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Tofacitinib (Xeljanz)

JAK Inhibitorprescriptionoral · inferred

First-in-class oral Janus kinase inhibitor with JAK1/JAK3 > JAK2 selectivity. Approved for rheumatoid arthritis, psoriatic arthritis, ulcerative colitis, polyarticular JIA, and ankylosing spondylitis. Typical 5 mg PO BID (or 11 mg XR QD); UC induction 10 mg BID then 5 mg BID maintenance. Plasma half-life ~3h supports BID IR dosing. Oral bioavailability ~74%. CYP3A4 metabolism (plus CYP2C19). FDA boxed warning: MACE, thrombosis, malignancy, serious infection, especially in RA patients >50 with cardiovascular risk factors (ORAL Surveillance).

Projected serum levels — 5 mg, twice daily

Tofacitinib (Xeljanz)
Tofacitinib (Xeljanz) modeled serum levels, 5 mg twice daily over 15 days Population-based pharmacokinetic estimate. Steady state reached after approximately 1 days. 0 1.3 2.5 3.8 5 Day 0 Day 4 Day 7 Day 11 Day 15 Time on a regular schedule ≈ steady state · day 1

Maintenance schedule: 5 mg twice daily (oral).

Modeled steady state after ~1 days: peak ≈ 3.2 mg, trough ≈ 0.27 mg body load. Population-based estimate over 15 days for a 5 mg dose at a 70 kg reference body mass — the interactive app scales curves to your doses, timing, and body mass.

Key facts

Category
JAK Inhibitor
Route modeled
Oral
Model confidence
inferred
Half-life
3 h
Common dose
5 mg
Suggested maximum
20 mg/day
Reference dose range
2.5–20 mg (single dose)
Suggested cadence
twice daily
Validated against
5 mg oral — Cmax 0.050 mg/L at 1 h

Documented interactions

  • contraindicated
    Efavirenz (Sustiva) + Tofacitinib (Xeljanz) CYP induction

    Efavirenz (Sustiva) inducer of CYP3A4 predicted to change Tofacitinib (Xeljanz) AUC by ~0.16x

  • contraindicated
    Rifampin + Tofacitinib (Xeljanz) CYP induction

    Rifampin inducer of CYP3A4 predicted to change Tofacitinib (Xeljanz) AUC by ~0.16x

  • danger
    Amlodipine (Norvasc) + Tofacitinib (Xeljanz) CYP inhibition

    Amlodipine (Norvasc) reversible_inhibitor of CYP3A4 predicted to change Tofacitinib (Xeljanz) AUC by ~2.05x

  • danger
    Ashwagandha (KSM-66) + Tofacitinib (Xeljanz) CYP inhibition

    Ashwagandha (KSM-66) reversible_inhibitor of CYP3A4 predicted to change Tofacitinib (Xeljanz) AUC by ~2.05x

  • danger
    Berberine + Tofacitinib (Xeljanz) CYP inhibition

    Berberine reversible_inhibitor of CYP3A4 predicted to change Tofacitinib (Xeljanz) AUC by ~2.05x

  • danger
    Black Seed Oil (Nigella sativa / Thymoquinone) + Tofacitinib (Xeljanz) CYP inhibition

    Black Seed Oil (Nigella sativa / Thymoquinone) reversible_inhibitor of CYP3A4 predicted to change Tofacitinib (Xeljanz) AUC by ~2.05x

Serum checks 95 modeled interaction pairings for tofacitinib (xeljanz) across your whole stack — absorption conflicts, enzyme inhibition, and nutrient depletion included.

Research behind this entry

  1. Preclinical to clinical translation of tofacitinib, a Janus kinase inhibitor, in rheumatoid arthritis Dowty ME et al. · Drug Metabolism and Disposition, 2014 DOI

    Translational PK/PD study: t1/2 ~3h, oral F ~74%, CYP3A4/2C19 metabolism, and exposure-response in RA.

  2. Placebo-controlled trial of tofacitinib monotherapy in rheumatoid arthritis (ORAL Standard) Fleischmann R et al. · New England Journal of Medicine, 2012 DOI

    Pivotal ORAL Standard phase 3 trial demonstrating tofacitinib 5 mg and 10 mg BID efficacy in methotrexate-IR RA.

2 published studies referenced in the app, each with a plain-language summary.