Imatinib Zentiva: Uses, Dosage & Side Effects
A targeted tyrosine kinase inhibitor for the treatment of chronic myeloid leukemia (CML), gastrointestinal stromal tumors (GIST), and other Philadelphia chromosome-positive or KIT-driven malignancies
Imatinib Zentiva is a prescription tyrosine kinase inhibitor (TKI) containing imatinib mesylate, used primarily for the treatment of chronic myeloid leukemia (CML) and gastrointestinal stromal tumors (GIST). It works by selectively blocking the BCR-ABL fusion protein created by the Philadelphia chromosome in CML, as well as the c-KIT and PDGFR tyrosine kinases involved in GIST and other malignancies. Imatinib revolutionized cancer treatment when it was first approved in 2001 and is recognized by the World Health Organization as an essential medicine. Imatinib Zentiva is a generic formulation that offers the same proven efficacy and safety profile as the originator product, available as 100 mg film-coated tablets taken orally once or twice daily with food.
Quick Facts: Imatinib Zentiva
Key Takeaways
- Imatinib Zentiva is a generic formulation of imatinib mesylate, the groundbreaking tyrosine kinase inhibitor that transformed chronic myeloid leukemia from a fatal disease into a manageable chronic condition, with 10-year overall survival rates exceeding 80%.
- It works by selectively inhibiting the BCR-ABL, c-KIT, and PDGFR tyrosine kinases, making it effective against CML in all phases, GIST, and several other rare cancers driven by these molecular targets.
- The standard dose for chronic-phase CML is 400 mg once daily, taken with a meal and a large glass of water. Doses may be increased to 600–800 mg daily depending on response and tolerability.
- Common side effects include nausea, edema, muscle cramps, diarrhea, and skin rash. Regular blood count monitoring and liver function tests are essential throughout treatment due to risks of myelosuppression and hepatotoxicity.
- Significant drug interactions exist with CYP3A4 inhibitors and inducers (such as ketoconazole, rifampicin, and St John’s Wort), and imatinib can itself alter the metabolism of other medications including warfarin and simvastatin.
What Is Imatinib Zentiva and What Is It Used For?
Imatinib Zentiva contains the active substance imatinib (as imatinib mesylate), a potent and selective inhibitor of several tyrosine kinases—enzymes that play critical roles in cell signaling, growth, and survival. It belongs to the class of drugs known as tyrosine kinase inhibitors (TKIs) and represents one of the most important breakthroughs in the history of targeted cancer therapy. Imatinib Zentiva is a generic formulation, meaning it contains the same active ingredient, at the same strength, and has demonstrated bioequivalence to the originator product (Gleevec/Glivec, originally developed by Novartis). Generic imatinib products have been approved by the European Medicines Agency (EMA), the U.S. Food and Drug Administration (FDA), and regulatory authorities worldwide after rigorous evaluation of quality, safety, and efficacy.
The development of imatinib is widely regarded as one of the landmark achievements in modern oncology. The story begins with the discovery of the Philadelphia chromosome in the early 1960s—an abnormal chromosomal translocation, designated t(9;22)(q34;q11), found in over 95% of patients with chronic myeloid leukemia. This translocation results in the fusion of the BCR gene on chromosome 22 with the ABL1 gene on chromosome 9, creating the BCR-ABL fusion oncogene. The BCR-ABL protein is a constitutively active tyrosine kinase that drives uncontrolled proliferation of white blood cells, the hallmark of CML. By the late 1990s, researchers had identified imatinib (originally known as STI571 or CGP57148B) as a molecule capable of fitting precisely into the ATP-binding pocket of the BCR-ABL kinase, effectively shutting off the molecular switch that drives leukemic cell growth.
In addition to BCR-ABL, imatinib also inhibits several other tyrosine kinases with important therapeutic implications. It blocks the receptor tyrosine kinase c-KIT (also known as CD117 or stem cell factor receptor), which is constitutively activated by gain-of-function mutations in the vast majority of gastrointestinal stromal tumors (GIST). Imatinib also inhibits the platelet-derived growth factor receptors alpha and beta (PDGFR-α and PDGFR-β), which are implicated in conditions such as dermatofibrosarcoma protuberans, hypereosinophilic syndrome, and chronic eosinophilic leukemia. Furthermore, it inhibits the discoidin domain receptors DDR1 and DDR2, colony-stimulating factor 1 receptor (CSF-1R), and the ABL-related gene product ARG. This multi-target activity expands the therapeutic utility of imatinib beyond CML to a range of molecularly defined cancers and hematologic disorders.
