Other Brands/Names

Gefitero, Iressa.

How It Works

Gefitinib is an anticancer agent to treat certain lung cancers and belongs to the drug class of tyrosine kinase inhibitor. Gefitinib works by specifically blocking the tyrosine kinase enzyme. This enzym is found specifically on the surface of cancer cells.

Additionally, gefitinib also suppresses the signaling activity through the Epidermal Growth Factor Receptor (EGFR). Some types of lung cancers carry EGFR mutations. Because EGFR drives the growth and spread of cancer cells, blocking this pathway can slow the growth and spread of lung cancer cells.

For this reason, gefitinib is only effective in treating lung cancer cells that harbor EGFR mutations.

Indications

• Localized non-small cell lung cancer or metastatic lung cancer in patients with EGFR mutations.

• Advanced non-small cell lung cancer, both localized or cancer that has metastasized, after prior treatments have failed or when previous chemotherapy is not tolerated by patients.

Contraindication

Do not use gefitinib if the patient:

• Has hypersensitivity or allergic reaction to this medicine.

• Is breastfeeding.

Side Effects

The most frequent adverse effects are diarrhea and skin reactions such as rash, acne, dry skin, and itchiness.

Side effects typically appear within the first month of therapy and are usually reversible. Other commonly reported effects include:

• Decreased appetite

• Nausea

• Vomiting

• Elevated liver enzyme levels

This medicine may also cause side effects of asthenia, a sensation of weakness and fatigue. People who experience this should be cautious when driving or operating machinery.

Types

250 mg tablets.

Dosage

The dosage of gefitinib for adults is 250 mg once daily. The treatment should be stopped if the disease progresses or adverse effects cannot be tolerated by patients.

Safety

The safety of gefitinib in pregnant women is unknown, but data from animal studies indicate there is potential harm to fetus. Gefitinib has also been detected in the milk of lactating animals in studies. Therefore, gefitinib should not be given to breastfeeding mothers.

Drug Interactions

• Blood levels and efficacy of gefitinib may decrease when this medicine is used with:
  

  • Rifampinin (antituberculosis)

  • Phenytoin (anticonvulsant medicine)

  • Antacids and proton pump inhibitors, such as omeprazole and ranitidine

• Gefitinib levels and effects may increase if it interacts with CYP3A4 inhibitors, such as:

  • The antifungal ketoconazole

  • The antibiotic clarithromycin

• Concomitant use of gefitinib with the blood thinner warfarin may increase the risks of bleeding.
• Combined use of gefitinib with NSAIDs or steroids may increase the risk of gastrointestinal leakage.

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