A sensitive liquid chromatography-tandem mass spectrometry method for quantitative determination of dasotraline in...

This manuscript describes a highly sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of dasotraline in human plasma. Dasotraline and the internal standard (IS) d₄-¹³C₄-dasotraline were extracted from the 0.500-mL plasma pre-mixed with 0.20-mL of 0.5 M sodium bicarbonate solution by a 3-mL of hexane containing 0.7 % sec-butyl alcohol. The organic extract, after dried down, was reconstituted in 150 μL acetonitrile containing 0.1 % formic acid. Forty (40) μL of the resulted sample was injected into LC-MS/MS for analysis. Chromatographic separation was on a Betasil Silica column. MS/MS detection was by monitoring m/z 275→159 and 283→160 for dasotraline and IS, respectively. Peak area ratio of analyte/IS was used for constructing calibration curve and calculating sample concentration. The retention time was ∼3.1 min for both dasotraline and IS. The validated linear range was 5-5000 pg/mL with correlation coefficient r ≥ 0.999. Intra-run precision and accuracy were ≤ 7.3 % CV (n = 6) and 94.4-101.0 % of nominals. Inter-run precision and accuracy were ≤ 4.7 % CV (n = 18) and 96.1-99.8 % of nominals. Plasma sample was confirmed stable for 8 cycles of freeze/thaw, 29 h on bench-top, and up to 977 days of storage at both -20 °C and -70 °C. This method was successfully applied to analyze pharmacokinetic (PK) samples from a single ascending dose (SAD) clinical study with healthy subjects. PK results indicated that dasotraline was slowly absorbed (t_max: 10-12 h) and slowly eliminated (terminal elimination half-life, i.e. t_1/2: 47-77 h) with dose proportional C_max but slightly greater than dose proportional AUC with increase of dosed amount.