Imatinib Mesylate 100mg Tablets

Imatinib is a small molecule tyrosine kinase inhibitor. It selectively inhibits the Bcr-Abl tyrosine kinase, which is the oncogenic protein produced by the Philadelphia chromosome (Ph) in chronic myeloid leukemia (CML) and Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL). Imatinib also inhibits the receptor tyrosine kinases KIT (CD117) and PDGFRA (platelet-derived growth factor receptor alpha), which are implicated in the pathogenesis of gastrointestinal stromal tumors (GIST) and other diseases.

Urgent Side Effects: Seek Medical Help Right Away

While rare, some people may experience severe and potentially life-threatening side effects when taking this medication. If you notice any of the following symptoms, contact your doctor or seek medical attention immediately:

Signs of an allergic reaction: rash, hives, itching, red, swollen, blistered, or peeling skin with or without fever, wheezing, tightness in the chest or throat, trouble breathing, swallowing, or talking, unusual hoarseness, or swelling of the mouth, face, lips, tongue, or throat.
Signs of infection: fever, chills, severe sore throat, ear or sinus pain, cough, increased or changed sputum, painful urination, mouth sores, or a wound that won't heal.
Signs of bleeding: vomiting or coughing up blood, coffee ground-like vomit, blood in the urine, black, red, or tarry stools, bleeding gums, abnormal vaginal bleeding, unexplained bruises or bruises that get bigger, or uncontrollable bleeding.
Signs of electrolyte problems: mood changes, confusion, muscle pain, cramps, or spasms, weakness, shakiness, balance changes, abnormal heartbeat, seizures, loss of appetite, or severe nausea and vomiting.
Signs of kidney problems: inability to urinate, changes in urine output, blood in the urine, or significant weight gain.
Chest pain or pressure.
Abnormal burning, numbness, or tingling sensations.
Changes in vision, eye pain, or severe eye irritation.
Depression.
Bone pain.

Fluid Retention and Heart Failure

This medication may cause fluid retention, leading to swelling, weight gain, or breathing difficulties. If you experience any of these symptoms, inform your doctor. Additionally, if you have a history of heart disease, be aware that this medication may increase the risk of heart failure or worsen existing heart failure. Seek medical attention immediately if you experience:

Shortness of breath.
Significant weight gain.
Abnormal heartbeat.
New or worsening swelling in the arms or legs.

Liver Problems and Tumor Lysis Syndrome

Severe and potentially life-threatening liver problems may occur with this medication. If you notice any of the following symptoms, contact your doctor immediately:

Dark urine.
Fatigue.
Decreased appetite.
Nausea or stomach pain.
Light-colored stools.
Vomiting.
Yellow skin or eyes.

If you have cancer and are taking this medication, you may be at a higher risk of developing tumor lysis syndrome (TLS), a potentially life-threatening condition. Seek medical attention immediately if you experience:

Rapid or abnormal heartbeat.
Fainting.
Difficulty urinating.
Muscle weakness or cramps.
Nausea, vomiting, diarrhea, or loss of appetite.
Feeling sluggish.

Severe Skin Reactions

This medication may cause severe skin reactions, including Stevens-Johnson syndrome (SJS) and other serious conditions that can affect internal organs. These reactions can be life-threatening. Seek medical attention immediately if you experience:

Red, swollen, blistered, or peeling skin.
Red or irritated eyes.
Sores in the mouth, throat, nose, eyes, genitals, or skin.
Fever.
Chills.
Body aches.
Shortness of breath.
Swollen glands.

Other Side Effects

While many people may not experience side effects or may only have mild side effects, it's essential to be aware of the following:

Hair loss.
Muscle spasms.
Dizziness, drowsiness, fatigue, or weakness.
Sleep disturbances.
Gas.
Headache.
Dry skin.
Watery eyes.
Changes in taste.
Nose or throat irritation.
Back, muscle, joint, arm, or leg pain.
Weight gain.
Night sweats.
Anxiety.
Stomach pain or heartburn.
* Constipation, diarrhea, nausea, vomiting, or decreased appetite (common side effects that can be managed with your doctor's guidance).

