Gefinitib (Iressa®)

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About This Drug

Gefitinib is used to treat cancer. It is given orally (by mouth)

Possible Side Effects

  • Skin reactions such as rashes, dry skin, rash with fluid-filled bumps/blisters
  • Loose bowel movements (diarrhea)

Note: Each of the side effects above was reported in 20% or greater of patients treated with gefitinib. Not all possible side effects are included above.

Warnings and Precautions

  • Inflammation (swelling) of the lungs, which can be life-threatening; you may have a dry cough or trouble breathing.
  • Changes in your liver function, which can cause liver failure and be life-threatening
  • Severe loose bowel movements (diarrhea)
  • Perforation- a hole in your stomach, small and/or large intestine.
  • Blurred vision or other changes in eyesight
  • Severe allergic skin reactions. You may develop blisters on your skin that are filled with fluid or a severe red rash all over your body that may be painful. Skin can sometimes be weeping or peeling off.

Note: Some of the side effects above are very rare. If you have concerns and/or questions, please discuss them with your medical team.

How to Take Your Medication

  • You can take the medicine with or without food.
  • If you have difficulties swallowing tablets whole, you can dissolve tablets in 4 to 8 oz. of water and stir for 15 min, immediately drink the solution. Rinse the glass with 4 to 8 oz. and drink immediately.
  • If you take a proton pump inhibitor antacids such as (Protonix®, Nexium®, Prilosec®), take this drug at least 12 hours before or 12 hours after you take the antacid. If you take H2 receptor blocker antacids such as (Pepcid®, Tagamet®, and Zantac®), take this drug at least 6 hours before or 6 hours after you take the antacid.
  • Missed dose: If you miss a dose, take it as soon as you think about it, unless it is within 12 hours of your next dose, then skip the missed dose and go back to your normal schedule.Do not take 2 doses at the same time or extra doses.
  • If you vomit a dose, take your next dose at the regular time, and contact your physician. Do not take 2 doses at the same time and do not double up on the next dose.
  • Handling: Wash your hands after handling your medicine, your caretakers should not handle your medicine with bare hands and should wear latex gloves.
  • This drug may be present in the saliva, tears, sweat, urine, stool, vomit, semen, and vaginal secretions. Talk to your doctor and/or your nurse about the necessary precautions to take during this time.
  • Storage: Store this medicine in the original container at room temperature. Discuss with your nurse or your doctor how to dispose of unused medicine

Treating Side Effects

  • Drink plenty of fluids (a minimum of eight glasses per day is recommended).
  • If you have loose bowel movements, you should drink more fluids so that you do not become dehydrated (lack water in the body from losing too much fluid).
  • If you get diarrhea, eat low-fiber foods that are high in protein and calories and avoid foods that can irritate your digestive tracts or lead to cramping.
  • Ask your nurse or doctor about medicine that can lessen or stop your diarrhea.

Food and Drug Interactions

  • Do not eat grapefruit or drink grapefruit juice while taking this medicine.Grapefruit and grapefruit juice may raise the levels of gefitinib in your body. This could make side effects worse.
  • Avoid the use of St. John’s Wort while taking gefitinib as this may lower the levels of the drug in your body, which can make it less effective.
  • Check with your doctor or pharmacist about all other prescription or over-the-counter medicines and dietary supplements (vitamins, minerals, herbs or others) you are taking before starting this medicine as there are known drug interactions with gefinitib. Also, check with your doctor or pharmacist before starting any new prescription, over-the-counter medicines, or dietary supplements to make sure that there are no interactions.
  • There are known interactions of gefinitib with blood-thinning medicine such as warfarin. Ask your doctor what precautions you should take.
  • Drugs that treat heartburn and stomach upset suchProtonix®, Nexium®, Prilosec®, Pepcid®, Tagamet®, and Zantac® may lower the effect of your cancer treatment if taken with gefitnib. Follow the instructions in the How to Take Your Medication section, or talk to your doctor.

When to Call the Doctor

Call your doctor or nurse if you have any of these symptoms and/or any new or unusual symptoms:

  • Fever of 100.5 F (38 C) or higher
  • Chills
  • Blurred vision or other changes in eyesight
  • Sensitivity to light
  • Pain in your chest
  • Dry cough
  • Trouble breathing
  • Severe abdominal pain that does not go away
  • Nausea that stops you from eating or drinking and/or is not relieved by prescribed medicine
  • Throwing up more than 3 times a day
  • Loose bowel movements (diarrhea) 4 times a day or loose bowel movements with lack of strength or a feeling of being dizzy
  • Flu-like symptoms: fever, headache, muscle and joint aches, and fatigue (low energy, feeling weak)
  • A new rash or a rash that is not relieved by prescribed medicines
  • Signs of possible liver problems: dark urine, pale bowel movements, bad stomach pain, feeling very tired and weak, unusual itching, or yellowing of the eyes or skin
  • If you think you may be pregnant

Reproduction Warnings

  • Pregnancy warning: This drug can have harmful effects on the unborn baby. Women of childbearing potential should use effective methods of birth control during your cancer treatment and for at least 2 weeks after treatment. Let your doctor know right away if you think you may be pregnant.
  • Breastfeeding warning: Women should not breast feed during treatment because this drug could enter the breast milk and cause harm to a breastfeeding baby.
  • Fertility warning: In women, this drug may affect your ability to have children in the future. Talk with your doctor or nurse if you plan to have children. Ask for information on egg banking.

Revised February 2018

This information is intended to provide helpful health information to the general public and is not to be used in place of any medical, health, psychological, or any other kind of personal professional services. The information herein does not cover all possible uses, actions, precautions, side effects, or interactions of the medicines mentioned, nor is the information intended as medical advice for individual problems or for making an evaluation as to the risks and benefits of taking a particular medication. The dose, method of administration and contraindications for any administered medication should be confirmed before use. UPMC specifically disclaims all responsibility for any liability, loss or risk, personal or otherwise, which is incurred as a consequence, directly or indirectly, of the use and application of any medication mentioned herein.