Gleevec (Imatinib)

At a Glance

What is Gleevec (Imatinib)?

Gleevec, also known as imatinib, is a targeted therapy used to treat certain cancers. These include chronic myeloid leukemia (CML) and gastrointestinal stromal tumors (GIST). It should be prescribed and supervised by a doctor, usually an oncologist.

How Gleevec Works

Cancer cells often depend on abnormal enzymes (tyrosine kinases) that keep sending “grow and divide” signals. Imatinib blocks three of these:

• BCR-ABL: the abnormal protein created by the Philadelphia chromosome, which drives CML.
• c-Kit: a growth-signal receptor that is overactive in many GIST cells.
• PDGF receptor: another growth-signal receptor that is involved in some of the other conditions imatinib treats.

By blocking these signals, imatinib slows the growth of these cancer cells and can cause them to die.

When Gleevec Is Used

• Chronic Myelogenous (Myeloid) Leukemia (CML): Treats Philadelphia chromosome-positive CML in adults and children, including chronic phase, accelerated phase and blast crisis.
• Gastrointestinal Stromal Tumors (GIST): Treats Kit (CD117)-positive GIST, a rare cancer of the stomach or intestines. It is used for tumors that cannot be removed or have spread, and after surgery to remove the tumor.
• Other approved uses: Ph+ acute lymphoblastic leukemia (ALL), certain myelodysplastic/myeloproliferative diseases, aggressive systemic mastocytosis, hypereosinophilic syndrome/chronic eosinophilic leukemia, and dermatofibrosarcoma protuberans (DFSP).

Dosage and How to Take It

The dose depends on the condition being treated, the stage of disease, age, kidney and liver function, other medicines, laboratory results and how well the medicine is tolerated. Other conditions treated with imatinib use different doses. The doses below follow the US prescribing information and are general information only. The treating oncologist decides the final dose for each patient.

• Adults with CML: 400 mg once daily in chronic phase and 600 mg once daily in accelerated phase or blast crisis. Doctors may consider increasing the dose (to 600 mg in chronic phase, or to 800 mg given as 400 mg twice daily in accelerated phase or blast crisis) if the disease progresses, the response is not satisfactory, or an earlier response is lost, provided there are no severe side effects.
• Adults with GIST: 400 mg daily, including after surgery. Doctors may increase it up to 800 mg daily (400 mg twice daily) if the tumor clearly progresses and there are no severe side effects.
• Children with newly diagnosed CML (chronic phase): 340 mg/m² per day (not to exceed 600 mg), given once daily or split into two doses.

Liver (hepatic) impairment

• Mild or moderate impairment: No dose adjustment is needed at the start of treatment.
• Severe impairment: The recommended dose is reduced by 25% (for example, 400 mg to 300 mg), because blood levels of imatinib and its active metabolite are higher in severe liver impairment.

Kidney (renal) impairment

Imatinib exposure in the body is about 1.5 to 2 times higher in people with mild or moderate kidney impairment, so dosing is more cautious.

• Mild impairment (creatinine clearance 40–59 mL/min): Doses above 600 mg are not recommended.
• Moderate impairment (creatinine clearance 20–39 mL/min): The recommended starting dose is reduced by 50%, and later doses may be increased as tolerated. Doses above 400 mg are not recommended.
• Severe impairment (creatinine clearance below 20 mL/min): Imatinib is used with caution because clinical data are limited.

Doctors may also change the dose when certain other medicines are used, or if liver or blood count problems develop during treatment. Do not change the dose yourself.

How to take it

Gleevec is taken with a meal and a large glass of water. If swallowing is difficult, the tablet can be dissolved in water or apple juice.

Take this medicine only as advised by your doctor or healthcare professional. Do not start, stop, or change the dose on your own.

Side Effects

Common side effects include:

• Swelling (often around the eyes or in the legs)
• Nausea, vomiting and diarrhea
• Stomach pain
• Muscle cramps and muscle or bone pain
• Skin rash
• Tiredness

Serious side effects are less common but need prompt medical attention:

• Severe fluid retention (rapid weight gain, swelling, breathlessness)
• Low blood counts (cytopenias), which can show up as infections, fever or unusual bruising
• Liver problems, including jaundice (yellowing of the skin or eyes)
• Bleeding, including in the stomach or intestines, and rare stomach or bowel perforation
• Heart failure
• Severe skin reactions such as blistering rashes or Stevens-Johnson syndrome
• Tumor lysis syndrome
• Reduced kidney function

Gleevec can also cause dizziness, blurred vision or drowsiness, so use caution when driving or operating machinery. In children, slowed growth has been reported.

