Gefitinib

Introduction: Gefitinib is used in the treatment of non-small cell lung cancer. It is used in patients in which it has spread to other parts of the body, who have abnormal epidermal growth factor receptor (EGFR) genes, and who have not had previous treatment for cancer.

How it works: Gefitinib is an anti-cancer medication. It works by blocking the action of the abnormal protein that signals cancer cells to multiply. This helps to stop or slow the spread of cancer cells.

Important Information: Continue treatment as advised by your doctor. Do not take antacids 2 hours before or 1 hour after taking this medicine. Avoid during pregnancy and lactation.

• Metastatic non-small cell lung cancer (NSCLC): with EGFR exon 19 deletions or exon 21 (L858R) substitution mutations

Targeted Cancer Therapy

EGFR Tyrosine Kinase Inhibitor

Gefitinib reversibly inhibits the kinase activity of wild-type and certain activating mutations of EGFR, preventing autophosphorylation of tyrosine residues associated with the receptor, thereby inhibiting further downstream signalling and blocking EGFR-dependent proliferation. Gefitinib binding affinity for EGFR exon 19 deletion or exon 21 point mutation L858R mutations is higher than its affinity for the wild-type EGFR.

Gefitinib inhibits EGFR tyrosine kinase enzyme to prevent cancer cell growth and proliferation.

Adult Dose:

• 250 mg once daily with or without food
• Continue until disease progression or unacceptable toxicity
• Do not take a missed dose within 12 hours of the next dose

Difficulty Swallowing Solids:

• Immerse tablet in 4-8 ounces of water
• Stir for approximately 15 minutes
• Drink liquid immediately or administer through naso-gastric tube

* Use as directed by the registered physician

Oral tablet. Can be taken with or without food. Swallow whole, do not chew or crush. Take antacids 2 hours before or 1 hour after taking this medicine.

If you miss a dose, skip it and continue with your normal schedule. Do not double the dose.

Common Side Effects:

• Diarrhea
• Dry skin
• Loss of appetite
• Nausea
• Rash
• Stomatitis
• Vomiting
• Weakness

Serious Side Effects: Interstitial Lung Disease, Hepatotoxicity, Gastrointestinal Perforation, Severe Diarrhea, Keratitis, Bullous and Exfoliative Skin Disorders.

Precautions:

• Interstitial Lung Disease (ILD): Withhold and investigate if respiratory symptoms worsen.
• Hepatotoxicity: Regular liver function testing. Discontinue in severe hepatic impairment.
• Gastrointestinal Perforation: Permanently discontinue if occurs.
• Severe Diarrhea: Withhold for severe or persistent diarrhea.
• Avoid during pregnancy and lactation.

Contraindications:

• Hypersensitivity to Gefitinib or any components

Drug Interactions:

• CYP3A4 Inducers (rifampicin, phenytoin, carbamazepine): Decrease gefitinib plasma concentrations (increase dose to 500 mg).
• CYP3A4 Inhibitors (ketoconazole, itraconazole): Increase gefitinib plasma concentrations.

Food Interactions:

• Unsafe to consume alcohol with Gefitinib.

Use in Pregnancy: Unsafe during pregnancy. There is definite evidence of risk to the developing baby.

Use in Lactation: Probably unsafe during breastfeeding. Limited data suggests the drug may pass into breastmilk and harm the baby.

Pediatric Use: Safety and effectiveness in pediatric patients have not been established.

Geriatric Use: No specific dosage adjustment is necessary for elderly patients.

Renal Impairment: Use with caution in severe kidney disease. Dose adjustment may be needed.

Hepatic Impairment: Monitor for adverse reactions in moderate and severe hepatic impairment.

Overdose: Overdose may cause myelosuppression, paresthesias and severe rash. Appropriate blood counts and supportive therapy.

Storage: Store between 20-25°C in a cool and dry place, away from sunlight. Keep out of reach of children.

Gefitinib Tablet