If any of these side effects bother you, do not improve, or are severe, contact your doctor for advice.

Reporting Side Effects

If you have questions or concerns about side effects, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.

Before Taking This Medication: Important Information to Share with Your Doctor

It is essential to inform your doctor about the following:

Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the symptoms you experienced.
If you are taking warfarin, as this may interact with the medication.
If you are currently taking any of the following medications: carbamazepine, dexamethasone, phenobarbital, phenytoin, rifabutin, rifampin, or St. John's wort.
If you are breastfeeding or plan to breastfeed. Note that you should not breastfeed while taking this medication or for 1 month after your last dose.

This list is not exhaustive, and it is crucial to discuss all your medications, including prescription and over-the-counter drugs, natural products, and vitamins, with your doctor and pharmacist. They will help you determine if it is safe to take this medication with your existing medications and health conditions. Do not start, stop, or change the dose of any medication without first consulting your doctor.

It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication. Before engaging in activities that require alertness or clear vision, such as driving, wait until you understand how this drug affects you.

Regular blood tests and other laboratory assessments, as directed by your doctor, are crucial to monitor your condition. Additionally, avoid consuming grapefruit and grapefruit juice, as they may interact with this medication.

This drug may suppress the bone marrow's ability to produce necessary blood cells, potentially leading to bleeding problems, infections, or anemia if blood cell counts become severely low. If you have concerns, consult your doctor.

You may be more susceptible to infections; therefore, practice good hygiene by washing your hands frequently and avoiding close contact with individuals who have infections, colds, or flu.

Be cautious, as this medication may increase your risk of bleeding easily. To minimize this risk, use a soft toothbrush, an electric razor, and avoid injuries. If you have had your thyroid removed, discuss with your doctor the need for more frequent blood tests.

Before receiving any vaccinations, consult your doctor, as some vaccines may not be effective or may increase the risk of infection when used with this medication.

You may be more prone to sunburn; thus, limit your exposure to the sun, sunlamps, and tanning beds, and use protective measures such as sunscreen, clothing, and eyewear.

Rare but potentially life-threatening gastrointestinal tract perforations have been associated with this drug. Discuss any concerns with your doctor.

If you are 65 years or older, use this medication with caution, as you may be more likely to experience side effects.

In some cases, this drug may affect growth in children and teenagers, necessitating regular growth checks. Consult your doctor to discuss this potential risk.

This medication may harm an unborn baby. A pregnancy test will be conducted before initiating treatment to confirm that you are not pregnant. If you may become pregnant, use birth control while taking this drug and for at least 2 weeks after your last dose. If you become pregnant, notify your doctor immediately.

• Not explicitly contraindicated with specific drugs, but co-administration with strong CYP3A4 inducers is generally avoided due to significant reduction in imatinib levels.

• Strong CYP3A4 inducers (e.g., Rifampin, Phenytoin, Carbamazepine, Phenobarbital, St. John's Wort): May significantly decrease imatinib plasma concentrations, leading to loss of efficacy.
• Warfarin: Imatinib may increase warfarin concentrations and enhance anticoagulant effect, increasing bleeding risk.
• CYP3A4 substrates with narrow therapeutic index (e.g., Cyclosporine, Tacrolimus, Sirolimus, Fentanyl, Alfentanil, Ergot alkaloids, Pimozide, Quinidine, Dihydroergotamine): Imatinib may increase their plasma concentrations.

• Strong CYP3A4 inhibitors (e.g., Ketoconazole, Itraconazole, Clarithromycin, Erythromycin, Ritonavir, Indinavir, Grapefruit juice): May increase imatinib plasma concentrations, increasing risk of adverse effects.
• Midazolam (CYP3A4 substrate): Imatinib increases midazolam AUC.
• Simvastatin (CYP3A4 substrate): Imatinib increases simvastatin Cmax and AUC.
• Metoprolol (CYP2D6 substrate): Imatinib may increase metoprolol concentrations.
• Paracetamol/Acetaminophen: Potential for increased hepatotoxicity when co-administered with imatinib, especially with high doses of paracetamol.

