Determination of a novel anti‐influenza pinanamine‐based analog in rat plasma by liquid chromatography‐tandem mass spectrometry and its application in pharmacokinetic evaluations

A pinanamine‐based analog, (1R,2R,3R,5S)‐N‐((3‐cyclopropylthiophen‐2‐yl)methyl)‐2,6,6‐trimethylbicyclo[3.1.1]heptan‐3‐amine (M090) was synthesized and demonstrated with anti‐influenza activity to overcome the multi‐drug resistance. Herein, a rapid and robust liquid chromatography‐tandem mass spectrometry method was developed and validated to quantify M090 in rat plasma. With simple protein precipitation by methanol, the separation of M090 was performed on a Waters BEH‐C18 column (2.1 × 100 mm, 1.7 μm) by gradient elution at 0.4 mL/min with mobile phases consisting of water containing 0.1 % formic acid (phase A) and methanol (phase B). M090 and clenbuterol (internal standard) were detected using multiple reaction monitoring in positive electrospray ionization mode with transitions of m/z 290.3→137.0 and m/z 277.0→203.0, respectively. The method was validated over a linear range of 1.0–2400 ng/mL with a regression coefficient of 0.9974 and no endogenous interference. The intra‐ and inter‐batch precisions were within 8.29% and accuracy ranged from 100.3% to 108.1% for M090. The validated method was utilized to evaluate the in vitro metabolic stability and in vivo pharmacokinetics of M090 in rats.