The Pharmacokinetics, Metabolism, and Clearance Mechanisms of Tofacitinib, a Janus Kinase Inhibitor, in Humans
The PK of tofacitinib has previously been described in several papers covering a range of diseases. This current study was used to better understand the PK, metabolism and clearance mechanisms of tofacitinib in healthy human subjects.
Six subjects took a single 50mg dose of 14C-tofacitinib orally and consequently had urine, faeces and plasma collected. These were assayed for radioactivity and profiled for metabolites.
Tofacitinib was found to be rapidly absorbed, with peak plasma concentrations and total radioactivity peaking at one hour after dosing. Most of the radioactivity measured in the plasma was from the parent drug, with metabolites representing <10% each of measured radioactivity.
Overall, this pharmacokinetic characterisation of tofacitinib was consistent with clinical experience in drug-drug interaction studies.