Understanding Lung Cancer Medications (cont.)
Tyrosine Kinase Inhibitors
Gefitinib (Iressa) and erlotinab (Tarceva) are members of a new class of anticancer drugs known as epidermal growth factor receptor tyrosine kinase (EGFR-TK) inhibitors. These drugs are used for advanced or metastatic (spread to other parts of the body) non-small cell lung cancer. They block signals within cancer cells that are needed for growth and survival.
A large clinical trial comparing gefitinib (Iressa) with placebo (sugar pills) showed no advantage in survival for non-small cell lung cancer. People currently taking gefitinib should consult with their doctor as soon as possible to determine if an alternative therapy is necessary. However, several groups of people, within the overall population studied, showed a positive response to gefitinib. The populations who responded well to gefitinib included Asians (particularly those of Japanese origin) and nonsmokers. Gefitinib was approved based on data from clinical trials showing tumor shrinkage in about 10% of people and improving symptoms in another 40% of people.
- Who should not use these medications: Individuals with an allergy to the drug or any of its components should not take this medication.
- Use: Tyrosine kinase inhibitors are administered as oral tablets.
- Gefitinib is taken orally as a tablet once each day with or without food.
- Erlotinab taken orally as a tablet once each day at least 1 hour before food or 2 hours after food.
- Drug or food interactions: Some other drugs, such as rifampin or phenytoin (Dilantin), may increase metabolism of gefitinib and erlotinab, thereby decreasing their effectiveness. Drugs that elevate stomach acid (Tagamet, Pepcid) may decrease gefitinib concentrations in the blood, thereby decreasing its effectiveness. Drugs such as ketoconazole (Nizoral), itraconazole (Sporanox), or clarithromycin (Biaxin) may decrease metabolism of gefitinib or erlotinab, thereby increasing the potential for side effects. Gefitinib and erlotinab may increase bleeding associated with warfarin (Coumadin) or other anticoagulants. A doctor or a pharmacist should be consulted before a person taking a tyrosine kinase inhibitor uses other drugs, including over-the-counter medications, vitamins, and herbal products.
- Side effects: A doctor will check a person’s blood at regular visits while that person is taking this drug.
- A doctor should be contacted immediately if any of the following side effects occur:
- Allergic reaction symptoms, including itching, hives, swelling of the face or hands, swelling or tingling in the mouth or throat, shortness of breath, and chest tightness
- Eye pain or difficulty seeing
- Severe, ongoing diarrhea, nausea, or vomiting
- Poor appetite
- Sudden or ongoing breathing problems, cough, or fever
- Sudden, severe stomach pain
- Elevated international normalized ratio (INR) results (INR measures the ability of the blood to form a clot; too high of an INR result is related to bleeding that is difficult to control.)
- Other side effects include the following:
- Dry skin
- Mild diarrhea, nausea, or vomiting
- Mild skin rash
Francisco Talavera, PharmD, PhD
Koyamangalath Krishnan, MD, FRCP
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