How does it work?

Iressa tablets contain the active ingredient gefitinib, which is a type of medicine known as a protein kinase inhibitor. It works by interfering with the pathways that signal certain cancer cells to grow.

Many cancer cells have structures called epidermal growth factor receptors (EGFRs) on their surfaces. These receptors allow a protein called epidermal growth factor (EGF) to attach to the cells. When the epidermal growth factor attaches to the receptor, it activates an enzyme in the cell called tyrosine kinase. This enzyme triggers chemical processes inside the cancer cells that make the cells grow and multiply.

Gefitinib works by attaching to and blocking the EGF receptors on the cancer cells. This stops the EGF from activating them and, as a result, stops the cancer cells from growing and multiplying.

Gefitinib is licensed to treat advanced non-small cell lung cancer (NSCLC). It only works for NSCLCs that have changes called EGFR mutations on the surface of their cells.

Your doctor may do various tests to check the level of EGFR on your cancer cells, as this can predict if your cancer is likely to respond to the treatment.

Gefitinib tablets should be taken once daily at the same time each day, with or without food.

What is it used for?

• Non-small cell lung cancer that is locally advanced, or has spread to other areas of the body.

Warning!

• Iressa tablets should be swallowed with water. They can be taken with or without food, but must be taken at the same time each day. If you forget to take a dose you should take it as soon as you remember. However, if it is less than 12 hours until your next dose is due you should not take the missed dose. You should not take a double dose to make up for a forgotten dose.
• This medicine may sometimes cause inflammation in the lungs known as interstitial lung disease. As this can potentially be very serious you should tell your doctor straight away if you experience a worsening cough, shortness of breath, or breathing difficulties while taking this medicine, or if you get a fever.
• Your doctor will want you to have regular blood tests to monitor your liver function while you are having treatment with this medicine.
• If you experience severe or persistent diarrhoea, nausea, loss of appetite, or vomiting you should let your doctor know immediately, as if left unchecked these symptoms could result in dehydration that needs treating in hospital.
• Mouth ulcers and inflammation of the lining of the mouth are common side effects experienced by people taking this medicine. It is important to speak to your doctor before treating any mouth ulcers.
• If your eyesight or eyes seem to be affected by this medicine, you should consult your doctor immediately.
• This medicine could be harmful to a developing baby. Women who could get pregnant must use a reliable method of contraception to avoid getting pregnant while taking this medicine. Seek further medical advice from your doctor. Tell your doctor immediately if you think you could be pregnant during treatment.

Use with caution in

• People with moderate to severely decreased liver function due to liver cirrhosis.
• People with moderate to severely decreased kidney function.

Not to be used in

• Breastfeeding.
• This medicine is not recommended for children and adolescents under 18 years of age, as its safety and effectiveness have not been studied in this age group.
• Rare hereditary problems of galactose intolerance, the Lapp lactase deficiency or glucose-galactose malabsorption (Iressa tablets contain lactose).

This medicine should not be used if you are allergic to any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.

If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.

Pregnancy and breastfeeding

Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.

• This medicine could be harmful to a developing baby. It should not be used during pregnancy. Women who could get pregnant must use a reliable method of contraception to avoid getting pregnant whilst taking this medicine. Seek further medical advice from your doctor.
• It is not known if this medicine passes into breast milk. Mothers who need to take this medicine should not breastfeed, because if the medicine does pass into the breast milk it could be harmful to a nursing infant. Seek medical advice from your doctor.

Side effects

Medicines and their possible side effects can affect individualpeople in different ways. The following are some of the side effects that areknown to be associated with this medicine. Just because a side effect is statedhere does not mean that all people using this medicine will experience thator any side effect.

Very common (affect more than 1 in 10 people)

• Skin reactions, such as an acne-like rash, dry skin and itchy skin. Tell your doctor if you experience any skin problems, as they can help you to manage them.
• Diarrhoea. See warning section above. Persistent andsevere diarrhoea may lead to dehydration, low blood potassium and kidney failure, particularly if you receive otherchemotherapy treatments at the same time.
• Nausea and vomiting.
• Mouth ulcers.
• Inflammation of the lining of the mouth (stomatitis).
• Loss of appetite.
• Weakness or loss of strength (asthenia).

Common (affect between 1 in 10 and 1 in 100 people)

• Nosebleeds.
• Blood in the urine.
• Inflammation of the eyes (conjunctivitis).
• Inflammation of the eyelids (blepharitis).
• Dry eyes.
• Dry mouth.
• Dehydration as a result of diarrhoea, vomiting or loss of appetite.
• Nail disorders.
• Hair loss.
• Fever.
• A form of lung inflammation called interstitial lung disease (see warning section above).
• Abnormal liver function.
• Cystitis.

Uncommon (affect between 1 in 100 and 1 in 1000 people)

• Inflammation of the pancreas (pancreatitis).
• Perforation of the gut.
• Inflammation of the liver (hepatitis).
• Ingrowing eyelashes.
• Ulceration or perforation of the cornea.
• Allergic reactions such as itchy, blistering skin rash (urticaria) or swelling of the lips, tongue and throat (angioedema).

Rare (affect between 1 in 1000 and 1 in 10,000 people)

• Severe blistering or peeling skin reactions, eg Steven's Johnson syndrome or toxic epidermal necrolysis.

The side effects listed above may not include all of the sideeffects reported by the medicine'smanufacturer.

For moreinformation about any other possible risks associated with this medicine,please read the information provided with the medicine or consult your doctoror pharmacist.

How can this medicine affect other medicines?

It is important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start treatment with this medicine. Similarly, check with your doctor or pharmacist before taking any new medicines while taking this one, to ensure that the combination is safe.

The following medicines can increase the breakdown of gefitinib by the liver and so may make it less effective. These should be avoided while you are taking gefitinib:

• barbiturates
• carbamazepine
• phenytoin
• rifampicin
• the herbal remedy St John's wort (Hypericum perforatum).

The following medicines may prevent the breakdown of gefitinib by the liver and so increase the amount of gefitinib in the blood. As this could increase the chance of side effects, you should be closely monitored by your doctor if you are prescribed any of these while taking gefitinib:

• clarithromycin
• itraconazole
• ketoconazole
• nefazodone
• posaconazole
• protease inhibitors such as ritonavir and saquinavir
• telithromycin
• voriconazole.

The following medicines used to reduce the acidity in the stomach may reduce the absorption of gefitinib from the gut. As they could make the gefitinib less effective, these medicines should be avoided where possible during your treatment:

• antacids for indigestion or heartburn (if taken regularly near the time of taking gefitinib)
• H₂ antagonists, eg cimetidine, ranitidine
• proton pump inhibitors, eg omeprazole, lansoprazole.

Getitinib may increase the anti-blood-clotting effects of anticoagulant medicines such as warfarin, which could increase the risk of bleeding. If you are taking an anticoagulant in combination with gefitinib, your blood clotting time (INR) should be monitored more frequently.

Other medicines containing the same active ingredient

There are currently no other medicines available in the UK that contain gefitinib as the active ingredient.