Effect of IL-1RN genetic polymorphism on potency of fentanyl for postoperative intravenous analgesia

Abstract

Objective To investigate the effect of IL-1RN genetic polymorphism on the potency of fentanyl for postoperative intravenous analgesia. Methods Two hundred and seventy patients of Han nationality(native of Henan province), aged 20-50 yr, of American Society of Anesthesiologists physical status Ⅰ or Ⅱ, undergoing elective abdominal total hysterectomy or myomectomy under general anesthesia, were enrolled in this study.Blood samples were taken from the peripheral vein for DNA extraction using phenol chloroform extracting method, and polymerase chain reaction and agarose gel electrophoresis were used for IL-1RN genotying.The patients were assigned to one of 5 groups according to their genotypes: IL-1RN I/I wild homozygote group(group Ⅰ/Ⅰ), IL-1RN I/II mutation heterozygote group(group Ⅰ/Ⅱ), IL-1RN II/II mutation homozygote group(group Ⅱ/Ⅱ), IL-1RN I/III mutation heterozygote group(group Ⅰ/Ⅲ), and IL-1RN I/IV mutation heterozygote group(group Ⅰ/Ⅳ). Pain was assessed using visual analogue scale(VAS)score after the patients recovered from anesthesia.When VAS score>3, the patients were given fentanyl 20 μg every 5 min until VAS score decreased to ≤3.Patient-controlled intravenous analgesia(PCIA)with fentanyl was then started.The PCIA solution contained fentanyl 1.0 mg and droperidol 5 mg in 100 ml of normal saline.The PCA pump was set to deliver a background infusion of 0.5 ml/h and a bolus dose of 2 ml at 5 min lockout interval.The VAS score was maintained≤3.The amount of fentanyl consumed within 24 h of PCIA was recorded. Results A total of 224 patients were genotyped successfully.Among the 224 patients, there were 210 cases in group Ⅰ/Ⅰ, 6 cases in group Ⅰ/Ⅱ, 4 cases in group Ⅱ/Ⅱ, 3 cases in group Ⅰ/Ⅲ, and 1 case in groupⅠ/Ⅳ(excluded). There was no significant difference in the amount of fentanyl consumed within 24 h of PCIA among the four groups(P>0.05). Conclusion IL-1RN genetic polymorphism is not related to the hereditary factor contributing to the individual variation in the patient′s response to postoperative intravenous analgesia with fentanyl. Key words: Receptors, interleukin-1; Polymorphism, single nucleotide; Fentanyl; Analgesia; Dose-response relationship, drug