The approved indications for imatinib include:
- Chronic myeloid leukemia (CML): Treatment of adult and pediatric patients with newly diagnosed Philadelphia chromosome-positive (Ph+) CML in the chronic phase, as well as patients in the accelerated phase, blast crisis, or chronic phase after failure of interferon-alpha therapy. Imatinib is the first-line standard of care for newly diagnosed chronic-phase CML according to both ESMO and NCCN guidelines.
- Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL): Treatment of adult patients with newly diagnosed Ph+ ALL, typically in combination with chemotherapy, and as maintenance therapy.
- Gastrointestinal stromal tumors (GIST): Treatment of adult patients with unresectable and/or metastatic KIT-positive GIST, and as adjuvant therapy following complete resection of KIT-positive GIST at significant risk of recurrence.
- Myelodysplastic/myeloproliferative diseases (MDS/MPD): Treatment of adult patients with MDS/MPD associated with PDGFR gene rearrangements.
- Hypereosinophilic syndrome (HES) and chronic eosinophilic leukemia (CEL): Treatment of adult patients with HES and/or CEL with FIP1L1-PDGFR-α rearrangement.
- Dermatofibrosarcoma protuberans (DFSP): Treatment of adult patients with unresectable, recurrent, and/or metastatic DFSP.
- Aggressive systemic mastocytosis (ASM): Treatment of adult patients with ASM without the D816V c-KIT mutation or with unknown c-KIT mutational status.
The clinical evidence supporting imatinib in CML is among the strongest in oncology. The International Randomized Study of Interferon versus STI571 (IRIS) trial, initiated in June 2000, enrolled 1,106 patients with newly diagnosed chronic-phase CML. The results were transformative: at 18 months, the rate of complete cytogenetic response (CCyR) was 76% in the imatinib group versus 15% in the interferon-alpha plus cytarabine group. Long-term follow-up at 10 years demonstrated that imatinib-treated patients achieved an estimated overall survival rate of 83.3%, fundamentally changing the prognosis of CML from a median survival of 3–5 years with previous therapies to near-normal life expectancy for many patients who achieve and maintain molecular remission.
For GIST, the pivotal phase III trial by Demetri et al. (2002), published in the New England Journal of Medicine, demonstrated that imatinib 400 mg daily achieved partial responses in 54% of patients and stable disease in 28%, with a dramatic improvement in progression-free survival compared with historical controls. Subsequent studies established imatinib as the standard of care for both metastatic and adjuvant treatment of GIST, with 3 years of adjuvant therapy recommended for high-risk resected tumors based on the SSG XVIII/AIO trial results.
Imatinib was the first successful targeted cancer therapy and is often described as the drug that proved that understanding the molecular biology of cancer could lead to transformative treatments. It was approved by the FDA in May 2001 after one of the fastest regulatory reviews in history, based on the remarkable efficacy seen in early clinical trials. In 2015, the WHO added imatinib to its Model List of Essential Medicines, recognizing its critical importance in global cancer treatment. The story of imatinib serves as a model for modern precision oncology, inspiring the development of dozens of subsequent targeted therapies across multiple cancer types.
What Should You Know Before Taking Imatinib Zentiva?
Contraindications
The primary contraindication for Imatinib Zentiva is hypersensitivity (allergy) to imatinib or to any of the excipients listed in the formulation. The excipients in Imatinib Zentiva 100 mg film-coated tablets typically include microcrystalline cellulose, crospovidone, hydroxypropyl cellulose, colloidal anhydrous silica, and magnesium stearate in the tablet core, with a film coating containing hypromellose, iron oxide yellow, iron oxide red, macrogol, and talc. If you have a known allergy to any of these components, inform your doctor before starting treatment.
