Imatinib Zentiva (Imatinib Mesilate)

Imatinib Zentiva is a tyrosine kinase inhibitor used in hematologic malignancies and selected solid tumours.

• Chronic myeloid leukemia (CML): controls disease by suppressing the BCR‑ABL driven leukemic clone.
• Philadelphia chromosome‑positive acute lymphoblastic leukemia (Ph+ ALL): contributes to remission by targeting the same fusion protein.
• Gastrointestinal stromal tumour (GIST): reduces tumour growth by inhibiting c‑KIT and PDGFR signalling.

• Imatinib Mesilate binds to the ATP‑binding pocket of BCR‑ABL, c‑KIT and PDGFR tyrosine kinases, stabilising them in an inactive conformation. This blocks downstream phosphorylation cascades that drive uncontrolled cell proliferation and survival, thereby limiting the expansion of malignant clones in affected tissues.

Common Side Effects

• Nausea: mild to moderate upset stomach.
• Edema: swelling of the extremities, especially ankles.
• Muscle cramps: occasional tightness or pain in muscles.
• Fatigue: general tiredness or lack of energy.
• Diarrhoea: loose stools occurring intermittently.
• Rash: mild skin irritation or redness.

Serious or Rare Side Effects

• Hepatotoxicity: elevated liver enzymes or liver injury.
• Severe neutropenia: markedly reduced white blood cell count increasing infection risk.
• Cardiac failure: signs of reduced heart function such as shortness of breath.
• Pulmonary hypertension: increased pressure in lung arteries causing breathlessness.
• Severe skin reactions: Stevens‑Johnson syndrome or toxic epidermal necrolysis.
• Tumour lysis syndrome: rapid tumour breakdown leading to metabolic disturbances.

Before starting therapy, patients should be evaluated for liver function, blood counts and cardiac status.

• Monitor liver enzymes: check hepatic function regularly during treatment.
• Assess blood counts: watch for neutropenia and thrombocytopenia.
• Evaluate cardiac function: baseline and periodic ECGs for patients with cardiac history.
• Review concomitant medications: avoid strong CYP3A4 inhibitors or inducers.
• Pregnancy and lactation: use only if potential benefit justifies risk; discuss with physician.
• Store at ambient temperature below 25°C: keep in the original pack, protect from moisture and light.

Imatinib Zentiva may interact with several drug classes, requiring careful management.

Major Interactions (Avoid)

• Strong CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin): may increase imatinib exposure and toxicity.
• Strong CYP3A4 inducers (e.g., rifampicin, carbamazepine): may reduce efficacy by lowering plasma levels.
• Antacids containing aluminium or magnesium: can impair absorption if taken simultaneously.

Moderate Interactions (Monitor Closely)

• CYP3A4 substrate drugs (e.g., midazolam, tacrolimus): dose adjustments may be needed.
• QT‑prolonging agents (e.g., sotalol, quinidine): monitor ECG for arrhythmia risk.
• Warfarin: monitor INR more frequently as imatinib can affect anticoagulation.