Prescription opioids. II. metabolism and excretion patterns of hydrocodone in urine following controlled single-dose administration

Hydrocodone (HC) is a highly misused prescription drugs in the USA. Interpretation of urine tests for HC is complicated by its metabolism to two metabolites, hydromorphone (HM) and dihydrocodeine (DHC), which are also available commercially and are misused. Currently, there is interest in including HC and HM in the federal workplace drug-testing programs. This study characterized the disposition of HC in human urine. Twelve healthy, drug-free, adults were administered a single, oral 20 mg immediate-release dose of HC in a controlled clinical setting. Urine specimens were collected at timed intervals for up to 52 h and analyzed by LC-MS-MS (limit of quantitation 5 50 ng/mL) with and without enzymatic hydrolysis. All specimens were also analyzed for creatinine and specific gravity (SG). HC and norhydrocodone (NHC) appeared within 2 h followed by HM and DHC. Peak concentrations of HC and metabolites occurred at 3-9 h. Peak hydrolyzed concentrations were in the order: NHC > HC > HM > DHC. Only HM was excreted extensively as a conjugated metabolite. At a cutoff concentration of 50 ng/mL, detection times were ~28 h for HC, 40 h for NHC, 26 h for HM and 16 h for DHC. Some specimens did not contain HC, but most contained NHC, thereby facilitating interpretation that HC was the administered drug. Creatinine and SG measures were highly correlated. Creatinine corrections of HC urinary data had variable effects of lowering or raising concentrations. These data suggest that drug-testing requirements for HC should include a hydrolysis step and a test for HM.