There are no absolute contraindications based on specific diseases, but imatinib requires careful monitoring and dose adjustment in several clinical situations. Patients with severe hepatic impairment should use imatinib with caution, as the drug is extensively metabolized by the liver and impaired hepatic function can lead to increased drug exposure and toxicity. Similarly, patients with severe renal impairment (creatinine clearance below 20 mL/min) have limited data available and should be treated with caution.
Warnings and Precautions
Treatment with imatinib requires regular monitoring of complete blood counts (weekly for the first month, biweekly for the second month, then periodically thereafter), liver function tests (before treatment and monthly or as clinically indicated), and assessment of fluid retention. Dose modifications or treatment interruption may be necessary based on these results.
Before starting and during treatment with Imatinib Zentiva, your doctor should be aware of the following:
- Hepatotoxicity: Imatinib is metabolized primarily in the liver and can cause elevations in liver enzymes (transaminases) and bilirubin. Severe hepatotoxicity, including hepatic failure requiring liver transplantation, has been reported in rare cases. Liver function tests should be performed before initiation of treatment and monthly thereafter, or as clinically indicated. If abnormalities in liver function are detected, imatinib dose should be reduced or treatment interrupted. Patients with pre-existing liver disease should be closely monitored.
- Fluid retention: Imatinib can cause fluid retention, which may manifest as periorbital edema (swelling around the eyes), peripheral edema (swelling of the legs and ankles), pleural effusion (fluid around the lungs), pericardial effusion (fluid around the heart), pulmonary edema, or ascites (fluid in the abdomen). Fluid retention is dose-dependent and more common in elderly patients, those taking higher doses, and patients with pre-existing cardiac or renal conditions. Patients should be weighed regularly. Unexpected rapid weight gain should be carefully investigated and managed promptly.
- Myelosuppression: Imatinib commonly causes cytopenias, including neutropenia, thrombocytopenia, and anemia. These are particularly frequent during the first months of treatment. Complete blood counts should be performed weekly during the first month, biweekly during the second month, and periodically thereafter. Dose reductions or treatment interruptions may be required.
- Cardiac disorders: Cardiac failure (including congestive heart failure and left ventricular dysfunction) has been reported, particularly in patients with risk factors such as advanced age, pre-existing cardiac disease, renal impairment, or co-morbidities including diabetes. Patients with cardiac risk factors should be monitored carefully, and any signs or symptoms of heart failure should be evaluated and treated promptly.
- Gastrointestinal hemorrhage: In GIST patients, gastrointestinal hemorrhage and tumor hemorrhage have been reported. These may be related to tumor necrosis in response to imatinib treatment. Patients should be monitored for gastrointestinal symptoms, and bleeding events should be managed appropriately.
- Tumor lysis syndrome (TLS): TLS has been reported in patients with CML and GIST treated with imatinib, particularly those with high tumor burden. Adequate hydration and management of uric acid levels prior to initiating treatment are recommended, especially in patients with high white blood cell counts or large tumor volumes.
- Growth retardation in children: Cases of growth retardation have been reported in children and pre-adolescents receiving imatinib. Long-term effects of prolonged treatment on growth in children are not known. Close monitoring of growth in pediatric patients is recommended.
- Hypothyroidism: Clinical cases of hypothyroidism have been reported in thyroidectomized patients receiving levothyroxine replacement during imatinib treatment. Thyroid-stimulating hormone (TSH) levels should be closely monitored in these patients.
Pregnancy and Breastfeeding
Imatinib should not be used during pregnancy unless clearly necessary and only if the potential benefit justifies the potential risk to the fetus. Animal studies have shown reproductive toxicity, and there is a potential risk of harm to the developing baby. Women of childbearing potential should be advised to use effective contraception during treatment and for at least 15 days after the last dose. If imatinib is used during pregnancy, or if the patient becomes pregnant while taking the drug, she should be informed of the potential hazard to the fetus.
Both imatinib and its active metabolite N-desmethyl imatinib can be excreted in human breast milk. Based on data from three breastfeeding women, the milk-to-plasma ratio was estimated at 0.5 for imatinib and 0.9 for the active metabolite. Given the known pharmacological activity of imatinib and the potential for serious adverse reactions in breastfed infants, women should not breastfeed during treatment and for at least 15 days after the last dose.
