Imatinib Krka D.D. (Imatinib)

Imatinib acts on malignant cells driven by BCR‑ABL, c‑KIT or PDGFR signaling pathways.

• Chronic myeloid leukemia (CML): provides disease control by inhibiting BCR‑ABL‑driven proliferation.
• Philadelphia chromosome‑positive acute lymphoblastic leukemia (Ph+ ALL): induces remission through targeted kinase inhibition.
• Gastrointestinal stromal tumor (GIST): reduces tumor growth by blocking c‑KIT signaling.
• Other BCR‑ABL positive hematologic malignancies: offers therapeutic benefit where BCR‑ABL drives disease.

• Imatinib selectively binds to the ATP‑binding site of the BCR‑ABL tyrosine kinase, preventing phosphorylation of downstream substrates and halting uncontrolled cell division. It also inhibits the related c‑KIT and platelet‑derived growth factor receptor (PDGFR) kinases, disrupting signaling pathways essential for the survival and proliferation of certain cancer cells. This targeted inhibition restores normal cellular regulation in affected tissues.

Imatinib may cause a range of adverse reactions, varying from mild to severe.

Common Side Effects

• Nausea and vomiting: gastrointestinal discomfort occurring early in treatment.
• Edema: fluid retention, often in the lower extremities.
• Fatigue: persistent tiredness affecting daily activities.
• Muscle cramps: involuntary contractions, especially in the legs.

Serious or Rare Side Effects

• Hepatotoxicity: elevated liver enzymes or liver injury requiring monitoring.
• Cardiotoxicity: decreased left‑ventricular ejection fraction or heart failure.
• Severe neutropenia: marked reduction in neutrophil count increasing infection risk.
• Hypersensitivity reactions: rash, fever, or anaphylaxis in rare cases.

When prescribing Imatinib, clinicians should consider several safety measures and monitoring requirements.

• Monitor liver function: perform baseline and periodic hepatic enzyme tests.
• Assess cardiac status: evaluate ejection fraction before and during therapy.
• Check blood counts: regular CBC to detect neutropenia or anemia.
• Counsel on pregnancy risk: drug is contraindicated in pregnancy due to fetal toxicity.
• Avoid concomitant strong CYP3A4 inhibitors: may increase plasma levels.
• Store at ambient temperature: keep below 25 °C in original container, protect from moisture and light.

Imatinib interacts with several medicines that can alter its plasma concentration or increase toxicity.

Major Interactions (Avoid)

• Strong CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin): can raise Imatinib levels and risk serious toxicity.
• Potent CYP3A4 inducers (e.g., rifampicin, carbamazepine): may reduce efficacy by lowering drug exposure.

Moderate Interactions (Monitor Closely)

• Acid‑reducing agents (e.g., proton pump inhibitors, antacids): may decrease absorption; timing adjustments recommended.
• Anticoagulants (e.g., warfarin): Imatinib can enhance anticoagulant effect, requiring INR monitoring.
• Live attenuated vaccines: immunosuppression may affect response; consider deferral.