Precautions and Monitoring

According to the US prescribing information, doctors may monitor:

• Complete blood counts: weekly for the first month, every two weeks for the second month, and periodically after that as clinically needed.
• Liver function: before starting treatment and then monthly, or as clinically indicated.
• Kidney function: before starting and during treatment, especially in people with existing kidney problems, diabetes, high blood pressure or heart failure.
• Body weight and fluid retention: regular weight checks, because rapid weight gain can signal fluid build-up.
• Heart function: in people with heart disease or risk factors for heart failure.
• Growth: in children and adolescents.
• Thyroid function (TSH): in people without a thyroid gland who take levothyroxine.

Tell your doctor about any heart, liver, kidney or thyroid condition before starting. Monitoring plans vary from person to person, and your doctor will decide what is right for you.

Drug Interactions

• Medicines that can lower Gleevec levels: Strong CYP3A4 inducers such as rifampin, carbamazepine, phenytoin, phenobarbital and dexamethasone can reduce its effect, and the prescribing information advises avoiding them where possible. St. John’s Wort has also been shown to lower imatinib levels. If such a medicine cannot be avoided, the doctor may adjust the Gleevec dose and monitor the response closely.
• Medicines that can raise Gleevec levels: Strong CYP3A4 inhibitors such as ketoconazole, itraconazole, clarithromycin and ritonavir can increase imatinib levels, so caution and monitoring may be needed.
• Grapefruit juice: Grapefruit juice can increase imatinib levels, so the prescribing information advises avoiding it during treatment. Follow your doctor’s advice on diet.
• Medicines whose levels Gleevec can raise: Imatinib can increase blood levels of some medicines, such as simvastatin and certain other cholesterol medicines, some calcium channel blockers, and medicines with a narrow safety margin such as cyclosporine and tacrolimus. The treating doctor may adjust treatment or monitor levels.
• Blood thinners: The prescribing information recommends standard or low-molecular-weight heparin instead of warfarin for people who need anticoagulation.
• Methotrexate: Gleevec may delay the clearance of high-dose methotrexate (above 500 mg/m²).
• Paracetamol (acetaminophen): Imatinib can affect the liver, and there are limited safety data on regular, long-term paracetamol use together with imatinib. This does not mean paracetamol is prohibited, but ask your doctor how much is safe and for how long, especially if you need it regularly.

Tell your doctor and pharmacist about all prescription medicines, over-the-counter medicines, supplements and herbal products you take. This list is not complete.

Pregnancy and Breastfeeding

Imatinib can cause fetal harm. Females of reproductive potential should have a pregnancy test before starting treatment and are advised to use effective contraception during treatment and for 14 days after stopping. If you are pregnant or become pregnant while taking Gleevec, tell your doctor right away.

Imatinib passes into breast milk. Breastfeeding is not advised during treatment and for 1 month after the last dose.

Brands, Strengths and Approximate Price in India

• Examples of imatinib brands available in India may include Glivec (Novartis), Veenat (Natco), Imatib (Cipla) and Lupinib (Lupin). This is not a complete list, and imatinib is the generic name.
• Strengths: The US Gleevec prescribing information lists 100 mg and 400 mg tablets. Indian generic brands do not all offer identical strengths or pack sizes, so check the strength of the specific product with your pharmacist or doctor. The 400 mg tablet is the strength most commonly listed for these brands in India.
• Approximate price in India: ₹1,530–₹2,385 per strip of 10 tablets (400 mg), based on the brands above.

Prices may vary by brand, strength, pack size, pharmacy and location.

How HealthPil Can Help

Medicines should be started, adjusted, or stopped only under the guidance of a qualified healthcare professional. If you have questions about this medicine, its side effects, or your treatment plan, you can consult an oncologist through HealthPil.