Driving and Operating Machinery
Patients should be advised that they may experience side effects such as dizziness, blurred vision, or drowsiness during treatment with imatinib. If these symptoms occur, caution should be exercised when driving or operating machinery. While imatinib itself does not appear to directly impair cognitive function, the general effects of cancer treatment and associated fatigue may affect a patient's ability to perform tasks requiring concentration.
Reactivation of hepatitis B has occurred in patients who are chronic carriers of the virus after receiving BCR-ABL tyrosine kinase inhibitors including imatinib. Some cases resulted in acute hepatic failure or fulminant hepatitis, leading to liver transplantation or death. Patients should be tested for hepatitis B virus (HBV) infection before initiating imatinib treatment. Patients with positive HBV serology should be monitored closely throughout treatment and for several months after treatment discontinuation.
How Does Imatinib Zentiva Interact with Other Drugs?
Unlike many monoclonal antibodies, imatinib is a small-molecule drug that is extensively metabolized by the cytochrome P450 (CYP) enzyme system in the liver. This metabolic profile means that imatinib has a complex and clinically significant drug interaction potential that both patients and prescribers must carefully consider. Understanding these interactions is critical because both increased and decreased imatinib exposure can have serious consequences—higher levels increase the risk of toxicity, while lower levels may compromise treatment efficacy and disease control.
Imatinib is primarily metabolized by cytochrome P450 3A4 (CYP3A4), with minor contributions from CYP1A2, CYP2D6, CYP2C9, and CYP2C19. Its main active metabolite, N-desmethyl-imatinib (CGP74588), is formed primarily by CYP3A4 and has in vitro potency similar to the parent compound. Imatinib is also an inhibitor of CYP3A4, CYP2D6, CYP2C9, and CYP2C19, meaning it can raise plasma levels of other drugs metabolized by these enzymes.
Major Interactions
| Drug / Class | Effect | Clinical Significance |
|---|---|---|
| Ketoconazole, Itraconazole (CYP3A4 inhibitors) | Increased imatinib plasma levels (up to 40% increase in AUC) | Risk of increased toxicity; use with caution |
| Rifampicin (CYP3A4 inducer) | Decreased imatinib levels by up to 74% | May render treatment ineffective; avoid concomitant use |
| Phenytoin, Carbamazepine, Phenobarbital | Decreased imatinib levels (CYP3A4 induction) | Reduced efficacy; consider alternatives or dose increase |
| St John’s Wort (Hypericum perforatum) | Decreased imatinib levels (CYP3A4 induction) | Avoid concomitant use; may cause treatment failure |
| Warfarin (coumarin anticoagulant) | Imatinib inhibits CYP2C9 and CYP3A4 metabolism of warfarin | Use LMWH instead; if warfarin is essential, monitor INR closely |
| Simvastatin (CYP3A4 substrate) | Imatinib increases simvastatin exposure by approximately 3.5-fold | Increased risk of myopathy and rhabdomyolysis |
| Ciclosporin, Tacrolimus | Increased levels of ciclosporin/tacrolimus (CYP3A4 inhibition) | Monitor drug levels closely; dose adjustment may be needed |
Minor Interactions and Other Considerations
| Drug / Substance | Effect | Recommendation |
|---|---|---|
| Paracetamol (acetaminophen) | Imatinib inhibits O-glucuronidation of paracetamol in vitro | Use with caution at high doses; monitor liver function |
| Levothyroxine | Increased TSH levels in thyroidectomized patients | Monitor TSH regularly; dose adjustment may be needed |
| Grapefruit juice | Inhibits CYP3A4 in the gut; may increase imatinib levels | Avoid or limit grapefruit juice consumption |
| Metoprolol (CYP2D6 substrate) | Imatinib inhibits CYP2D6; may increase metoprolol exposure | Monitor for increased beta-blocker effects |
| Proton pump inhibitors | No significant effect on imatinib absorption | Can be used concomitantly |
It is critically important that patients inform their oncologist, pharmacist, and all healthcare providers about every medication they are taking, including over-the-counter drugs, herbal supplements, vitamins, and dietary supplements. Even seemingly harmless herbal products such as St John’s Wort can have profound effects on imatinib efficacy. Similarly, patients should be aware that grapefruit and grapefruit juice can inhibit CYP3A4 in the gut wall, potentially increasing imatinib absorption and plasma levels.
