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gefitinib (Oral route)


Commonly used brand name(s)

In the U.S.

  • Iressa

Available Dosage Forms:

  • Tablet

Therapeutic Class: Antineoplastic Agent

Pharmacologic Class: Tyrosine Kinase Inhibitor

Uses For gefitinib

Gefitinib is used to treat metastatic (cancer that has already spread) non-small cell lung cancer in patients who have certain types of abnormal epidermal growth factor (EGFR) genes, and did not receive cancer medicines in the past. Your doctor will perform a test before you take gefitinib.

Gefitinib belongs to the group of medicines called antineoplastics (cancer medicines). It works by interfering with the growth of cancer cells, which are eventually destroyed.

gefitinib is available only with your doctor's prescription.

Before Using gefitinib

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:


Tell your doctor if you have ever had any unusual or allergic reaction to gefitinib or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.


Appropriate studies have not been performed on the relationship of age to the effects of gefitinib in the pediatric population. Safety and efficacy have not been established.


Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of gefitinib in the elderly.

Breast Feeding

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Interactions with 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 healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using gefitinib with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Dasabuvir
  • Ombitasvir
  • Paritaprevir
  • Topotecan
  • Vinorelbine

Using gefitinib with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Fosphenytoin
  • Itraconazole
  • Ketoconazole
  • Phenytoin
  • Ranitidine
  • Rifampin
  • Warfarin

Interactions with Food/Tobacco/Alcohol

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

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:

  • Diarrhea or
  • Eye or vision problems (eg, conjunctivitis, corneal erosion, keratitis) or
  • Lung or breathing problems (eg, interstitial lung disease), history of or
  • Stomach or bowel problems (eg, gastrointestinal perforation)—Use with caution. May make these conditions worse.
  • Liver disease—Use with caution. The effects may be increased because of slower removal from the body.

Proper Use of gefitinib

Medicines used to treat cancer are very strong and can have many side effects. Before using gefitinib, make sure you understand all the risks and benefits. It is important for you to work closely with your doctor during your treatment.

gefitinib should come with a patient information insert. Read and follow these instructions carefully. Ask your doctor if you have any questions.

You may take gefitinib with or without food.

If you have trouble swallowing the tablets:

  • Dissolve the tablet in 4 to 8 ounces of water.
  • Stir the mixture for approximately 15 minutes.
  • Drink the liquid immediately or it may be given through a nasogastric tube.
  • Add 4 to 8 ounces of water in the same container, and drink it immediately.

If you take a stomach medicine for heartburn or ulcers (such as cimetidine, famotidine, ranitidine, Pepcid®, Tagamet®, Zantac®), take the heartburn medicine at least 6 hours before or 6 hours after you take gefitinib.

If you take a stomach medicine (such as dexlansoprazole, lansoprazole, omeprazole, pantoprazole, Aciphex®, Dexilant®, Nexium®, Prevacid®, Prilosec®), take these medicines at least 12 hours before or 12 hours after you take gefitinib. It is best to avoid these medicines unless your doctor tells you otherwise.


The dose of gefitinib will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of gefitinib. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For oral dosage form (tablets):
    • For lung cancer:
      • Adult—250 milligrams (mg) once a day.
      • Children—Use and dose must be determined by your doctor.

Missed Dose

If you miss a dose of gefitinib, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Do not take gefitinib if it has been more than 12 hours since you missed your last dose.


Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

Precautions While Using gefitinib

It is very important that your doctor check your progress at regular visits to make sure gefitinib is working properly. Blood tests may be needed to check for unwanted effects.

Using gefitinib while you are pregnant can harm your unborn baby. Use an effective form of birth control to keep from getting pregnant. You should continue to use birth control for at least 14 days after your last dose. If you think you have become pregnant while using the medicine, tell your doctor right away.

If you plan to have children, talk with your doctor before using gefitinib. Some women using gefitinib have become infertile (unable to have children).

Call your doctor right away if you have unexplained shortness of breath, cough, and fever that comes on suddenly. These could be symptoms of a serious lung condition.

Check with your doctor right away if you have dark urine or pale stools, yellow skin or eyes, nausea or vomiting, or upper stomach pain. These could be symptoms of a liver problem.

Check with your doctor right away if you have bloody or black, tarry stools, severe stomach pain, or vomiting of blood or material that looks like coffee grounds. These could be symptoms of a serious stomach or bowel problem.

It is important that you talk to your doctor right away if you have severe or continuing diarrhea that lasts up to 14 days.

Check with your doctor right away if blurred vision or any vision change, eye pain, or eye irritation occurs during or after treatment. Your doctor may want you to have your eyes checked by an ophthalmologist (eye doctor).

Serious skin reactions can occur with gefitinib. Check with your doctor right away if you have blistering, peeling, or loosening of the skin, red skin lesions, severe acne or skin rash, sores or ulcers on the skin, or fever or chills while you are using gefitinib.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal (St. John's wort) or vitamin supplements.

gefitinib Side Effects

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

More common
  • Abdominal or stomach pain or tenderness
  • clay colored stools
  • dark urine
  • decreased appetite
  • diarrhea, severe
  • fever
  • headache
  • itching or skin rash
  • loss of appetite
  • nausea and vomiting
  • swelling of the feet or lower legs
  • unusual tiredness or weakness
  • yellow eyes or skin
Less common
  • Burning, dry, or itching eyes
  • chest pain
  • chills
  • cough
  • difficult breathing
  • discharge or excessive tearing
  • dry eyes
  • general feeling of discomfort or illness
  • redness, pain, or swelling of the eye, eyelid, or inner lining of the eyelid
  • thickening of bronchial secretions
  • troubled breathing
  • troubled or quick, shallow breathing
  • Blistering, peeling, or loosening of the skin
  • bloody, black, or tarry stools
  • eye redness, irritation, or pain
  • heartburn
  • indigestion
  • joint or muscle pain
  • red skin lesions, often with a purple center
  • severe abdominal or stomach pain, cramping, or burning
  • sore throat
  • sores, ulcers, or white spots in the mouth or on the lips
  • vomiting of material that looks like coffee grounds, severe and continuing

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Less common
  • Redness or soreness around fingernails or loosening of the fingernails

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

See also: Side effects (in more detail)

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