Antidepressant drugs in oral fluid using liquid chromatography-tandem mass spectrometry

An analytical procedure for the determination of widely prescribed drugs for the treatment of depression and anxiety disorders, including amitriptyline, cyclobenzaprine, imipramine, dothiepin, doxepin, fluoxetine, sertraline, trimipramine, protriptyline, chlorpromazine, clomipramine, and some of their metabolites (nortriptyline, desmethyldoxepin, desipramine, desmethyltrimipramine, norclomipramine) in oral fluid has been developed and validated using liquid chromatography with tandem mass spectral detection. The oral fluid samples were collected using the Quantisal device and screened with enzyme-linked immunosorbent assay. Any drugs present were quantified using mixed-mode solid-phase extraction followed by mass spectrometric detection in positive electrospray ionization mode. For confirmation, two transitions were monitored, and the ratio between the two was required to be within 20% of the known calibration standard. Because of the worldwide shortage of acetonitrile, which was first reported in October 2008, the mobile phase was optimized to use methanol as the organic component. For all compounds, the lower limit of quantitation was 5 ng/mL; the intraday precision ranged from 2.9 to 8.2% (n = 6); interday precision from 1.5 to 6.2% (n = 30) at a concentration of 40 ng/mL. The percentage recovery of antidepressants from the oral fluid collection pad was calculated at a concentration of 40 ng/mL and ranged from 51.4 to 84.1% (n = 6). The aim of the study was to develop a confirmatory procedure for drugs in oral fluid that had been identified as presumptively positive for antidepressants and related compounds. The methods were applied to research oral fluid specimens received into our facility for testing.