Patients requiring anticoagulation should discuss alternatives with their doctor. Because imatinib inhibits both CYP2C9 and CYP3A4, which are involved in warfarin metabolism, co-administration can lead to unpredictable changes in INR (International Normalized Ratio). Current guidelines recommend using low-molecular-weight heparin (LMWH) instead of warfarin in patients receiving imatinib. If warfarin must be used, frequent INR monitoring is essential.
Always carry an up-to-date list of all medications and supplements you are taking to every medical appointment. Before starting any new medication—including over-the-counter drugs or herbal remedies—check with your oncologist or pharmacist. Avoid grapefruit juice during imatinib treatment. Do not stop or change the dose of imatinib without consulting your doctor, as maintaining adequate drug levels is critical for treatment success.
What Is the Correct Dosage of Imatinib Zentiva?
Imatinib Zentiva should always be taken exactly as prescribed by your doctor. The tablets should be swallowed whole with a large glass of water during a meal to reduce the risk of gastrointestinal irritation. Do not crush, break, or chew the tablets. For patients who are unable to swallow the film-coated tablets, they may be dispersed in a glass of still water or apple juice. The required number of tablets should be placed in the appropriate volume of liquid (approximately 50 mL for a 100 mg tablet or 200 mL for a 400 mg dose) and stirred until dissolved. The resulting suspension should be consumed immediately after dissolution.
Adults
| Indication | Starting Dose | Dose Escalation | Duration |
|---|---|---|---|
| CML Chronic Phase | 400 mg once daily | Up to 600–800 mg daily | Continuous (lifelong or until TFR eligible) |
| CML Accelerated Phase | 600 mg once daily | Up to 800 mg (400 mg twice daily) | Continuous |
| CML Blast Crisis | 600 mg once daily | Up to 800 mg (400 mg twice daily) | Continuous |
| Ph+ ALL | 600 mg once daily | Up to 800 mg | Per treatment protocol |
| GIST (metastatic/unresectable) | 400 mg once daily | Up to 800 mg (400 mg twice daily) | Continuous until progression |
| GIST (adjuvant) | 400 mg once daily | Not typically escalated | 3 years for high-risk; 1 year otherwise |
| MDS/MPD, HES/CEL | 400 mg once daily | Variable by response | Continuous |
| DFSP | 800 mg daily (400 mg twice) | Not typically escalated | Until progression or surgery |
Children and Adolescents
Imatinib is approved for the treatment of children and adolescents with newly diagnosed Ph+ CML and Ph+ ALL. The recommended dose in pediatric patients is calculated based on body surface area (BSA):
Pediatric Dosing (CML Chronic Phase)
Dose: 340 mg/m²/day (not exceeding 600 mg total daily dose)
The daily dose can be administered once daily or split into two doses (morning and evening). The dose should be recalculated as the child grows. Tablets can be dispersed in water or apple juice for children who cannot swallow whole tablets.
Pediatric Dosing (Ph+ ALL)
Dose: 340 mg/m²/day (not exceeding 600 mg total daily dose), in combination with chemotherapy as defined by the treatment protocol.
There is no experience with imatinib treatment in children under 1 year of age. Growth monitoring should be performed at regular intervals in all pediatric patients receiving long-term imatinib therapy.
Elderly Patients
No specific dose adjustments are required based on age alone. However, elderly patients may be more susceptible to certain side effects, particularly fluid retention, cardiac failure, and myelosuppression. Renal function declines naturally with age, and since renal impairment can increase imatinib exposure, dose adjustments may be needed based on renal function. Close monitoring is recommended, especially during the initial months of therapy.
Missed Dose
If you miss a dose, take it as soon as you remember, unless it is almost time for your next scheduled dose. In that case, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you vomit within 30 minutes of taking imatinib, you may retake the dose; otherwise, wait until the next scheduled dose. Consistent adherence to the prescribed dosing schedule is critical for maintaining therapeutic drug levels and achieving optimal treatment outcomes. Studies have shown that adherence rates below 80% are associated with significantly worse molecular responses in CML patients.
