Imatinib

Imatinib is a prescription medication used to treat certain types of leukemia (cancer that starts in the white blood cells), cancers of the red blood cells, and certain kinds of tumors. Imatinib belongs to a group of drugs called protein-kinase inhibitors. It works by preventing the growth and spread of cancer cells.

This medication comes in tablet form and is taken once or twice a day, with food and a glass of water. 

Common side effects include fluid retention, vomiting, and diarrhea. Imatinib can cause drowsiness, blurred vision, and dizziness.  Do not drive or operate machinery until you know how imatinib will affect you.

Imatinib is a prescription medication used to treat various types of cancers including:

• certain types of leukemia (cancer that begins in the white blood cells) and other cancers of the blood cells.
• gastrointestinal stromal tumors (GIST; a type of tumor that grows in the walls of the digestive passages and may spread to other parts of the body). 
• dermatofibrosarcoma protuberans (a tumor that forms under the top layer of skin) when the tumor cannot be removed surgically, has spread to other parts of the body, or has come back after surgery. 

This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.

Imatinib may be found in some form under the following brand names:

• Gleevec

See "Drug Precautions" for serious side effects.

Common side effects include:

This is not a complete list of imatinib side effects. Ask your doctor or pharmacist for more information.

Tell your doctor about the medicines you take including prescription and nonprescription medications, vitamins, and herbal and nutritional supplements. Especially tell your doctor if you take:

• acetaminophen (Tylenol);
• certain antibiotics including erythromycin (E.E.S., E-Mycin, Erythrocin), clarithromycin (Biaxin), and rifampin (Rifadin, in Rifamate);
• anticoagulants ('blood thinners') such as warfarin (Coumadin);
• antifungals such as ketoconazole (Nizoral) and itraconazole (Sporanox);
• calcium channel blockers such as amlodipine (Norvasc, in Caduet), diltiazem (Cardizem, Tiazac), felodipine (Plendil), isradipine (Dynacirc), nicardipine (Cardene), nifedipine (Adalat, Procardia, others), nimodipine (Nimotop), nisoldipine (Sular), or verapamil (Calan, Covera, Isoptin, Verelan);
• cholesterol-lowering medications (statins) such as atorvastatin (Lipitor), lovastatin (Mevacor), and simvastatin (Zocor);
• cyclosporine (Neoral, Sandimmune);
• dexamethasone;
• hormonal contraceptives (birth control pills, patches, rings, injections or implants);
• pimozide (Orap);
• medications for anxiety;
• medications for seizures such as carbamazepine (Tegretol), phenobarbital, and phenytoin (Dilantin);
• sedatives;
• sleeping pills;
• tranquilizers 
• St. John's wort
• iron supplements

Do not take any other medications without talking to your doctor or pharmacist first, including over-the-counter medications such as Tylenol (acetaminophen); herbal products (St. John's wort, Hypericum perforatum); or prescription medications including Coumadin (warfarin sodium); rifampin; erythromycin; metoprolol; ketoconazole; and Dilantin (phenytoin). Taking these with imatinib may affect how they work, or affect how imatinib works.

Do not take medicines to treat diarrhea while you are taking imatinib without talking to your doctor.

You should also tell your doctor if you are taking or plan to take iron supplements. Patients should also avoid grapefruit juice and other foods that may affect how imatinib works.

Serious side effects have been reported with imatinib including the following:

• Imatinib is often associated with edema (swelling) and serious fluid retention (holding water). It is important that patients be weighed and monitored regularly for signs and symptoms of serious fluid retention or unexpected weight gain. Patients experiencing unexpected, rapid weight gain should speak to their doctor about appropriate supportive care treatment. Studies have shown that edema tended to occur more often among patients who are 65 and older or those taking higher doses of imatinib. If you experience severe fluid retention, your doctor may treat you with diuretics and may stop your imatinib treatment until the fluid retention has been managed. Treatment can be returned as appropriate depending on the initial severity of the event.
• Cytopenias (reduction or lack of certain cell elements in blood circulation) have occurred. Your doctor will test your blood weekly for the first month, biweekly for the second month, and periodically thereafter. In most cases, your doctor will reduce or interrupt your imatinib therapy; in rare cases, if the cytopenia is severe, your doctor may discontinue treatment.
• Severe congestive heart failure (impaired ability of the heart to pump blood) and left ventricular dysfunction (impaired functioning of the left side of the heart) have been reported, particularly in patients with other health issues and risk factors. Patients with heart disease or risk factors for heart disease or history of renal failure will be monitored and treated for the condition.
• Severe liver problems (hepatotoxicity) may occur. Cases of fatal liver failure and severe liver injury requiring liver transplants have been reported with both short-term and long-term use of imatinib. Your doctor will check your liver function before beginning treatment and continue to monitor liver function as needed. If you experience severe liver problems, your doctor may stop your treatment with imatinib until the liver problem has been managed.
• Bleeding may occur. Severe gastrointestinal (GI) bleeding has been reported in patients with Ph+ chronic myelogenous leukemia (CML) and KIT+ gastrointestinal stromal tumor (GIST). GI tumor sites may be the cause of this bleeding; therefore, GI symptoms should be monitored at the start of treatment.
• Gastrointestinal (GI) perforation (small holes or tears in the wall of the stomach or intestine), in some cases fatal, has been reported.
• In patients with hypereosinophilic syndrome (a condition with increased eosinophils, which are a type of white blood cell), e.g., HES, MDS/MPD, or ASM and heart involvement, cases of heart disease have been associated with the initiation of imatinib therapy. Speak to your doctor regarding appropriate supportive care or discontinuing imatinib.
• Skin reactions, such as fluid-filled blisters, have been reported with the imatinib use.
• Clinical cases of hypothyroidism (reduction in thyroid hormones) have been reported in patients taking levothyroxine replacement during treatment with imatinib. Your doctor should closely monitor your thyroid hormone levels.
• Long-term use may result in potential liver, kidney, and/or heart toxicities. Immune system suppression may also result from long-term use.
• Imatinib can cause harm to the unborn child when administered to a pregnant woman. Women should be aware of the potential harm to the fetus. Be sure to inform your doctor if you are or think you may be pregnant. You should not breastfeed while taking imatinib.
• Growth retardation (slowing of growth) has been reported in children taking imatinib. The long-term effects of extended treatment with imatinib on growth in children are unknown. Growth retardation may be monitored in children receiving treatment.
• Cases of tumor lysis syndrome (TLS), which refers to an electrolyte disturbance caused by the breakdown of tumor cells, have been reported and can be life threatening in some cases. The patients at risk of TLS are those who have a higher number of tumor cells and whose tumors are fast growing before beginning therapy. Your doctor should monitor you closely and take appropriate precautions. Correction of clinically significant dehydration and treatment of high uric acid levels are recommended prior to initiation of imatinib.
• Motor vehicle accidents involving patients receiving imatinib have been reported. Patients should be advised that they may experience undesirable effects such as dizziness, blurred vision, or drowsiness during treatment with imatinib. Caution should be recommended when driving a car or operating machinery.

