title: Effect of the CYP2D6*10 C188T polymorphism on postoperative tramadol analgesia in a Chinese population.
abstract: OBJECTIVE
  The CYP2D6*10 allele is the most common allele with a frequency ranging from 51.3 to 70% and correlated with a significantly reduced metabolic activity in a Chinese population. The aim of the present study was to investigate whether the CYP2D6*10 allele has an impact on the postoperative analgesia effect of tramadol in Chinese patients recovering from major abdominal surgery.
  
  
  METHODS
  A prospective study design was used and 70 gastric cancer patients recovering from gastrectomy were enrolled. After receiving a loading dose i.v., patients could self-administer doses of the drug combination (10 mg/ml tramadol plus 0.3 mg/ml metoclopramide) via patient-controlled analgesia (PCA). Blood samples were collected after induction of anesthesia. The CYP2D6*10 C188T polymorphism was analyzed by means of polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP). Demographic data among groups with different genotypes were analyzed using analysis of variance. The total consumption of tramadol between the three genotype groups for 48 h was compared.
  
  
  RESULTS
  The allele frequency of CYP2D6*10 is 52.4%; patients were categorized into three groups according to the CYP2D6 genotype: patients without CYP2D6*10 (group I, n=17), patients heterozygous for CYP2D6*10 (group II, n=26), and patients homozygous for CYP2D6*10 (group III, n=20). The demographic data among the three groups were comparable. The total consumption of tramadol for 48 h in group III was significantly higher than that in groups I and II, while it did not differ between groups I and II.
  
  
  CONCLUSIONS
  This study indicates that the CYP2D6*10 allele has significant impact on analgesia with tramadol in a Chinese population. Pharmacogenetics may explain some of the varying responses to pain medication in postoperative patients.
authors.affiliation: Department of Anaesthesiology, First Affiliated Hospital, School of Medicine, Zhejiang University, No. 79, Qing Chun Road Hangzhou, Zhejiang, 310003, China.
authors.forename: GuoXiang
authors.initials: G
authors.lastname: Wang
authors.forename: Hui
authors.initials: H
authors.lastname: Zhang
authors.forename: FeiFang
authors.initials: F
authors.lastname: He
authors.forename: XiangMing
authors.initials: X
authors.lastname: Fang
mesh_terms: D000483:Alleles; D000701:Analgesics, Opioid / Q000627:therapeutic use*; D000704:Analysis of Variance; D044466:Asian People; D019389:Cytochrome P-450 CYP2D6 / Q000235:genetics*; D005260:Female; D005743:Gastrectomy; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D010149:Postoperative Pain / Q000188:drug therapy* / Q000235:genetics*; D010597:Pharmacogenetics; D011110:Polymorphism, Genetic; D011446:Prospective Studies; D013274:Stomach Neoplasms / Q000601:surgery; D014147:Tramadol / Q000627:therapeutic use*
chemical_list: D000701:Analgesics, Opioid; D014147:Tramadol; D019389:Cytochrome P-450 CYP2D6