Postmortem distribution of tapentadol and N-desmethyltapentadol.

Postmortem distribution concentrations of the pain medication tapentadol and its metabolite N-desmethyltapentadol are reported. Tapentadol (Nucynta®) is a synthetic mu-opioid receptor agonist that also has norepinephrine reuptake inhibitor action. The laboratory received two cases. Case 1: a 19-year-old, morbidly obese male with sudden unexpected death. Toxicology results revealed tapentadol (femoral blood: 0.77 mg/L, liver: 1.65 mg/kg), N-desmethyltapentadol (femoral blood: 0.07 mg/L, liver: 0.19 mg/kg), diazepam (femoral blood: 0.04 mg/L), nordiazepam (femoral blood: 0.06 mg/L) and amiodarone (femoral blood: 5.30 mg/L). Case 2: a 60-year-old female who died from complications following hip replacement. Only tapentadol (femoral blood: 0.26 mg/L, liver: 0.52 mg/kg) was found in the toxicology results. Quantitative results of tapentadol/N-desmethyltapentadol were achieved using liquid chromatography-tandem mass spectrometry in multiple reactions monitoring mode. This is the first known distribution study of tapentadol and N-desmethyltapentadol values in postmortem cases.