Tofacitinib (Xeljanz) is an oral Janus kinase inhibitor indicated for the treatment of various autoimmune diseases, including rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, ulcerative colitis, and juvenile idiopathic arthritis in children.
How to Use Tofacitinib (Xeljanz)
Administration Time and Method
Immediate-release tablets and oral solution: Administer twice daily, either with food or on an empty stomach.
Extended-release tablets: Administer once daily; swallow the tablets whole. Do not chew, crush, or split them.
Oral solution: Use the accompanying dosing syringe to measure the dose accurately. Any unused portion must be discarded within 60 days after the first use.
Dosage Form Conversion
Immediate-release tablets and extended-release tablets are not interchangeable. Conversion between the two should be carried out under the guidance of a doctor.
Example: When switching from 5 mg immediate-release tablets (twice daily) to 11 mg extended-release tablets (once daily), start the extended-release tablets on the day after the last dose of the immediate-release tablets.
Dosage Adjustment of Tofacitinib (Xeljanz)
Adjustment Based on Renal Function
Mild renal impairment: No dosage adjustment is required.
Moderate renal impairment (for adult patients with RA, PsA, AS): Reduce the dose of immediate-release tablets to 5 mg once daily; extended-release tablets are not recommended.
Pediatric patients or patients with UC: Reduce the dose by half accordingly.
Severe renal impairment or patients on dialysis: Further reduce the dose. For patients on dialysis, administer the medication after dialysis.
Adjustment Based on Hepatic Function
Mild hepatic impairment: No dosage adjustment is required.
Moderate hepatic impairment: Reduce the adult dose to 5 mg once daily; extended-release tablets are not recommended.
Severe hepatic impairment: Use is contraindicated.
Concomitant Use with Other Medications
When used concomitantly with strong CYP3A4 inhibitors (e.g., ketoconazole) or moderate CYP3A4 + strong CYP2C19 inhibitors (e.g., fluconazole), reduce the dose by half.
Concomitant use with strong CYP3A4 inducers (e.g., rifampicin) is not recommended.
Dosage Adjustment for Laboratory Abnormalities
Lymphocytes < 500/mm³: Discontinue the medication.
Neutrophils 500-1000/mm³: Suspend the medication; treatment can be resumed once neutrophils recover.
Neutrophils < 500/mm³: Discontinue the medication.
Hemoglobin < 8 g/dL or a decrease of > 2 g/dL: Suspend the medication; treatment can be resumed once hemoglobin recovers.
Precautions for Tofacitinib (Xeljanz) Use in Special Populations
Pediatric Patients
Aged 2 years and older: Indicated for psoriatic arthritis and polyarticular juvenile idiopathic arthritis.
Weight-based dosing:
10 to < 20 kg: 3.2 mg (3.2 mL of oral solution) twice daily.
20 to < 40 kg: 4 mg (4 mL of oral solution) twice daily.
≥ 40 kg: 5 mg (either tablets or 5 mL of oral solution) twice daily.
Aged under 2 years: The efficacy has not been established.
Elderly Patients
Elderly patients have a higher risk of infection and should be closely monitored.
Data on the use in patients with ulcerative colitis, psoriatic arthritis, and ankylosing spondylitis are limited, requiring individualized assessment.
Pregnancy and Lactation
Pregnancy: Animal studies have shown embryotoxicity; human data are limited, and use is not recommended.
Lactation: The drug can pass into breast milk. It is recommended to discontinue breastfeeding during treatment and for 18 hours (for immediate-release formulations) or 36 hours (for extended-release tablets) after the last dose.
Patients with Hepatic or Renal Impairment
Patients with moderate to severe hepatic or renal impairment require dosage adjustment; use is contraindicated in patients with severe impairment.
Patients on dialysis should take the medication after dialysis, and no supplementary dose is needed.
