Imatinib Mesylate is a proven kinase inhibitor belonging to the targeted therapy drug class. It is prescribed to treat a number of blood cancers. This formulation is marketed under the brand names Gleevec and Imarech. The drug is taken orally. It is one of the medicines on the WHO’s list of essential medicines.

FDA Approval History

• For Acute Lymphoblastic Leukemia: Jan 25, 2013
• For Rare Gastrointestinal Cancer: Jan 31, 2012

Uses

Imatinib Mesylate is a small molecule protein-tyrosine kinase inhibitor that is used in the treatment of patients with:

• Philadelphia chromosome-positive chronic myeloid leukemia (Ph+ CML).
• Philadelphia chromosome-positive chronic myeloid leukemia in blast crisis, accelerated phase, or in chronic phase following the failure of therapy with interferon-alpha.
• Refractory or relapsed Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL).
• Newly diagnosed Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) in combination with chemotherapy drugs.
• Myelodysplastic/myeloproliferative diseases related to PDGFR (platelet-derived growth factor receptor) gene rearrangements.
• Hypereosinophilic syndrome and/or chronic eosinophilic leukemia who possess the FIP1L1-PDGFRα fusion kinase.
• Unresectable, recurrent, and/or metastatic dermatofibrosarcoma protuberans.
• Gastrointestinal stromal tumors as an adjuvant treatment.

Working

This drug works by changing the function of multiple enzymes known as kinases. Imatinib Mesylate formulation works in the following manner.

• STEP-1
  Tyrosine Kinases: These are the enzymes that are responsible for transferring a phosphate group from ATP to the tyrosine residues of various proteins inside a cell. Tyrosine kinases are also known as the important mediators of the signaling cascade.
• STEP-2
  Imarech Enters: Imarech works to inhibit Bcr-Abl tyrosine kinase that is created by the Philadelphia chromosome abnormality in leukemia. It also inhibits cell proliferation.
• STEP-3
  Cell Death: Due to the inhibition of cell proliferation, apoptosis occurs in Bcr-Abl positive cell lines as well as fresh leukemic cells.

Side Effects

Like other targeted therapies, this medicine can have a few side effects too. That’s because the formulation is new to your body’s operations. The common and rare side effects related to Imatinib as listed below.

Common side effects

• Cough
• Chills
• Decreased appetite
• Bleeding gums
• Blood in the urine
• Clay-colored stools
• Diarrhea
• Ear congestion
• Chest pain
• Fever
• Seizures
• Shivering
• Pale skin
• Loss of voice
• Painful urination
• Mood changes
• Difficulty in sleeping
• Unusual weakness
• Yellowing of skin

Rare side effects

• Frequent vomiting
• Constipation
• Bone and joint pain
• Confusion
• Indigestion
• Redness of the eyes
• Delayed growth in toddlers
• Blurred vision
• Increased bowel movements
• Night sweats
• Lack of strength
• Muscle stiffness

Warnings and Precautions

• Pregnancy
  Females of child-bearing potential may not be prescribed this drug. That’s because of the increased risk of fetal harm to the baby. However, pregnant females were not included in human clinical trials.
• Nursing
  Clinicians aren’t sure whether this formulation gets excreted via breast milk. Imatinib Mesylate is not recommended for use in nursing patients due to the risk of adverse events in infants.
• Hematologic toxicity
  Conditions like neutropenia (a low white blood cell count) and anemia (a low red blood cell count) may occur during this therapy. To monitor the same, tests like complete blood count must be advised.
• Edema and fluid retention
  Due to the chance of fluid retention, the doctor weighs the patient regularly. Clinicians link edema with the use of Imatinib tablets.
• Heart problems
  Signs like rapid heartbeat, difficulty in breathing, persistent cough, stomach swelling, and fatigue may indicate an increased risk of congestive heart failure. Doctors thus advise regular monitoring of such signs during the therapy.
• Hepatotoxicity
  The use of this drug may lead to hepatotoxicity. It is a condition, also called toxic liver disease, that may cause some serious symptoms. Liver functions are, hence, necessary during the treatment period.
• Stomach-related problems
  In some patients, this medicine may cause gastrointestinal disorders. This is why clinicians ask the patients to take it with food. Drinking a large glass of water is recommended.

Interactions

Interactions between a drug and a disease or two drugs may result in complications. Such conditions can even decrease the efficacy of the medication.

• Interaction with medicines
  Formulations like brexpiprazole, adalimumab, fentanyl, deflazacort, leflunomide, zanubrutinib, phenytoin, neratinib, rifapentine, warfarin, and tofacitinib may cause moderate interactions with this drug. Certain other regimens may also influence the working of imatinib.
• Interaction with diseases
  Conditions including fluid retention, bone marrow suppression, and cardiovascular disease may interact with the functioning of this drug. Others like hepatic impairment, renal impairment, stomach disorders, and hypothyroidism can also have an impact.
• Interaction with food/alcohol
  Experts show that grapefruit can interact with imatinib and change its blood levels. Whereas orange juice may not cause any interactions.

Overdose

If Imatinib is taken more than the recommended dose, it may lead to complications. These may include unusual bleeding, stomach pain, blue fingernails, and swelling of the legs.

Recommended dose

• Ph+ chronic myelogenous leukemia: 400 mg/day in adult patients
• Ph+ chronic myelogenous leukemia: 340 mg/m2/day or 260 mg/m2/day in pediatric patients
• Ph+ acute lymphocytic leukemia: 600 mg/day in adult patients
• Myelodysplastic/myeloproliferative disorders: 400 mg/day in adult patients
• Hypereosinophilic syndrome: 100 mg/day or 400 mg/day in adult patients
• Dermatofibrosarcoma protuberans: 800 mg/day in adult patients
• Gastrointestinal stromal tumor: 400 mg/day in adult patients

Patients who can not swallow the tablets

The tablets should be dispersed in a glass of water or apple juice (approximately 50 mL for a 100 mg tablet).

NOTE: Taking this medicine without a prescription is not recommended. Kindly contact your medical team to learn more about the drug.