Urine specimens from pain management patients dosed with Nucynta (Tapentadol) were confirmed for the presence of tapentadol and N-desmethyltapentadol using ultra-performance liquid chromatography-tandem mass spectrometry to minimize sample preparation and urine volume requirements. The linearity of the method for both tapentadol and N-desmethyltapentadol demonstrated correlation coefficients (R²) above 0.99 and linear ranges from 50 to 500,000 ng/mL for tapentadol and 100 to 500,000 ng/mL for N-desmethyltapentadol. The intraday precision of the assay for both analytes ranged from 2.2 to 6.9% over three concentrations; the interday precision for both analytes ranged from 1.2 to 8.4%. The limits of quantitation were 50 and 100 ng/mL for tapentadol and N-desmethyltapentadol, respectively, and the upper limit of linearity for both analytes was determined to be 500,000 ng/mL. Urine samples were collected within 24 h of dosing with tapentadol and shipped overnight to the laboratory. Samples were hydrolyzed with acid prior to analysis to measure total (unconjugated and conjugated) tapentadol and N-desmethyltapentadol. Further investigation into characterization of metabolites was performed by using a hybrid quadrupole-time-of-flight mass spectrometer in lieu of suitable analytical reference standards. The presence of significant N-desmethyltapentadol glucuronide was demonstrated for the first time.

A substantial incidence of positive methadone screens for pain management urine specimens using a commercial enzyme immunoassay (EIA) was observed in the absence of a methadone prescription, with negative methadone confirmation by ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS-MS). Tapentadol was the only common prescription among the investigated specimens. Tapentadol or one of its three major metabolites was tested at various concentrations (100-200,000 ng/mL) against the DRI EIAs for methadone and methadone metabolite, to evaluate cross-reactivity. Ninety-seven authentic tapentadol urine specimens that produced false-positive methadone EIA results (cutoff = 130 ng/mL) were analyzed for methadone and tapentadol in compound-specific UPLC-MS-MS confirmation tests. Tapentadol, tapentadol glucuronide, tapentadol sulfate and N-desmethyltapentadol exhibited cross-reactivity with the methadone EIA at 6,500 (2.2%), 25,000 (0.6%), 3,000 (4.4%) and 20,000 ng/mL (0.9%), respectively. No cross-reactivity was observed with the methadone metabolite 2-ethylidine-1,5-dimethyl-3,3-diphenylpyrrolidine EIA. All authentic urine specimens were confirmed to be negative for methadone, but positive for tapentadol and all monitored metabolites. Individual concentrations indicated that separate or combined urinary concentrations of tapentadol and its conjugates may produce false-positive methadone screens through cross-reactivity with the methadone immunoassay. The potential for false-positive results for methadone EIA screening of urine specimens associated with tapentadol prescriptions should be considered when interpreting results.