The following serious side effects have been reported by patients taking imatinib:

• Severe fluid retention (holding water), which can cause swelling around the eyes or swelling of the lower legs, lungs, and heart; fatal in rare cases
• Increased pressure in the heart or brain; fatal in rare cases
• Low levels of certain blood cells
• Heart failure
• Liver problems
• Hemorrhage (abnormal bleeding)
• Skin blistering
• Low levels of thyroid hormone

Your doctor will check you closely for any side effects to stop more serious complications from occurring. Patients with heart disease or risk factors for heart failure should also be monitored carefully.

If you are experiencing any of the above-mentioned side effects, please be sure to speak with your doctor immediately.

Do not take imatinib if you are allergic to any of the ingredients in it.

Talk to your doctor about grapefruit and grapefruit juice. These foods can interfere with how imatinib is absorbed by your body.

Tell your doctor about all of your medical conditions. Especially tell your doctor if you:

• are allergic to imatinib or any other medications
• have or have ever had hypertension (high blood pressure), heart disease, irregular heart beat, or a heart attack
• have diabetes, or lung, thyroid, or liver disease
• pregnant or breastfeeding

Tell your doctor about all of the medicines you take including prescription and non-prescription medicines, vitamins, and herbal supplements.

Tell your doctor if you are pregnant or plan to become pregnant.

The FDA categorizes medications based on safety for use during pregnancy. Five categories - A, B, C, D, and X, are used to classify the possible risks to an unborn baby when a medication is taken during pregnancy.

Imatinib falls into category D. It has been shown that use of imatinib in pregnant women caused some babies to be born with problems. However, in some serious situations, the benefit of using this medication may be greater than the risk of harm to the baby.

Imatinib has been detected in human breast milk. Because of the possibility for adverse reactions in nursing infants from imatinib, a choice should be made whether to stop nursing or to stop use of this medication. The importance of the drug to the mother should be considered.

Take imatinib exactly as your doctor prescribes it. Follow the directions on your prescription label carefully. imatinib is taken by mouth. It is usually taken with a meal and a large glass of water once or twice a day. Take imatinib at around the same time every day. 

If you are unable to swallow imatinib tablets, you may place all of the tablets that you need for one dose into a glass of water or apple juice. Use approximately 2 ounces of liquid for each 100 mg tablet and 100 milliliters (a little less than 4 ounces) of liquid for each 400 mg tablet. Stir with a spoon until the tablets crumble completely and drink the mixture immediately.

Because the tablet coating contains iron, never take eight of the 100 mg imatinib tablets. You will receive too much iron. If your doctor has told you to take 800 mg of imatinib, you should take two of the 400 mg tablets. 

If you forget to take a dose, take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

Take this medication exactly as prescribed by your doctor. Follow the directions on your prescription label carefully.

The dose your doctor recommends may be based on the following:

• the condition being treated
• other medical conditions you have
• other medications you are taking
• how you respond to this medication
• your weight
• your height
• your age
• your gender

The recommended dose range of imatinib is 100 mg/day to 800 mg/day.

If you take too much imatinib, call your local Poison Control Center or seek emergency medical attention right away. Symptoms of overdose may include muscle cramps, and swollen or bloated stomach.

• Store imatinib tablets at room temperature between 15 and 30°C (59-86°F), in a tightly sealed container to protect from moisture.
• Keep this and all medications out of the reach of children.