Table 3.

Pharmacokinetic variables of [2-13C]uracil catabolism correlate with DPD activity and the UraBT

DPD activity (nmol/min/mg)*UraBT DOB50 (DOB)*
[2-13C]Uracil CL/F (mL/min/kg)0.670.59
[2-13C]Uracil AUCτ (min μg/mL)−0.72−0.73
[2-13C]Uracil t1/2 (min)−0.54−0.59
[2-13C]Uracil metabolized (%)0.670.77
[2-13C]Dihydrouracil appearance rate (μg/mL/min)0.590.76
[2-13C]Dihydrouracil formed (mg)0.610.82
DUUR0.670.65
[2-13C]Dihydrouracil Cmax (μg/mL)0.430.70
[2-13C]Dihydrouracil Tmax (min)−0.64−0.68
  • * All Pearson correlation coefficients (rp) are significant (all Ps < 0.05).

  • DUUR, ratio of plasma dihydrouracil AUC/uracil AUC; Cmax, maximum concentration of [2-13C]dihydrouracil in plasma.