Uses

Gefitinib is an EGFR tyrosine kinase inhibitor indicated as first-line treatment of adults with metastatic non-small cell lung cancer (NSCLC) whose tumors harbor EGFR exon 19 deletions or exon 21 (L858R) substitution mutations as detected by an FDA-approved test.

Do not use if

No absolute contraindications listed in the FDA label. Use with caution in patients with hepatic impairment. Concomitant strong CYP3A4 inducers (e.g., rifampin, phenytoin) significantly reduce gefitinib exposure.

Side effects

Common adverse effects include diarrhea, skin rash, acne, dry skin, nausea, and elevated liver enzymes. Serious risks include interstitial lung disease, hepatotoxicity, gastrointestinal perforation, severe persistent diarrhea, and ocular disorders.

Warnings

Withhold gefitinib for worsening respiratory symptoms and discontinue permanently if ILD is confirmed. Monitor liver function periodically. Use effective contraception in women of childbearing potential; drug is embryo-fetal toxic.

How it works

Gefitinib reversibly inhibits the EGFR tyrosine kinase by competing with ATP at the kinase domain, preferentially targeting activating mutations (exon 19 deletions and L858R) that drive tumor proliferation in NSCLC. This leads to reduced downstream signaling via MAPK and PI3K/AKT pathways.

Storage

Store at room temperature below 30°C, away from moisture and light.