Overdose
In the event of overdose, seek immediate medical attention. There is no specific antidote for imatinib. Overdose may result in exaggerated pharmacological effects, including severe myelosuppression, hepatotoxicity, and fluid retention. Treatment is supportive: monitor blood counts and liver function, manage fluid balance, and consider gastric lavage if the overdose was recent. Imatinib is highly protein-bound and is not expected to be significantly removed by dialysis.
Experience with doses greater than 800 mg is limited. Cases of overdose have been reported with doses up to 6,400 mg (16 tablets of 400 mg). Symptoms reported in overdose cases include nausea, vomiting, diarrhea, rash, erythema, edema, swelling, fatigue, muscle spasms, thrombocytopenia, pancytopenia, abdominal pain, headache, and decreased appetite. In the event of overdose, patients should be observed and appropriate supportive treatment given.
What Are the Side Effects of Imatinib Zentiva?
Like all medicines, Imatinib Zentiva can cause side effects, although not everybody gets them. Most side effects are mild to moderate in severity and can often be managed with dose adjustments, supportive care, or temporary treatment interruptions. The side effect profile of imatinib is well characterized based on extensive clinical trial data and over two decades of post-marketing surveillance involving millions of patients worldwide.
The frequency and severity of side effects may vary depending on the underlying disease being treated, the dose of imatinib, the duration of treatment, and individual patient factors. Side effects tend to be more frequent and severe at higher doses (600–800 mg) compared with the standard 400 mg dose. Many side effects, particularly gastrointestinal symptoms and edema, tend to be most prominent during the first few months of treatment and may diminish over time as the body adjusts to the medication.
Very Common (affects more than 1 in 10 patients)
These effects are experienced by the majority of patients
- Nausea
- Vomiting
- Diarrhea
- Periorbital edema (swelling around the eyes)
- Peripheral edema (swelling of legs/ankles)
- Muscle cramps and musculoskeletal pain
- Skin rash and dermatitis
- Fatigue
- Abdominal pain
- Headache
- Neutropenia (low white blood cells)
- Thrombocytopenia (low platelets)
- Anemia (low red blood cells)
- Weight gain
- Decreased appetite
Common (affects 1 in 10 to 1 in 100 patients)
These effects are experienced by some patients
- Upper respiratory tract infections
- Dizziness
- Insomnia
- Paresthesia (tingling/numbness)
- Blurred vision and dry eyes
- Conjunctivitis
- Increased lacrimation (watery eyes)
- Dyspepsia and flatulence
- Constipation
- Liver enzyme elevations (AST/ALT)
- Pruritus (itching)
- Alopecia (hair thinning)
- Night sweats
- Joint pain and bone pain
- Pyrexia (fever)
- Pleural effusion
Uncommon (affects 1 in 100 to 1 in 1,000 patients)
These effects are less frequent
- Congestive heart failure
- Pericardial effusion
- Pulmonary edema
- Hepatitis and jaundice
- Acute renal failure
- Gastrointestinal hemorrhage
- Tumor hemorrhage/tumor necrosis
- Pancreatitis
- Depression
- Memory impairment
- Erectile dysfunction
- Gynecomastia
- Photosensitivity
Rare (affects fewer than 1 in 1,000 patients)
These effects are infrequent but may be serious
- Hepatic failure (including fatal cases)
- Tumor lysis syndrome
- Interstitial lung disease / pulmonary fibrosis
- Avascular necrosis of bone
- Stevens-Johnson syndrome
- Angioedema
- Cardiac tamponade
- Rhabdomyolysis / myopathy
- Growth retardation in children
- Hepatitis B reactivation
If you experience any side effects, talk to your doctor, pharmacist, or nurse. This includes any possible side effects not listed above. You should contact your doctor immediately if you experience signs of serious adverse reactions, including: sudden weight gain, swelling of the face or legs, difficulty breathing, yellowing of the skin or eyes (jaundice), dark urine, unusual bleeding or bruising, severe skin reactions, chest pain, persistent vomiting, or high fever.
