GEFITINIB
GEFITINIB  (ge-fi'ti-nib)  Iressa Classifications: antineoplastic agent; epidermal growth factor receptor (egfr); tyrosine kinase inhibitor (tki); Therapeutic:antineoplastic; egfr-tki Pregnancy Category: D |
Availability
250 mg tablets
Action
Gefitinib is a selective epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (EGFR-TKI). EGFR is expressed or overexpressed in many cancers. EGFR expression is associated with poor prognosis for cancer, development of metastasis, and resistance to chemotherapy, hormonal therapy, and radiation therapy.
Therapeutic Effect
Inhibits up-regulation or overexpression of EGRF in cancer cells, thus diminishing their capacity for cell proliferation, cell survival, and decreasing their invasive capacity and metastases.
Uses
Treatment of locally advanced or metastatic non-small cell lung cancer after failure of both platinum and docetaxel therapy in patients who have previously used gefitinib.
Unlabeled Uses
Treatment of head and neck and other solid tumors.
Contraindications
Hypersensitivity to gefitinib; pregnancy (category D), lactation; children <18 y.
Cautious Use
Severe renal impairment; hepatic impairment; bacterial/viral infection; dermatologic toxicities; GI disorders; hepatic insufficiency; interstitial lung disease (interstitial pneumonia, pneumonitis, and alveolitis), pulmonary fibrosis, respiratory insufficiency; myelosuppression; females of childbearing age; prior chemotherapy, radiation therapy; ocular toxicities (corneal ulcer, eye pain).
Route & Dosage
| Non-Small Cell Lung Cancer Adult: PO 250 mg q.d., may increase to 500 mg q.d. if on enzyme-inducing drugs Head and Neck Cancers Adult: PO 500 mg/d |
Administration
Oral- Give without regard to meals.
- Store tablets at 15°–30° C (59°–86° F).
Adverse Effects (≥1%)
Body as a Whole: Asthenia, peripheral edema. GI: Diarrhea, nausea, vomiting, anorexia, weight loss, stomatitis. Respiratory: Dyspnea, interstitial lung disease. Skin: Acne/acneiform rash, dry skin, pruritus, vesicular/bullous rash. Special Senses: Amblyopia, conjunctivitis, aberrant eyelash growth.Interactions
Drug: barbiturates, bosentan, carbamazepine, dexamethasone, nevirapine, oxcarbazepine, phenytoin or fosphenytoin, rifampin, rifabutin, rifapentine may increase metabolism and decrease levels of gefitinib; amiodarone, protease inhibitors, cimetidine, clarithromycin, dalfopristin; quinupristin, delavirdine, efavirenz, erythromycin, fluconazole, fluvoxamine, fluoxetine, imatinib, itraconazole, ketoconazole, mifepristone, nefazodone, and voriconazole may increase levels and toxicity of gefitinib; may increase INR with warfarin; h2-receptor antagonists, proton pump inhibitors may decrease absorption of gefitinib. Food: Grapefruit juice may increase levels and toxicity of gefitinib. Herbal: St. John's wort may decrease levels of gefitinib.Pharmacokinetics
Absorption: Slowly absorbed, 60% reaches systemic circulation. Peak: 3–7 h. Metabolism: In liver primarily by CYP3A4. Elimination: 86% in feces. Half-Life: 48 h.Nursing Implications
Assessment & Drug Effects
- Monitor pulmonary status and report promptly dyspnea, cough, and fever.
- Withhold drug and notify physician for significant elevations of transaminases, bilirubin, or alkaline phosphatase.
- Monitor for adverse effects, especially with concurrent use of drugs that may inhibit CYP3A4 (e.g., amiodarone, cimetidine, erythromycin, fluconazole, grapefruit juice, etc.). See INTERACTIONS.
- Lab tests: Periodic LFTs; frequent PT/INR with concurrent warfarin.
Patient & Family Education
- Report promptly any of the following: eye pain or irritation; fever; breathing difficulty or shortness of breath; mouth sores.
- Inform physician of all prescription, nonprescription, or herbal drugs you are taking.
- Females should use reliable contraceptives while taking this drug.
- Minimize or avoid intake of grapefruit juice while taking this drug.
Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; 
Canadian drug name; Prototype drug