100 ml of normal saline.The PCA pump was set up with a 2 ml bolus dose, a 5 min lockout interval and background infusion at a rate of 0.5 ml/h.The number of successfully delivered doses was set at 7 times, and the maximal amount of fentanyl was 145 μg.If exceeding the maximal dose, the VAS score was still more than 3, nonsteroidal anti-inflammatory drugs were given as rescue medication.VAS score immediately after the end of operation, and the consumption of fentanyl within 24 h after operation were recorded.Midazolam 0.1 mg/kg was injected intravenously during induction of general anesthesia, and 1 h later venous blood samples were collected for determination of plasma 1'-hydroxymidazolam and midazolam concentrations.The ratio of 1'-hydroxymidazolam concentration to midazolam concentration was calculated to reflect the activity of CYP3A4.Results No patients required rescue anesthetics in the three groups.There were 27 cases in group PXR * 1B, 53 cases in group n-PXR* 1B, and 22 cases in group PXR* 1B/PXR* 1B.PXR* 1B allele frequency was 37.2％.There was no significant difference in VAS score immediately after the end of operation, consumption of fentanyl within 24 h after operation, and activity of CYP3A4 between the three groups (P＞0.05).Conclusion PXR* 1B polymorphism has no effect on postoperative analgesia with fentanyl in the patients undergoing gynecological operation, and is not one of the genetic factors producing individual variation in postoperative analgesia.