Abstract

A high-performance liquid chromatographic assay with tandem mass spectrometric detection has been developed to simultaneously quantify lenalidomide (LEN) and dexamethasone (DEX) in human plasma to facilitate their combined clinical development. The analytes and the internal standard (IS) fluconazole were extracted from 250 μL aliquots of human plasma via liquid-liquid extraction in ethyl acetate. Chromatographic separation was achieved in a run time of 2.0 min on XTerra RP18 column (50 mmx4.6 mm, 5μm) using isocratic mobile phase, consisting of methanolwater containing 0.1% formic acid (90:10, v/v), at a flow-rate of 0.5 mL/min. Detection of analytes and IS was performed by electrospray ionisation tandem mass spectrometry, operating in positive ion and multiple reaction monitoring (MRM) acquisition mode. The protonated precursor to product ion transitions monitored for LEN, DEX and IS were m/z 260.1→148.8, 393.3→147.0 and 307.1→238.0, respectively. The method was validated over the concentration range of 9.99 to 1009.65 ngmL-1 for LEN and 1.99 -500.99 ngmL-1 for DEX in human plasma. The intra-batch and inter-batch precision (% CV) across four quality control levels was ≤ 6.4% for both the analytes. In conclusion, a simple and sensitive analytical method was developed and validated in human plasma. This method is suitable for measuring accurate concentration in clinical trial samples following combined administration of lenalidomide and dexamethasone in patients with multiple myeloma.

Keywords: Clinical trials, Dexamethasone, Lenalidomide, LC-MS/MS, Multiple myeloma, Dexamethasone (DEX), HPLC, Validation, Stability Studies