Validation of a Dried Blood Spot Method for the Determination of a Third‐Generation Bcr‐Abl 1 Inhibitor, Vodobatinib, in Small Volumes of Rat Blood: Application to a Pharmacokinetic Study

Vodobatinib is a third-generation Bcr-Abl 1 inhibitor, being used in chronic myeloid leukemia treatment. Herein, we report a validated LC-MS/MS method for quantifying vodobatinib from rat dried blood spot (DBS) as per FDA guidelines. Methanol was used as a solvent to extract vodobatinib from the DBS discs. We used an isocratic method with a flow rate of 0.80 mL/min in an Atlantis dC₁₈ (50 × 4.6 mm, 3.0 μm) column with a 2.00 min run time. The retention of vodobatinib and the I.S. was ~1.15 and 1.05 min. The MS/MS ion transitions monitored for vodobatinib and I.S. were m/z 454.20 → 270.05 and 309.15 → 251.15, respectively. The linearity range was 1.04-1039 ng/mL. All the evaluated validation parameters met the acceptance criteria. Hematocrit levels of 35% and 50% yielded consistent concentrations at both low and high QC levels, with accuracy of 1.00%-1.03% and precision below 10%, indicating no hematocrit effect. For intravenous dosing, AUC_0-∞ was 9475 ng·h/mL (DBS) versus 10,109 ng·h/mL (plasma), and for oral dosing, C_max values were 568 ng/mL (DBS) versus 544 ng/mL (plasma). Oral bioavailability was nearly identical between matrices (98.7% for DBS vs. 97.9% for plasma), confirming the reliability of DBS sampling for PK studies of vodobatinib.