Bioanalytical method development, validation and quantification of dorsomorphin in rat plasma by LC-MS/MS

The present investigation describes the development and validation of a sensitive liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) method for the estimation of dorsomorphin in rat plasma. A sensitive LC-MS/MS method was developed using multiple reaction monitoring mode, with the transition of m/z (Q1/Q3) 400.2/289.3 for dorsomorphin and m/z (Q1/Q3) 306.2/236.3 for zaleplon. Chromatographic separation was achieved on a reverse phase Agilent XDB C18 column (100 × 4.6 mm, 5 µm). The mobile phase consisted of acetonitrile and 5 mm ammonium acetate buffer (pH 6.0) 90:10 v/v, at a flow rate of 0.8 mL/min. The effluence was ionized in positive ion mode by electrospray ionization (ESI) and quantitated by mass spectrometry. The retention times of dorsomorphin and internal standard were found to be 2.13 and 1.13 min, respectively. Mean extraction recovery of dorsomorphin and internal standard in rat plasma was above 80%. Dorsomorphin calibration curve in rat plasma was linear (r(2) ≥ 0.99) ranging from 0.005 to 10 µg/mL. Inter-day and intra-day precision and accuracy were found to be within 85-115% (coefficient of variation). This method was successfully applied for evaluation of the oral pharmacokinetic profile of dorsomorphin in male Wistar rats.