Long-term treatment with imatinib (over many years) may be associated with cumulative toxicities. Particular attention should be paid to renal function, phosphate and calcium metabolism (hypophosphatemia has been reported), and cardiac function. Patients on long-term therapy should have regular assessments including renal function tests, bone density evaluations (if clinically indicated), and echocardiography or cardiac monitoring as appropriate.
How Should You Store Imatinib Zentiva?
Proper storage of Imatinib Zentiva is important to ensure the medication remains effective and safe throughout its shelf life. The following storage guidelines should be observed:
- Temperature: Store below 30°C (86°F). Do not refrigerate or freeze. Room temperature storage is appropriate in most environments.
- Moisture protection: Store in the original blister pack or container to protect from moisture. Do not transfer tablets to pill organizers for extended periods, as this may expose them to humidity that can degrade the film coating.
- Light: No special precautions regarding light are required, but keeping tablets in the original packaging is recommended.
- Children: Keep out of the reach and sight of children. Imatinib is a cytotoxic medication, and accidental ingestion by children could be extremely harmful.
- Expiry date: Do not use Imatinib Zentiva after the expiry date printed on the carton and blister. The expiry date refers to the last day of the stated month.
- Disposal: Do not dispose of unused or expired tablets in household waste or via wastewater. Return unused medication to your pharmacist for safe disposal in accordance with local regulations. As a cytotoxic agent, imatinib requires appropriate handling and disposal to minimize environmental contamination.
If you notice any visible changes to the tablets, such as discoloration, crumbling, or an unusual odor, do not take them. Consult your pharmacist for a replacement supply.
What Does Imatinib Zentiva Contain?
Understanding the composition of your medication can be important, particularly if you have known allergies or intolerances to specific ingredients. Each Imatinib Zentiva 100 mg film-coated tablet contains:
- Active ingredient: 100 mg imatinib (as imatinib mesylate). Imatinib mesylate is the salt form of imatinib that provides optimal bioavailability and stability. The molecular formula is C29H31N7O·CH4SO3 and the molecular weight is 589.7 g/mol.
Tablet core excipients (typical):
- Microcrystalline cellulose – bulking agent
- Crospovidone – disintegrant
- Hydroxypropyl cellulose – binder
- Colloidal anhydrous silica – flow agent
- Magnesium stearate – lubricant
Film coating (typical):
- Hypromellose – coating polymer
- Iron oxide yellow (E172) – colorant
- Iron oxide red (E172) – colorant
- Macrogol (polyethylene glycol) – plasticizer
- Talc – anti-adherent
The exact excipient list may vary slightly between generic formulations. Always consult the patient information leaflet supplied with your specific product for the complete list of ingredients. If you have a known allergy to any excipient, discuss this with your doctor or pharmacist before starting treatment.
Imatinib Zentiva 100 mg tablets are typically yellow to brownish-yellow, round, biconvex, film-coated tablets. The tablets may have a score line to facilitate splitting, though this should only be done if instructed by your healthcare provider. The tablets are available in blister packs of various sizes (typically 60 or 120 tablets per package), depending on the market.
Frequently Asked Questions About Imatinib Zentiva
Imatinib Zentiva is a tyrosine kinase inhibitor used to treat chronic myeloid leukemia (CML) in all phases, gastrointestinal stromal tumors (GIST), and several other cancers driven by specific molecular targets including PDGFR rearrangements, KIT mutations, and BCR-ABL. It is taken as a film-coated tablet, typically once or twice daily with food, and is prescribed by specialist oncologists or hematologists.
The most common side effects include nausea, vomiting, diarrhea, fluid retention (periorbital and peripheral edema), muscle cramps and musculoskeletal pain, skin rash, fatigue, and abdominal pain. Low blood counts (neutropenia, thrombocytopenia, anemia) are also very common and require regular monitoring. Most side effects are mild to moderate and manageable with appropriate supportive care and dose adjustments.
Imatinib has transformed CML from a life-threatening cancer to a manageable chronic condition for most patients. While it is not traditionally considered a “cure,” some patients who achieve sustained deep molecular responses may be eligible for treatment-free remission (TFR), where imatinib is discontinued under careful medical supervision. Long-term studies show 10-year overall survival rates exceeding 83% for patients treated with imatinib as first-line therapy.
