Iressa

Iressa,

a trademark for gefitinib.

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gefitinib Warning - High-alert drug!

Iressa

Pharmacologic class: Epidermal growth factor receptor inhibitor

Therapeutic class: Antineoplastic

Pregnancy risk category D

Action

Unclear. Inhibits tyrosine kinase action, which inhibits cell growth and reproduction. May also inhibit angiogenesis in tumor cells.

Availability

Tablets: 250 mg

⊘Indications and dosages

➣ Locally advanced or metastatic non-small-cell lung cancer after failure of platinum-based and docetaxel chemotherapy

Adults: 250 mg P.O. daily

Dosage adjustment

• Patients with diarrhea or skin reactions, pulmonary symptoms, or ocular symptoms
• Patients taking CYP3A4 inducers concurrently

Contraindications

• Severe hypersensitivity to drug or its components

Precautions

Use cautiously in:
• hepatic impairment or hepatotoxicity
• pregnant or breastfeeding patients
• children.

Administration

• Give with or without food.

Route	Onset	Peak	Duration
P.O.	Unknown	3-7 hr	Unknown

Adverse reactions

CNS: asthenia

EENT: amblyopia, conjunctivitis, eye pain and corneal ulcer

GI: diarrhea, nausea, vomiting, mouth ulcers, anorexia

Respiratory: dyspnea, interstitial lung disease

Skin: acne, rash, dry skin, pruritus, vesiculobullous rash

Other: peripheral edema, weight loss

Interactions

Drug-drug. Histamine₂-receptor antagonists (such as cimetidine, ranitidine), phenytoin, rifampin: decreased gefitinib blood level

Itraconazole, ketoconazole: increased gefitinib blood level

Metoprolol: increased metoprolol exposure

Warfarin: increased International Normalized Ratio (INR), increased bleeding events

Drug-diagnostic tests. Alkaline phosphatase, bilirubin, hepatic enzymes: increased levels

Patient monitoring

• Monitor INR and watch for signs and symptoms of bleeding if patient is also receiving warfarin.
• Monitor liver function test results.
☞ Watch for dehydration if patient has severe or persistent diarrhea, anorexia, nausea, or vomiting.
☞ If patient experiences worsening pulmonary symptoms, severe diarrhea, skin reactions, or ocular symptoms, expect to stop therapy until cause is determined or problems resolve.
☞ Discontinue therapy if interstitial lung disease is confirmed.

Patient teaching

• Tell patient to take with or without food.
☞ Instruct patient to immediately report severe or persistent diarrhea, anorexia, nausea, vomiting, increased shortness of breath or cough, eye irritation, or new symptoms.
• Caution female of childbearing age not to become pregnant.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs and tests mentioned above.