Ruxolitinib (generic brand: Apotex)
(also sold under the brand name Jakafi™ by other manufacturers)
What is it?
- Class: Oral Janus‑kinase (JAK) 1/2 inhibitor
- Mechanism: Blocks JAK‑1 and JAK‑2 signaling pathways that drive abnormal growth of blood cells.
- Uses (as approved in most countries):
- Primary or secondary myelofibrosis (a bone‑marrow disorder)
- Polycythemia vera (an over‑production of red blood cells) that is resistant or intolerant to hydroxyurea
Typical dosing (myelofibrosis example)
| Condition |
Starting dose |
Titration |
Maintenance |
Frequency |
| Myelofibrosis |
5 mg PO BID |
↑ 5 mg every 4 days if tolerated |
10–25 mg PO BID (max 25 mg BID) |
Twice daily |
| Polycythemia vera |
Same as myelofibrosis |
Same |
Same |
Twice daily |
Note: The actual dose depends on platelet count, anemia, age, weight, and other individual factors. Always follow your prescriber’s instructions.
Common side effects
- Blood‑related: anemia, thrombocytopenia, neutropenia
- Infection risk: ↑ risk of bacterial, fungal, and viral (including reactivation of herpes zoster) infections
- GI: nausea, diarrhea, vomiting, abdominal pain
- Others: fatigue, headache, dizziness, elevated liver enzymes, rash
Severe or life‑threatening reactions:
- Serious infections (e.g., sepsis)
- Severe anemia or thrombocytopenia (requiring transfusion)
- Liver injury (persistent elevation of AST/ALT >5× ULN)
Patients on ruxolitinib are usually monitored with regular CBCs (at least every 2–4 weeks in the first 3 months, then every 4–12 weeks thereafter) and liver function tests.
Drug interactions
| Drug/Agent |
Effect on Ruxolitinib |
Why |
| CYP3A4 inhibitors (e.g., clarithromycin, ketoconazole, itraconazole, ritonavir) |
↑ Ruxolitinib levels |
Ruxolitinib is metabolized by CYP3A4 |
| CYP3A4 inducers (e.g., rifampin, carbamazepine, phenytoin, St. John’s wort) |
↓ Ruxolitinib levels |
↑ metabolism |
| Other JAK inhibitors, immunosuppressants (e.g., methotrexate, cyclosporine) |
↑ immunosuppression |
Additive effect |
| Anticoagulants |
Possible ↑ bleeding risk |
Ruxolitinib can affect platelet function |
Tip: Always inform your pharmacist about all medications, supplements, and over‑the‑counter drugs you’re taking.
Precautions & Contraindications
- Pregnancy & Lactation: Category D. Use only if the benefit outweighs the risk; avoid during pregnancy and breastfeeding unless no alternatives exist.
- Active infections: Avoid initiating therapy in untreated infections (especially tuberculosis, hepatitis B/C).
- History of severe bleeding or thrombosis: May increase risk.
- Hepatic impairment: Dose adjustment or careful monitoring may be needed.
- Renal impairment: Generally safe, but close monitoring if severe.
Storage & Handling
- Storage temperature: 20–25 °C (68–77 °F).
- Keep out of reach of children – the tablets may cause serious harm if ingested.
- Do not freeze or expose to excessive heat.
What to do if you miss a dose?
- Take the missed dose as soon as you remember unless it’s almost time for the next dose.
- Do not double‑dose.
Bottom line
Ruxolitinib (including the Apotex generic) is a powerful medication that can significantly improve symptoms and reduce spleen size in myelofibrosis and control blood counts in polycythemia vera. However, its immunosuppressive effects and potential for serious blood‑count changes require close medical supervision, regular lab monitoring, and vigilance for infections or bleeding.
If you have any specific questions about your own treatment, side‑effect concerns, or drug interactions, please contact your prescribing physician or pharmacist.