title: OCT1 genetic variants influence the pharmacokinetics of morphine in children.
abstract: OBJECTIVE
  Large interindividual variability in morphine disposition could contribute to unpredictable variability in morphine analgesia and adverse events. Caucasian children have more adverse effects and slower morphine clearance than African-American children. To study variations in intravenous morphine pharmacokinetics in children, we examined the influence of genetic polymorphisms in OCT1.
  
  
  METHODS
  In 146 children undergoing adenotonsillectomy, 146 concentration-time profiles (2-4 measurements per patient) were available. Population pharmacokinetic analysis characterized the profiles in NONMEM(®) and tested OCT1 variants as covariates.
  
  
  RESULTS
  Allometrically scaled post hoc Bayesian morphine clearance in homozygotes of loss-of-function OCT1 variants (n = 9, OCT1*2-*5/*2-*5) was significantly lower (20%) than in wild-type (n = 85, OCT1*1/*1) and heterozygotes (n = 52, OCT1*1/*2-*5; p < 0.05).
  
  
  CONCLUSIONS
  Besides bodyweight, OCT1 genotypes play a significant role in intravenous morphine pharmacokinetics. Relatively high allelic frequencies of defective OCT1 variants among Caucasians may explain their lower morphine clearance and possibly higher frequencies of adverse events compared with African-American children. Original submitted 21 December 2012; Revision submitted 7 May 2013.
authors.affiliation: Division of Clinical Pharmacology, Cincinnati Children's Hospital Medical Center, OH, USA.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Fukuda
authors.forename: Vidya
authors.initials: V
authors.lastname: Chidambaran
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Mizuno
authors.forename: Raja
authors.initials: R
authors.lastname: Venkatasubramanian
authors.forename: Pornswan
authors.initials: P
authors.lastname: Ngamprasertwong
authors.forename: Vanessa
authors.initials: V
authors.lastname: Olbrecht
authors.forename: Hope R
authors.initials: HR
authors.lastname: Esslinger
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Vinks
authors.forename: Senthilkumar
authors.initials: S
authors.lastname: Sadhasivam
mesh_terms: D001741:Black or African American / Q000235:genetics; D002648:Child; D005260:Female; D056726:Genetic Association Studies; D005838:Genotype; D006801:Humans; D008297:Male; D009020:Morphine / Q000493:pharmacokinetics / Q000627:therapeutic use*; D027702:Organic Cation Transporter 1 / Q000235:genetics*; D010149:Postoperative Pain / Q000235:genetics; D011110:Polymorphism, Genetic; D044465:White People / Q000235:genetics
chemical_list: D027702:Organic Cation Transporter 1; D009020:Morphine