Before Using This Medicine

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For gefitinib, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to gefitinib.

Pregnancy—Tell your doctor if you are pregnant or if you intend to become pregnant. Studies in rats have shown that gefitinib causes miscarriages and deaths of the fetus.

Be sure that you have discussed this with your doctor before taking this medicine. It is best to use some kind of birth control while you are receiving gefitinib. Tell your doctor right away if you think you have become pregnant while receiving gefitinib.

Breast-feeding—It is not known whether gefitinib passes into the breast milk. However, gefitinib is not recommended during breast-feeding, because it may cause unwanted effects in nursing babies.

Children—Studies on this medicine have been done only in adult patients, and there is no specific information comparing use of gefitinib in children with use in other age groups.

Older adults—This medicine has been tested in elderly patients and has not been shown to cause different side effects or problems in older people than it does in younger adults.

Other medicines—Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking gefitinib, it is especially important that your doctor and pharmacist know if you are taking any of the following:

• CYP3A4 inducers such as
• Phenytoin (e.g., Dilantin), or
• Rifampin (e.g., Rifadin)—may decreases the effectiveness of gefitinib

• Histamine H₂ -receptor antagonist (medicine for ulcers), such as
• Cimetidine (e.g., Tagamet), or
• Ranitidine (e.g., Zantac )—may decrease the effectiveness of gefitinib

• Itraconazole (e.g., Sporanox) or
• Ketoconazole (e.g., Nizoral)—Higher blood levels of gefitinib may occur, increasing the chance of serious side effects

• Metoprolol (e.g., Toprol-XL, Lopressor)—Higher blood levels of metoprolol may occur

• Warfarin (e.g., Coumadin, Warfilone)—Bleeding may occur

Other medical problems—The presence of other medical problems may affect the use of gefitinib. Make sure you tell your doctor if you have any other medical problems, especially:

• Idiopathic pulmonary fibrosis—Condition may worsen while receiving gefitinib therapy

• Kidney disease or
• Liver disease—The chance of serious side effects is greatly increased