DOSE AND DOSAGE
- Adults: The typical dose of imatinib for adults with chronic myeloid leukemia (CML) or gastrointestinal stromal tumors (GIST) is 400 mg orally once daily.
- Pediatric Patients: For pediatric patients with Ph-positive chronic phase CML or pediatric patients with GIST, the recommended dose is based on body surface area and ranges from 260 mg/m^2 to 340 mg/m^2 once daily.
- Doses may need adjustment based on individual patient factors and response to treatment.
FREQUENCY
- Generally, imatinib is taken once daily.
ROUTE OF ADMINISTRATION (ROA)
- Imatinib is administered orally as a tablet formulation.
MECHANISM OF ACTION (MOA)
- Imatinib is a tyrosine kinase inhibitor that selectively targets specific protein kinases, including BCR-ABL, c-kit, and PDGF-R, which are implicated in the pathogenesis of CML and GIST. By inhibiting these kinases, imatinib disrupts cell signaling pathways involved in tumor growth and survival.
PHARMACOKINETICS (PK)
- Absorption: Imatinib is well-absorbed after oral administration, with peak plasma concentrations reached within 2 to 4 hours.
- Distribution: It is extensively distributed throughout the body, including penetration into the central nervous system.
- Metabolism: Imatinib undergoes extensive hepatic metabolism primarily by CYP3A4 and CYP3A5 enzymes.
- Elimination: The major route of elimination is via the feces, with a smaller proportion excreted in the urine.
PATHOPHYSIOLOGY
- Imatinib targets specific molecular pathways involved in the pathogenesis of CML, GIST, and other malignancies, disrupting abnormal signaling cascades that promote cell proliferation, survival, and differentiation.
INDICATIONS
- Imatinib is indicated for the treatment of:
- Chronic myeloid leukemia (CML) in adults and pediatric patients in chronic phase, accelerated phase, or blast crisis.
- Gastrointestinal stromal tumors (GIST) in adult patients after disease progression on or intolerance to prior treatment with other agents.
- Dermatofibrosarcoma protuberans (DFSP) in adult patients who are not eligible for surgical resection, as well as adjuvant treatment of adult patients following surgical resection.
- Hypereosinophilic syndrome (HES) and/or chronic eosinophilic leukemia (CEL) with FIP1L1-PDGFRα fusion kinase-positive disease in adult and pediatric patients.
CONTRAINDICATIONS
- Known hypersensitivity to imatinib or any component of the formulation.
DRUG INTERACTIONS
- Imatinib metabolism may be affected by concomitant administration of strong CYP3A4 inhibitors or inducers, potentially altering imatinib plasma concentrations.
- Avoid concurrent use of drugs that prolong the QT interval or are substrates of CYP3A4, as imatinib may increase their plasma concentrations.
PRECAUTIONS
- Hepatotoxicity: Monitor liver function tests periodically during treatment.
- Myelosuppression: Regularly monitor complete blood counts for cytopenias, particularly in the initial phases of treatment.
- Fluid Retention and Edema: Monitor for signs and symptoms of fluid retention, including peripheral edema, and manage appropriately.
- Cardiovascular Events: Imatinib may increase the risk of cardiovascular events, particularly in patients with pre-existing cardiovascular disease.
- Renal Impairment: Use caution and adjust the dose in patients with renal impairment.
- Pregnancy and Lactation: Imatinib may cause fetal harm if used during pregnancy. Advise women of reproductive potential to use effective contraception during treatment and for a period after discontinuation. Additionally, breastfeeding is not recommended during treatment with imatinib.
Medication Information and Guidelines
| Question | Answer |
|---|---|
| What’s the purpose of taking this medication? | Imatinib is used to treat certain types of cancer, including chronic myeloid leukemia (CML), gastrointestinal stromal tumors (GIST), and other malignancies. |
| How is one supposed to use this medicine? | Imatinib is typically taken orally as directed by a healthcare professional, usually once daily with a meal and a full glass of water. |
| Are there other reasons people might use this medication? | Occasionally, imatinib may be used off-label for conditions other than cancer, but this should only be done under the guidance of a healthcare provider. |
| Are there any specific things one needs to be careful about? | Individuals taking imatinib should be monitored for liver function, blood counts, fluid retention, and cardiac function regularly during treatment. |
| Do one need to make any changes to diet? | There are no specific dietary restrictions associated with imatinib use. However, maintaining a healthy diet and staying hydrated is generally recommended. |
| What should one do if he/she forgets a dose? | If a dose of imatinib is missed, it should be taken as soon as remembered, unless it is closer to the time of the next dose. In that case, the missed dose should be skipped. |
| What are the possible side effects? | Common side effects of imatinib may include nausea, vomiting, diarrhea, fluid retention, fatigue, rash, and muscle cramps. More serious side effects are possible and should be reported to a healthcare provider. |
| How should one store and dispose of this medication? | Imatinib tablets should be stored at room temperature away from moisture and heat. Unused or expired medication should be disposed of properly according to local regulations. |
| What should one do in case of an overdose or emergency? | In case of an overdose or emergency situation, medical attention should be sought immediately. Additionally, regular monitoring and laboratory tests may be necessary to assess treatment response and detect any potential adverse effects. |