Prevalence of opioid glucuronides in human hair

Current hair testing methods, which mainly rely on quantification of parent drug analytes, have difficulty distinguishing drug deposited into hair through physiological processes from drug deposited onto hair via external contamination. Using conjugated phase II metabolites to differentiate between drug use and possible external contamination is advantageous as they are unlikely to be degradation products or synthesis byproducts. In this study, 97 specimens were analyzed for opioid glucuronides and the corresponding parent drugs. Morphine-3-glucuronide and morphine-6-glucuronide were the most prevalent glucuronides and were detected in 82 % of specimens with morphine concentrations ≥ 200 pg/mg (n = 33). Median glucuronide to parent ratios were 0.65 % and 1.12 % for morphine-3-glucuonide and morphine-6-glucuronide respectively. Codeine-6-glucuronide was detected in 100 % of specimens with a codeine concentration ≥ 200 pg/mg (n = 8), with a median glucuronide to parent ratio of 2.21 %. Hydromorphone-3-glucuronide was detected in 75 % of specimens with hydromorphone ≥ 200 pg/mg (n = 4) with a median glucuronide to parent ratio of 1.24 %. Oxycodone-3-glucuronide was detected in 37 % of specimens with oxycodone ≥ 200 pg/mg with a median glucuronide to parent ratio of 0.91 %. No hair specimens with a parent concentration less than LOD had a corresponding glucuronide present. This study shows that a 1 pg/mg cutoff for glucuronides provides similar sensitivity as the currently recommended 200 pg/mg cutoff for morphine, codeine, and hydrocodone.