Journal of analytical toxicology
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Hydrocodone combined with acetaminophen is commonly used for moderate pain. Hydrocodone is metabolized by cytochrome P450 (CYP) 2D6 into hydromorphone and by CYP3A4 into norhydrocodone. This was a retrospective study evaluating hydrocodone, hydromorphone and norhydrocodone distributions in urine. ⋯ Hydrocodone mole fractions were higher in the 65-year and older age group compared with the 16- to 39-year age group (0.4 versus 0.36; P ≤ 0.005). Concurrent use of a CYP2D6 and/or CYP3A4 inhibitor altered hydromorphone and norhydrocodone mole fractions, compared with the control group. Patient factors affect hydrocodone and metabolite mole fractions and suggest increased awareness of their contribution when attempting to interpret urine drug testing results.