• Not specifically categorized as minor, but caution with any drug metabolized by CYP3A4, CYP2D6, CYP2C9, CYP2C19.

• Fever, chills, sore throat (signs of infection/neutropenia)
• Unusual bleeding or bruising (signs of thrombocytopenia)
• Fatigue, pallor, shortness of breath (signs of anemia)
• Yellowing of skin or eyes, dark urine, abdominal pain (signs of hepatotoxicity)
• Swelling (especially around eyes, ankles, hands), sudden weight gain, shortness of breath, cough (signs of fluid retention/edema)
• Muscle cramps or spasms
• Skin rash
• Nausea, vomiting, diarrhea, abdominal pain
• Headache
• Muscle pain, joint pain

Imatinib is classified as Pregnancy Category D. It can cause fetal harm when administered to a pregnant woman. Based on animal studies and its mechanism of action, imatinib is expected to cause serious birth defects. Avoid use during pregnancy. Women of childbearing potential should be advised to use effective contraception during treatment and for at least 14 days after the last dose.

Imatinib and its active metabolite are excreted into human milk. Due to the potential for serious adverse reactions in breastfed infants, breastfeeding is not recommended during treatment with imatinib and for at least 14 days after the last dose.

Imatinib is approved for pediatric patients with Ph+ CML (chronic phase) and Ph+ ALL. Dosing is typically based on body surface area (BSA). Long-term effects on growth and development should be monitored. Cases of growth retardation have been reported in children and pre-pubertal adolescents.

No specific dose adjustment is required based on age alone. However, elderly patients may be more susceptible to certain adverse effects, such as fluid retention and myelosuppression. Monitor closely for adverse reactions.

• Imatinib should always be taken with food and a large glass of water to minimize gastrointestinal irritation and improve absorption.
• Fluid retention (edema, pleural effusion, ascites) is a common and potentially serious side effect; monitor weight and fluid status regularly. Diuretics may be needed.
• Myelosuppression (neutropenia, thrombocytopenia, anemia) is dose-limiting; regular CBC monitoring is crucial, and dose adjustments may be necessary.
• Hepatotoxicity can occur; monitor LFTs closely, especially during the first few months of therapy.
• Patients should be educated on the importance of adherence to therapy for optimal outcomes in CML and GIST.
• For patients with difficulty swallowing, the tablets can be dispersed in a glass of water or apple juice (for 100mg tablets, 50mL; for 400mg tablets, 200mL). Stir until completely dispersed and drink immediately. Do not crush or cut tablets if pregnant or planning pregnancy due to potential exposure.
• Resistance to imatinib can develop, necessitating monitoring of molecular and cytogenetic responses (BCR-ABL levels, Ph chromosome) to guide therapy changes.

• Other BCR-ABL tyrosine kinase inhibitors (for CML/Ph+ ALL): Dasatinib, Nilotinib, Bosutinib, Ponatinib (for resistant/intolerant cases).
• Chemotherapy (e.g., for ALL, or prior to TKI era for CML).
• Allogeneic hematopoietic stem cell transplantation (HSCT) (for CML, especially in advanced phases or TKI failure).
• Surgical resection (for localized GIST).
• Other targeted therapies or chemotherapy regimens depending on specific cancer type and stage.

If your symptoms or health issues persist or worsen, it's essential to contact your doctor for further guidance. To ensure your safety, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so be sure to check with your pharmacist for more information. If you have any questions or concerns about this medication, don't hesitate to reach out to your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek medical attention. When seeking help, be prepared to provide details about the medication, including the amount taken and the time it happened, to ensure you receive the best possible care.