Validated LC–MS/MS method for quantitation of a selective JAK1 inhibitor, filgotinib in rat plasma, and its application to a pharmacokinetic study in rats

Abstract

Filgotinib is a selective JAK1 (Janus kinase) inhibitor, filed in Japan for the treatment of rheumatoid arthritis. In this paper, we report a validated liquid chromatography coupled with tandem mass spectrometry for the quantification of filgotinib in rat plasma using tofacitinib as an internal standard (IS) as per the Food and Drug Administration regulatory guidelines. Filgotinib and the IS were extracted from rat plasma using ethyl acetate as an extraction solvent and chromatographed using an isocratic mobile phase (0.2% formic acid:acetonitrile; 20:80, v/v) at a flow rate of 0.9 mL/min on a Gemini C18 column. Filgotinib and the IS were eluted at ~1.31 and 0.89 min, respectively. The MS/MS ion transitions monitored were m/z 426.3 → 291.3 and m/z 313.2 → 149.2 for filgotinib and the IS, respectively. The calibration range was 0.78–1924 ng/mL. No matrix effect and carryover were observed. Intra‐ and inter‐day accuracies and precisions were within the acceptance range. Filgotinib was stable for three freeze–thaw cycles: on bench‐top up to 6 h, in an autosampler up to 21 h, and at −80°C for 1 month. This novel method has been applied to a pharmacokinetic study in rats.

Novel methodology to perform incurred sample reanalysis on dried blood spot cards: Experimental data using darolutamide and filgotinib

“…One‐half was used for half‐DBS ISR analysis and the other half was divided further into two halves to get quarter‐DBS disc and subsequently used for ISR analysis (Figure 1). All the DBS discs (full, half and quarter) were processed in similar lines as mentioned in the following section for the quantitation of respective drugs [see Saini, Sulochana, Zainuddin, & Mullangi (2018) for darolutamide and Dixit, Kiran, Gabani, & Mullangi (2020) for filgotinib]. ISR of all DBS discs (full, half and quarter) was done on day 50.…”

Validated DBS method for filgotinib quantitation in rat dried blood spots and its application to a pharmacokinetic study in rats

“…We used the similar chromatographic conditions that we previously reported [ 10 ]. In brief, a Gemini C18 (100 × 4.6 mm, 3 μm) column maintained at ambient room temperature along with an isocratic mobile phase (0.2% formic acid in Milli-Q water:acetonitrile, 20:80, v/v) at a flow-rate of 0.9 mL/min was used for separation of filgotinib and the IS.…”

“…The authors have attained an LLOQ of 0.78 ng/mL with 50 μL rat plasma. Plasma samples were processed using ethyl acetate as an extraction solvent [ 10 ].…”

DBS Assay with LC-MS/MS for the Determination of Idelalisib, A Selective PI3K-δ Inhibitor in Mice Blood and Its Application to a Pharmacokinetic Study

“…Dried blood spot (DBS) methodology is becoming a valuable tool in recent times for the quantitative analysis of various drugs [11][12][13][14][15][16][17][18]. DBS offers several advantages over traditional sampling (plasma/blood/serum) techniques namely reduction of commercial costs for laboratory equipment, convenience in collection, reduction in collection of blood volume, no requirement of a trained phlebotomist, ease of sample handling/storage/shipping, safety in handling, less time in processing and increase in throughput etc.…”