Tofacitinib Starting Dose for 13-Year-Old with Down Syndrome Associated Arthritis
The recommended starting dose of tofacitinib for a 13-year-old patient with Down syndrome associated arthritis is 5 mg twice daily. 1, 2
Dosing Considerations
Tofacitinib is a Janus kinase (JAK) inhibitor that has shown efficacy in various forms of juvenile idiopathic arthritis (JIA), including refractory cases. For adolescent patients (13 years old), the dosing approach follows these principles:
- Weight-based dosing is typically used for pediatric patients, with adolescents often receiving the adult dose of 5 mg twice daily 3
- The dose should be modified according to patient-specific factors including:
- Weight
- Comorbidities
- Concomitant medications 1
Evidence in Pediatric Populations
Clinical evidence supports the use of tofacitinib in pediatric arthritis:
- A case report of a 13-year-old with refractory systemic JIA showed complete remission after 3 months of tofacitinib therapy 2
- In the phase 3 trial for polyarticular course JIA, weight-based dosing was used with 5 mg twice daily (or equivalent lower doses based on weight) 3
- Long-term extension studies have demonstrated maintained efficacy and a consistent safety profile with tofacitinib in JIA patients up to 48 months 4
Important Monitoring and Precautions
Before initiating tofacitinib, ensure the following:
Complete pre-therapy screening:
- Tuberculosis screening (IGRA or TST and chest X-ray)
- Complete blood count with differential
- Liver function tests
- Lipid profile
- Hepatitis B and C screening 5
Verify that the patient has:
- Lymphocyte count ≥500 cells/mm³
- Absolute neutrophil count ≥1000 cells/mm³
- Hemoglobin ≥9 g/dL 5
Consider vaccination status:
- Administer live vaccines at least 4 weeks before starting therapy
- Recombinant zoster vaccine is recommended before initiating therapy 5
Ongoing Monitoring
During treatment, monitor:
- CBC with differential and liver function tests every 3-4 months
- Annual lipid profile
- Annual TB screening if in a high-risk area
- Signs of infection, particularly herpes zoster 5
Dose Adjustments
Dose adjustments may be necessary in the following circumstances:
- Moderate to severe renal impairment: reduce to 5 mg once daily
- Moderate hepatic impairment: reduce to 5 mg once daily
- Concomitant use of CYP3A4 inhibitors: reduce to 5 mg once daily 1, 5
Special Considerations for Down Syndrome
Patients with Down syndrome may have increased susceptibility to infections and other comorbidities. Therefore, careful monitoring for adverse effects is particularly important in this population.
Tofacitinib should not be combined with potent immunosuppressants or biologics used for arthritis treatment, but it can be used with methotrexate if needed 5.