Dasotraline is a dopamine and norepinephrine reuptake inhibitor, and the early clinical trials show a slow absorption and long elimination half‐life. To investigate the absorption, distribution, metabolism, and excretion of dasotraline in humans, a single dose of [14C]‐dasotraline was administered to eight healthy male adult volunteers. At 35 days, 90.7% of the dosed radioactivity was recovered in the urine (68.3%) and feces (22.4%). The major metabolic pathways involved were: (1) amine oxidation to form oxime M41 and sequential sulfation to form M42 or glucuronidation to form M43; (2) N‐hydroxylation and sequential glucuronidation to form M35; (3) oxidative deamination to form (S)‐tetralone; (4) mono‐oxidation of (S)‐tetralone and sequential glucuronidation to form M31A and M32; and (5) N‐acetylation to form (1R,4S)‐acetamide M102. A total of 8 metabolites were detected and structurally elucidated with 4 in plasma (M41, M42, M43, and M35), 7 in urine (M41, M42, M43, M31A, M32, M35, and (S)‐tetralone), and 3 in feces (M41, (S)‐tetralone, and (1R,4S)‐acetamide). The 2 most abundant circulating metabolites were sulfate (M42) and glucuronide (M43) conjugates of the oxime of dasotraline, accounting for 60.1% and 15.0% of the total plasma radioactivity, respectively; unchanged dasotraline accounted for 8.59%. The oxime M41 accounted for only 0.62% of the total plasma radioactivity and was detected only at early time points. M35 was a minor glucuronide metabolite, undetectable by radioactivity but identified by mass spectrometry. The results demonstrate that dasotraline was slowly absorbed, and extensively metabolized by oxidation and subsequent phase II conjugations. The findings from this study also demonstrated that metabolism of dasotraline by humans did not produce metabolites that may cause a safety concern.

Calculated profile mode mass spectrometry (MS) data are fitted to lineshape‐calibrated liquid chromatography LC/MS data using a Multiple Linear Regression (MLR) model to quantitate the relative concentrations of stable or radiolabeled compound mixtures. This alternative approach significantly improves the precision and accuracy over existing MS methods while providing the much‐needed statistical diagnostics on the goodness‐of‐fit model and thus reliability of the quantitative results obtained. Test compound data containing S/Cl atoms have been measured with either stable deuterium labeling or radioisotope uniform 14C labeling onto an aromatic ring. Since the entire relative distribution of variously labeled compounds is automatically obtained through this approach, it is feasible to directly calculate the Specific Activity (SA) from such mass spectral analysis without radioactivity detection and the usual standard curve quantitation. The applicability of this approach to systematically and accurately accommodate and account for incomplete labeling chemistry or other impurities is also discussed, with wide‐ranging implications including metabolic flux, HDX (Hydrogen/Deuterium Exchange), and quantitative proteomics.

No abstract

No abstract