Table 4.

Urinary nicotine equivalents and metabolite ratios by UGT2B10 genotype: geometric means and 95% CI

UGT2B10 GenotypeCotinine glucuronidation ratio*Nicotine glucuronidation ratio*Total trans-3′-hydroxycotinine to free cotinineNicotine equivalents
Wild-type (N = 264)2.03 (1.86-2.20)0.77 (0.64-0.89)3.80 (3.96-4.15)69.2 (64.3-74.5)
Asp67Tyr§ (N = 63)1.26 (1.00-1.56)0.41 (0.25-0.62)3.96 (3.35-4.64)58.2 (48.9-68.2)
P < 0.0001P = 0.005P = 0.715P = 0.048
  • *Glucuronide conjugate to unconjugated analyte ratio.

  • Total trans-3′-hydroxycotinine to total cotinine ratio was higher among Asp67Tyr heterozygotes compared with wild-type: 1.73 (1.46-2.03) versus 1.29 (1.18-1.41), P = 0.003, adjusted for nicotine equivalents.

  • Sum of nicotine, cotinine, trans-3′-hydroxycotinine, and their respective glucuronides in nmol/mL, quantified in first morning urine. Urinary nicotine N-oxide was quantified in a subset of individuals (n = 108; study 1) and did not differ by genotype: mean, 4.03 ± 2.8 nmol/mL; range, 0.08-14.5 nmol/mL.

  • §UGT2B10 Asp67Tyr heterozygous individuals.

  • Adjusted for nicotine equivalents.