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Side Effects of Gefitinib (Iressa)


Side Effects of Gefitinib (Iressa)

Gefitinib, available under the brand Iressa is in a class of anticancer drugs called tyrosine kinase inhibitors. This cancer medication interferes with the growth of cancer cells and is used to treat non-small cell lung cancer. Iressa is sometimes used for cancers in other parts of the body.


Iressa is a signal transduction inhibitor, a special case of what’s called targeted therapy in cancer. Targeted therapy, as the name suggest, targets specific molecules that are involved in growth of cancer cells. Iressa is a specific inhibitor of the epidermal growth factor portion of the tyrosine kinase domain. The target protein (EGFR) is a family of receptors that includes the Her1(erb-B1), Her2(erb-B2), and Her3(erb-B3). The drug interrupts signaling in target cells, thereby reducing cancer cell growth in cells that have mutated and overactive EGFR.


Iressa was used as a third line therapy after both platinum-based and docetaxel chemotherapies failed. It was withdrawn from the market for new patients in 2005 after the FDA determined the lack of evidence that it extended life. It is currently marketed in a number of European countries.

Warnings Before Taking Iressa

Before taking Iressa inform your doctor if you have liver disease, vision problems, kidney disease, breathing problems, lung disease or if you take a blood thinner.

Iressa Side Effects

The FDA reports Gefitinib has a tolerability profile better than previous cytotoxic agents as it is a selective chemotherapeutic agent.


Adverse drug reactions are considered acceptable for a potentially fatal disease. They include:


  • Acne-like rash
  • Diarrhea
  • Nausea and vomiting
  • Anorexia
  • Dehydration
  • Stomatitis (inflammation of the mucous membrane of the mouth)
  • Skin reactions
  • Increase in liver enzymes
  • Paronychia (nail disease or infection)
  • Asthenia (abnormal physical weakness)
  • Conjunctivitis (pink eye)
  • Blepharitis (inflammation of the eyelid)

About Pharmacogenetic Testing

Pharmacogenetics grew out of the sequencing of the human genome and is an important medical field. Genome wide association studies conducted by researchers showed that variation in the genes are responsible for metabolizing drugs. That means that it’s possible you have variations in your own drug metabolism genes. Practically, this may mean that there are some drugs that you cannot metabolize well, or that you may metabolize some drugs too quickly. In each case your dose would be changed from the recommended dose. In some cases the test results may inform your physician that some drugs are not safe for you and you would be prescribed a different drug.

Know Your Risk with the Rxight® Genetic Test

The Rxight® pharmacogenetics test from MD Labs tests most of your genes involved in drug metabolism from one cheek swab. This amazing advance in personalized medicine is now available to you, with a participating pharmacy. It tests your ability to metabolize over 200 drugs and over-the-counter (OTC) medications in one test, and could change the way you respond to many newly prescribed medications.


Call us to learn more about Rxight® pharmacogenetic testing, at 1-888-888-1932 or email us at support@Rxight.com.


Contributors to this Article:
Michael Sapko, MD, PhD; and Deborah Kallick, PhD, Medicinal Chemistry

Read more about Rxight® : What is Pharmacogenetics?