Home Drug Guide Imatinib Mesylate

Drug Guide

Generic Name

Imatinib Mesylate

Brand Names Gleevec, Imkeldi

Classification

Therapeutic: Antineoplastic agent

Pharmacological: Tyrosine kinase inhibitor

FDA Approved Indications

Chronic myeloid leukemia (CML)
Gastrointestinal stromal tumors (GIST)
Certain other malignancies such as Philadelphia chromosome-positive ALL and other rare malignancies

Mechanism of Action

Imatinib inhibits specific tyrosine kinases including BCR-ABL, c-KIT, and PDGF receptor tyrosine kinases, thereby blocking tumor cell proliferation and inducing apoptosis.

Dosage and Administration

Adult: Typically 400 mg once daily; dosage varies based on indication and response.

Pediatric: Dosing based on body surface area, usually 260 mg/m² daily for CML and GIST.

Geriatric: Adjustments based on renal and hepatic function; close monitoring recommended.

Renal Impairment: For mild to moderate impairment, no initial dose adjustment needed; severe impairment requires caution.

Hepatic Impairment: Use cautiously; dosage adjustments may be necessary based on hepatic function.

Pharmacokinetics

Absorption: Well absorbed orally, peak plasma levels in 1-4 hours.

Distribution: High protein binding (~95%), primarily to albumin.

Metabolism: Hepatic via CYP3A4, CYP3A5, and CYP2C8.

Excretion: Eliminated primarily in feces; small amounts in urine.

Half Life: Approximately 18 hours.

Contraindications

Hypersensitivity to imatinib or its components.

Precautions

Use with caution in patients with hepatic or renal impairment; monitor blood counts; risk of fluid retention, hepatotoxicity, and cardiac failure.

Adverse Reactions - Common

Edema (Common)
Nausea (Common)
Muscle cramps (Common)
Skin rash (Common)
Vomiting (Common)

Adverse Reactions - Serious

Myelosuppression (neutropenia, thrombocytopenia, anemia) (Serious)
Hepatotoxicity (Serious)
Heart failure, cardiomyopathy (Serious)
Severe skin reactions (Stevens-Johnson Syndrome, Toxic Epidermal Necrolysis) (Serious)

Drug-Drug Interactions

CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin), CYP3A4 inducers (e.g., rifampin), other QT prolonging agents.

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Monitor complete blood counts, liver function tests, and cardiac function. Assess for signs of fluid retention and skin reactions.

Diagnoses:

Risk for infection due to myelosuppression
Impaired skin integrity
Risk of bleeding

Implementation: Administer medication as prescribed; monitor for adverse effects; instruct patient to report signs of hepatotoxicity or cardiac symptoms.

Evaluation: Evaluate blood counts periodically, assess for adverse reactions, and ensure therapeutic response.

Patient/Family Teaching

Take medication exactly as prescribed, with or without food.
Report any symptoms of swelling, jaundice, rash, or cardiac symptoms.
Avoid pregnancy due to teratogenic effects; use effective contraception.
Inform about possible side effects and when to seek medical attention.

Special Considerations

Black Box Warnings:

Potential for severe hepatotoxicity, QT prolongation, and tumor lysis syndrome.

Genetic Factors: Genetic variations in CYP3A4 may affect drug metabolism.

Lab Test Interference: May cause elevations in liver enzymes, and interference with blood counts.

Overdose Management

Signs/Symptoms: Severe nausea, vomiting, diarrhea, hypotension, and hepatotoxicity.

Treatment: Supportive care, gastric lavage, activated charcoal, and monitoring in a medical facility.

Storage and Handling

Storage: Store at room temperature, 20°C to 25°C (68°F to 77°F).

Stability: Stable for the shelf life as per manufacturer instructions.