Imatinib 1 A Pharma (Imatinib)

Imatinib is used in the treatment of malignancies driven by BCR‑ABL, c‑KIT or PDGFR signaling.

• Chronic myeloid leukemia (CML): reduces leukemic cell proliferation and improves survival.
• Gastrointestinal stromal tumor (GIST): inhibits tumor growth and delays disease progression.
• Philadelphia chromosome‑positive acute lymphoblastic leukemia (Ph+ ALL): contributes to remission induction.

• Imatinib selectively inhibits the BCR‑ABL tyrosine kinase as well as the related c‑KIT and platelet‑derived growth factor receptor (PDGFR) kinases. By blocking these intracellular signaling pathways, the drug prevents phosphorylation of downstream substrates, thereby halting uncontrolled cell division and inducing apoptosis in malignant cells that depend on these kinases for growth.

Imatinib may cause a range of adverse reactions, which are categorized by frequency and severity.

Common Side Effects

• Nausea and vomiting: mild to moderate gastrointestinal upset.
• Edema: peripheral swelling, often in the ankles.
• Muscle cramps or pain: especially in the lower limbs.
• Fatigue: generalized tiredness.
• Diarrhea: loose stools, usually self‑limited.
• Rash or skin irritation: mild erythema or pruritus.

Serious or Rare Side Effects

• Neutropenia or severe leukopenia: increased infection risk.
• Hepatotoxicity: elevated liver enzymes or hepatitis.
• Cardiac failure or reduced left‑ventricular ejection fraction.
• Severe bleeding events, especially when combined with anticoagulants.
• Pulmonary hypertension: shortness of breath and elevated pulmonary pressures.
• Stevens‑Johnson syndrome or toxic epidermal necrolysis: extensive skin detachment.

Before initiating therapy, clinicians should assess baseline health status and monitor patients regularly.

• Monitor blood counts: check complete blood count weekly during the first month.
• Assess liver function: perform baseline and periodic liver enzyme tests.
• Evaluate cardiac status: echocardiography for patients with pre‑existing heart disease.
• Avoid in patients with known hypersensitivity to imatinib or its excipients.
• Use caution during pregnancy and breastfeeding; discuss risks with a specialist.
• Store at below 25°C: keep in the original packaging, protect from moisture and direct sunlight.

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

Major Interactions (Avoid)

• Strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole): may raise imatinib levels and risk adverse effects.
• Strong CYP3A4 inducers (e.g., rifampicin, carbamazepine): can markedly reduce efficacy.
• Concomitant use with QT‑prolonging agents (e.g., sotalol, quinidine): may increase arrhythmia risk.

Moderate Interactions (Monitor Closely)

• CYP3A4 substrates with narrow therapeutic index (e.g., warfarin, tacrolimus): adjust dose based on INR or drug levels.
• Antacids containing aluminum or magnesium: may decrease absorption; separate administration by at least 2 hours.
• Vaccines (live attenuated): monitor immune response, as imatinib may blunt efficacy.