Imatinib Zentiva is a generic version of imatinib, originally marketed by Novartis as Gleevec (in the United States) or Glivec (in Europe and other markets). It contains the same active ingredient (imatinib mesylate) at the same strength and has demonstrated bioequivalence to the originator product in regulatory studies. Generic imatinib products, including Imatinib Zentiva, must meet the same stringent quality, safety, and efficacy standards as the original brand.
Imatinib has significant drug interactions. CYP3A4 inhibitors (ketoconazole, itraconazole, clarithromycin, grapefruit juice) can increase imatinib levels and toxicity. CYP3A4 inducers (rifampicin, phenytoin, carbamazepine, St John’s Wort) can decrease imatinib levels and reduce treatment effectiveness. Imatinib also inhibits CYP3A4 and CYP2D6, which means it can increase levels of other drugs like warfarin, simvastatin, and ciclosporin. Always inform your doctor about all medications and supplements you take.
No, you should never stop taking imatinib without consulting your doctor, even if you feel well. For CML patients, stopping treatment prematurely can lead to disease relapse. Treatment-free remission (TFR) may be possible for some patients who have achieved a sustained deep molecular response, but this must only be attempted under careful medical supervision with regular molecular monitoring. Stopping imatinib outside of a structured TFR program puts you at risk of losing the treatment response that has been achieved.
References
- European Medicines Agency (EMA). Imatinib Zentiva – Summary of Product Characteristics. European Public Assessment Report (EPAR). Available at: ema.europa.eu. Last updated 2025.
- U.S. Food and Drug Administration (FDA). Gleevec (imatinib mesylate) Prescribing Information. FDA Drugs@FDA. Revised 2024.
- Hochhaus A, Larson RA, Guilhot F, et al. Long-Term Outcomes of Imatinib Treatment for Chronic Myeloid Leukemia. New England Journal of Medicine. 2017;376(10):917–927. doi:10.1056/NEJMoa1609324
- Demetri GD, von Mehren M, Blanke CD, et al. Efficacy and safety of imatinib mesylate in advanced gastrointestinal stromal tumors. New England Journal of Medicine. 2002;347(7):472–480. doi:10.1056/NEJMoa020461
- Druker BJ, Guilhot F, O’Brien SG, et al. Five-Year Follow-up of Patients Receiving Imatinib for Chronic Myeloid Leukemia. New England Journal of Medicine. 2006;355(23):2408–2417. doi:10.1056/NEJMoa062867
- World Health Organization. WHO Model List of Essential Medicines, 23rd List (2023). Geneva: WHO; 2023.
- Hochhaus A, Baccarani M, Silver RT, et al. European LeukemiaNet 2020 recommendations for treating chronic myeloid leukemia. Leukemia. 2020;34(4):966–984. doi:10.1038/s41375-020-0776-2
- National Comprehensive Cancer Network (NCCN). NCCN Clinical Practice Guidelines in Oncology: Chronic Myeloid Leukemia. Version 1.2025.
- Joensuu H, Eriksson M, Sundby Hall K, et al. One vs Three Years of Adjuvant Imatinib for Operable Gastrointestinal Stromal Tumor: A Randomized Trial. JAMA. 2012;307(12):1265–1272. doi:10.1001/jama.2012.347
- Mahon FX, Réa D, Guilhot J, et al. Discontinuation of imatinib in patients with chronic myeloid leukaemia who have maintained complete molecular remission for at least 2 years: the prospective, multicentre Stop Imatinib (STIM) trial. Lancet Oncology. 2010;11(11):1029–1035. doi:10.1016/S1470-2045(10)70233-3
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Medical Content
iMedic Medical Editorial Team – Specialists in Oncology, Hematology, and Clinical Pharmacology
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iMedic Medical Review Board – Independent panel following GRADE evidence framework
Sources
EMA SmPC, FDA Label, ESMO Guidelines, NCCN Guidelines, WHO Essential Medicines List
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All medical content is reviewed according to international evidence-based guidelines. Last reviewed: . Content is updated regularly to reflect the latest clinical evidence and regulatory information.