Imatinib

Imatinib is used to target specific tyrosine‑kinase driven malignancies.

• Chronic myeloid leukemia: reduces leukemic cell proliferation and achieves durable hematologic and cytogenetic responses.
• Philadelphia chromosome‑positive acute lymphoblastic leukemia: induces remission by inhibiting BCR‑ABL signaling in leukemic blasts.
• Gastrointestinal stromal tumor: controls tumor growth by blocking c‑KIT and PDGFR pathways.

• Imatinib selectively inhibits the BCR‑ABL tyrosine kinase produced by the Philadelphia chromosome translocation, as well as the related receptors c‑KIT and platelet‑derived growth factor receptor (PDGFR). By binding to the ATP‑binding site of these kinases, it prevents phosphorylation of downstream substrates, thereby blocking abnormal cell proliferation and inducing apoptosis in malignant cells.

Imatinib may cause a range of adverse reactions, varying in frequency and severity.

Common Side Effects

• Nausea: mild to moderate gastrointestinal upset.
• Edema: peripheral swelling, often in the hands or feet.
• Fatigue: general tiredness affecting daily activities.
• Diarrhea: loose stools, sometimes accompanied by abdominal cramping.
• Muscle cramps: involuntary tightening of skeletal muscles.
• Rash: mild skin erythema or itching.

Serious or Rare Side Effects

• Hepatotoxicity: elevated liver enzymes or liver injury.
• Cardiotoxicity: decreased left ventricular ejection fraction or heart failure.
• Severe neutropenia: marked reduction in neutrophil count increasing infection risk.
• Pulmonary hypertension: elevated pressure in lung arteries causing breathlessness.
• Hemorrhagic events: bleeding complications, including gastrointestinal bleeding.
• Anaphylaxis: rare systemic allergic reaction requiring immediate medical attention.

When prescribing Imatinib, clinicians should consider several precautionary measures to ensure patient safety.

• 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 monitoring for neutropenia or anemia.
• Evaluate drug interactions: review concomitant medications that affect CYP3A4.
• Counsel on pregnancy: avoid use during pregnancy unless benefits outweigh risks.
• Store at ambient temperature: keep below 25 °C in original packaging, protect from moisture and light.

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

Major Interactions (Avoid)

• Strong CYP3A4 inducers (e.g., rifampin, carbamazepine): may markedly reduce Imatinib exposure.
• Strong CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin): can increase Imatinib levels and risk of adverse effects.
• Antacids containing aluminum or magnesium: may decrease absorption if taken simultaneously.

Moderate Interactions (Monitor Closely)

• Proton pump inhibitors: may modestly affect gastric pH and drug uptake.
• Warfarin: potential for altered anticoagulant effect, requiring INR monitoring.
• Live attenuated vaccines: possible reduced efficacy; assess timing relative to therapy.