- What is gefitinib, and how does it work (mechanism of action)?
- What brand names are available for gefitinib?
- Is gefitinib available as a generic drug?
- Do I need a prescription for gefitinib?
- What are the side effects of gefitinib?
- What is the dosage for gefitinib?
- Which drugs or supplements interact with gefitinib?
- Is gefitinib safe to take if I'm pregnant or breastfeeding?
- What else should I know about gefitinib?
What is gefitinib, and how does it work (mechanism of action)?
Gefitinib is a drug that is used to treat several types of lung cancer. It works by preventing lung cancer cells from growing and multiplying. Many cells, including cancer cells, have receptors on their surfaces for epidermal growth factor (EGF), a protein that is normally produced by the body and that promotes the growth and multiplication of cells. When EGF attaches to epidermal growth factor receptors (EGFRs), it causes an enzyme called tyrosine kinase to become active within the cells. Tyrosine kinase triggers chemical processes that cause the cells, including cancer cells, to grow, multiply, and spread. Gefitinib attaches to EGFRs and thereby blocks the attachment of EGF and the activation of tyrosine kinase. This mechanism for stopping cancer cells from growing and multiplying is very different from the mechanisms of chemotherapy and hormonal therapy. Gefitinib was approved by the FDA in May 2003.
What are the side effects of gefitinib?
About one in one hundred persons receiving gefitinib develop a potentially serious lung condition called interstitial lung disease that causes inflammation within the lung. Therefore, patients taking gefitinib who develop new or worsening cough, fever, or difficulty in breathing should contact their physician immediately.
Eye irritation has been observed in patients receiving gefitinib, and patients who develop the onset of new eye symptoms should contact their physician.
All patients taking gefitinib should seek medical advice promptly if they develop severe or persistent
What is the dosage for gefitinib?
Gefitinib is taken by mouth. The dose is 250 mg once daily. The dose is the same for men or women of any age or weight, and gefitinib can be taken with or without food.
Which drugs or supplements interact with gefitinib?
Gefitinib may increase the blood-thinning effects of warfarin (Coumadin) and increase the risk of bleeding. Therefore, patients receiving gefitinib and warfarin at the same time should have more frequent testing of the "thinness" of their blood.
Patients who receive drugs that increase an enzyme in the liver called CYP 3A4 that destroys gefitinib (for example, rifampin or phenytoin (Dilantin) may need a higher dose of gefitinib to maintain the effectiveness of gefitinib.
Similarly, patients who receive drugs that reduce CYP 3A4, for example, ketoconazole (Nizoral), itraconazole (Sporanox), fluconazole (Diflucan), erythromycin, clarithromycin (Biaxin), ritonavir (Norvir), nelfinavir (Viracept), indinavir (Crixivan), nefazodone (Serzone), as well as grapefruit juice, may need a lower dose of gefitinib to prevent side effects from increased levels of gefitinib.
Is gefitinib safe to take if I'm pregnant or breastfeeding?
Gefitinib should not be used by pregnant women.
It is not known whether gefitinib is secreted in human milk. Since there is a possibility of toxicity in nursing infants, it is recommended that breastfeeding be stopped if the mother is treated with gefitinib.
gefitinib (Iressa Discontinued in the US) is a drug prescribed for the treatment of certain types of lung cancer. Side effects, drug interactions, and warnings and precautions should be reviewed prior to taking this medication.
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