Gefitinib

Gefitinib tablets are indicated for the first-line treatment of patients with metastatic non-small cell lung cancer (NSCLC) whose tumors have epidermal growth factor receptor (EGFR) exon 19 deletions or exon 21 (L858R) substitution mutations as detected by an FDA-approved test . Limitation of Use: Safety and efficacy of gefitinib tablets have not been established in patients with metastatic NSCLC whose tumors have EGFR mutations other than exon 19 deletions or exon 21 (L858R) substitution mutations .

12.1 Mechanism of Action The epidermal growth factor receptor (EGFR) is expressed on the cell surface of both normal and cancer cells and plays a role in the processes of cell growth and proliferation. Some EGFR activating mutations (exon 19 deletion or exon 21 point mutation L858R) within NSCLC cells have been identified as contributing to the promotion of tumor cell growth, blocking of apoptosis, increasing the production of angiogenic factors and facilitating the processes of metastasis.

Systemic exposure to Gefitinib reflects ~60% systemic bioavailability (Gefitinib) absorption kinetics and gefitinib undergoes cyp3a4-mediated hepatic metabolism prior to excretion, sustaining receptor engagement across a Terminal t½ estimated at 7–20 hrs depending on renal/hepatic reserve (Gefitinib) half-life window (peak plasma tmax within 3-7 hours (gefitinib) response profile).

Dosing protocols (250 mg/1 Tablet, Film Coated or 250 mg/1 Tablet, Coated or 250mg Bottle of Tablets) balance efficacy (75.00% patient satisfaction across 7 logs) against nausea (8.8% of reports), diarrhea (8.5% of reports), headache (7.2% of reports), with strict avoidance in severe drug-induced hypersensitivity to gefitinib or inactive tablet/vehicle binders; prohibited co-prescriptions or physiological states specified in fda spl 2023-12-28 for gefitinib.