Simultaneous quantification of thalidomide, lenalidomide and pomadomide in plasma by LC-MS/MS

To develop a new method for quantitatively analyzing three immunomodulators (thalidomide, lenalidomide and pomadomide) by liquid chromatography tandem mass spectrometry (LC-MS/MS).

Using thalidomide-d4 as internal standard, the three analytes were separated on Agilent Zorbax SB-C18(2.1 mm × 100 mm, 3.5 μm, Agilent, USA) column and monitored in multiple reactions monitoring mode in Agilent G6460A triple quadrupole mass spectrometer operating in positive ionization mode. The sample was pretreated by protein precipitation using methanol at 3-fold volume to sample. The mobile phase was comprised of 0.1% formic acid in water (phase A) and acetonitrile (phase B) and was delivered in gradient elution program. The flow rate was 0.3 mL/min, and the injection volume was 5 μL.

The accuracy and stability of the method are within ±15.0%, and the precision is not >15.0%. The recoveries were 85.04% ∼ 119.07%, and the matrix effect was 73.68% ∼ 116.75%. Specificity, linearity, LLOQ, carry-over and dilution were all in line with the requirements of pharmacopeia and guidelines. The peak concentrations of thalidomide, lenalidomide shows huge inter-individual differences.

This newly developed method was sensitive, simple, and robust and can be used in therapeutic drug monitoring of three immunomodulators in multiple myeloma patients.