Jakafi
Clinical Notes
Jakafi (ruxolitinib) is a JAK1/JAK2 inhibitor used for myeloproliferative neoplasms and graft-versus-host disease.
| Indication | Intermediate or high-risk myelofibrosis; polycythemia vera inadequately controlled by hydroxyurea; steroid-refractory acute and chronic graft-versus-host disease (GVHD) |
| Mechanism of Action | Inhibits Janus kinases JAK1 and JAK2, blocking JAK-STAT signaling pathway that is dysregulated in myeloproliferative neoplasms and GVHD inflammatory responses |
| Pharmacokinetics | Bioavailability ~95%; peak 1-2 hours; half-life 3-5 hours; 97% protein bound; hepatic metabolism via CYP3A4 (major), CYP2C9; renal excretion (74%); active metabolites contribute to effect |
| Dosing | Myelofibrosis: Based on platelet count—20 mg BID if >200K, 15 mg BID if 100-200K, 5 mg BID if 50-100K; PV: 10 mg BID; GVHD: 5-10 mg BID; adjust for renal/hepatic impairment and CYP3A4 interactions |
| Contraindications | No absolute contraindications; use with caution in severe renal or hepatic impairment, active infections |
| Adverse Effects | Thrombocytopenia, anemia, neutropenia, infections (including opportunistic—TB, PML, hepatitis B reactivation), bruising, dizziness, headache, non-melanoma skin cancer, weight gain |
| Drug Interactions | Strong CYP3A4 inhibitors (ketoconazole) increase levels—reduce dose by 50%; fluconazole requires dose reduction; strong CYP3A4 inducers decrease levels—may need dose increase |
| Monitoring | CBC with differential at baseline, every 2-4 weeks until stable, then as indicated; LFTs; renal function; screen for TB and hepatitis B before starting; signs of infection |
| Other Considerations | Do not abruptly discontinue (may cause return of symptoms/cytokine storm); taper over 1-2 weeks; can be given with or without food; reduces spleen size and constitutional symptoms |
| Reference | Jakafi prescribing information; COMFORT trials; REACH trials |
Quick-reference tip: Jakafi targets JAK1/2—”JAK-afi” shrinks spleens in myelofibrosis and controls GVHD; watch blood counts closely.
Medical & AI Content Disclaimers
Medical Disclaimer: Medical definitions are provided for educational purposes and should not replace professional medical advice, diagnosis, or treatment.
AI Content Disclaimer: Some definitions may be AI-generated and may contain inaccuracies. Always verify with authoritative medical references.
