Imatinib mesylate
🚨 Urgent medical attention is required if the patient develops fever >38 °C, chills, breathlessness, or uncontrolled bleeding (nose, mouth, vagina, or rectum >15 min).
- Imatinib is a tyrosine kinase inhibitor (TKI), used primarily in chronic myeloid leukaemia (CML) and GIST.
- It revolutionised outcomes in CML by turning a previously fatal disease into a chronic, controllable condition.
⚙️ Mode of Action
- Selective inhibitor of tyrosine kinases (BCR-ABL, PDGFR, c-KIT).
- Blocks the BCR-ABL fusion protein produced by the Philadelphia chromosome → halts abnormal myeloid proliferation.
- Also inhibits c-KIT signalling in Gastrointestinal Stromal Tumours (GISTs).
🩺 Indications & Typical Dosage (verify with BNF)
- Chronic Myeloid Leukaemia (CML): Ph+ CML in chronic, accelerated, or blast phase; oral route (OD or BD depending on phase).
- Acute Lymphoblastic Leukaemia (ALL): For Ph+ relapsed/refractory cases (usually with chemotherapy).
- Myelodysplastic / Myeloproliferative Diseases (MDS/MPD): With PDGFR rearrangements.
- GIST: For unresectable, metastatic, or recurrent c-KIT positive GISTs.
- 💊 Usual dose: 400 mg OD PO (CML, GIST); up to 600–800 mg daily in advanced phases (split BD).
⚖️ Interactions
- Metabolised by CYP3A4 → interactions with inhibitors (ketoconazole, clarithromycin) and inducers (rifampicin, carbamazepine).
- May increase levels of warfarin, ciclosporin, and statins → monitor closely.
⚠️ Cautions
- Monitor FBC regularly → risk of cytopenias.
- Check U&E and LFTs during therapy.
- Use caution in hepatic or renal impairment.
- Pregnancy: teratogenic potential – avoid unless benefits outweigh risks.
⛔ Contraindications
- Severe hepatic impairment.
- Known hypersensitivity to imatinib or excipients.
❗ Side Effects
- 🩸 Haematological: pancytopenia, neutropenia, thrombocytopenia, anaemia.
- 🤢 GI: nausea, vomiting, diarrhoea, abdominal pain.
- 💧 Fluid retention: periorbital oedema, ankle swelling, pleural/pericardial effusions (rare).
- 💪 Musculoskeletal: cramps, myalgia, bone pain.
- 🩹 Dermatological: rash, pruritus.
- 🌡️ Constitutional: fever, fatigue.
