Tofacitinib
Tofacitinib. JAK1/JAK3 inhibitor — same class effect as baricitinib. Approved for RA, psoriatic arthritis, ulcerative colitis. ORAL Surveillance… Oral half-life 3.2 h.
JAK1/JAK3 inhibitor — same class effect as baricitinib. Approved for RA, psoriatic arthritis, ulcerative colitis. ORAL Surveillance trial showed worse CV + malignancy signal vs TNFi → boxed warning.
PK: all four values were zero-content on a salt-form bioequivalence study reporting only peak concentration, exposure and ratios. Two candidate collisions are logged as hypotheses: V 90 against its "90% confidence intervals", and ka 1.4 against its "up to 14 hours" of sampling. No absolute bioavailability exists — a PubMed search returns nothing and there is no human intravenous arm — so F is pinned to 1 and the volume stored as the published apparent 115.8 L, from a population fit that supplies the rate, the lag and the volume together. The stored rate of 1.4 was below every published estimate, which run 3.07 to 13.8 /h. THE EFFECT COMPARTMENT IS REMOVED AND ITS NOTE WAS WRONG IN DIRECTION: the cited paper is a RAT arthritis study containing no equilibration value, and its own conclusion attributes the effect to "attenuation of inflammation", a downstream process over days, while the note asserted equilibration with plasma. A search for any published equilibration constant for this drug returns nothing.
Pharmacokinetics
- Oral — t½ 3.2 h · F 100% · ka 9.85 h⁻¹ · Vd 115.8 L
Sources: PMID:33062629, PMID:20701804, PMID:33513294, PMID:24464803