Determination of Tofacitinib in Mice Whole Blood on Dried Blood Spots Using LC–ESI–MS/MS: Application to Pharmacokinetic Study in Mice

Abstract

A simple, sensitive and rapid assay method has been developed and validated as per regulatory guideline for the estimation of tofacitinib on mice dried blood spots (DBS) using liquid chromatography coupled to tandem mass spectrometry with electro spray ionization in the positive-ion mode. The method employs liquid extraction of tofacitinib from DBS disk of mice whole blood followed by chromatographic separation using 5 mM ammonium acetate (pH 6.5):acetonitrile (20:80, v/v) at a flow rate of 0.60 mL/min on an X-Terra Phenyl column with a total run time 2.5 min. The MS/MS ion transitions monitored were 313→149 for tofacitinib and 316→149 for the internal standard (CN-tofacitinib). The assay was linear in the range of 0.99-1980 ng/mL. The intra- and inter-day precision was in the range of 1.17-10.3 and 3.37-10.9%, respectively. Stability studies showed that tofacitinib was stable on DBS cards for one month. This novel method has been applied to analyze the DBS samples of tofacitinib obtained from a pharmacokinetic study in mice.

Modeling Combined Anti-Inflammatory Effects of Dexamethasone and Tofacitinib in Arthritic Rats

“…Before disease onset, the increase of rat paw size followed the logistic growth model with hypothetical paw size at steady-state (Paw ss ) was estimated to be 98.6 mm 2 , which is comparable to 108 mm 2 found by Song et al (13) and 103 mm 2 by Li et al (16) in male CIA rats, and a 0.00103/h paw growth rate constant that is close to 0.001/h from Song et al…”

“…In humans, tofacitinib PK exhibits rapid absorption, rapid elimination, and dose-proportional systemic exposures (18), which were recapitulated in our digitized profiles. Downty et al (17) reported the time to peak concentration of TOF in humans as ranging 0.3~1.0 h and which was similar in mice (16,17). The F po of TOF was reported to be 59.4% in rats (15), 57.2% in mice (16) and 74% in humans (17,23), and the k a,po of TOF was preliminarily estimated to be 3.27, 1.36, and 3.96/h in these species.…”

“…Downty et al (17) reported the time to peak concentration of TOF in humans as ranging 0.3~1.0 h and which was similar in mice (16,17). The F po of TOF was reported to be 59.4% in rats (15), 57.2% in mice (16) and 74% in humans (17,23), and the k a,po of TOF was preliminarily estimated to be 3.27, 1.36, and 3.96/h in these species. All of the above information suggested that TOF is a well-absorbed drug.…”

“…Doses were 25 mg/kg IV and 5 mg/kg PO from Kumar et al (14) and 5 mg/kg IV and 1 mg/kg PO from Sharma et al (15) in healthy male Sprague-Dawley rats. Also, 2 mg/kg IV and 10 mg/kg PO from Dixit et al (16) in male Balb/C mice and 50 mg PO from Dowty et al (17) and 30 and 100 mg PO from Krishnaswami et al (18) in healthy adult volunteers.…”

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

“…Due to the nonavailability of deuterated filgotinib as an IS, we tried other JAK inhibitors and found that tofacitinib was found to be the best for the purpose, based on chromatographic elution, ionization, and reproducible and good extraction efficiency. For the quantitation of the IS, the MRM reaction pair of m / z 313.2 precursor ion and m / z 149.2 daughter ion was used as reported in earlier publications (Dixit, Mallurwar, Sulochana, Zainuddin, & Mullangi, ; Sharma et al, ).…”