- 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 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.
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