Imatinib interacts with several drugs. Strong CYP3A4 inhibitors such as ketoconazole, itraconazole, clarithromycin, and certain antivirals may increase Imatinib levels, while CYP3A4 inducers such as rifampin, phenytoin, carbamazepine, and dexamethasone may reduce its effectiveness. Grapefruit juice should be avoided as it increases plasma concentrations of Imatinib. Imatinib also increases the levels of CYP3A4 substrates like simvastatin, and caution should be taken with drugs that have a narrow therapeutic window. It has a weak inhibitory effect on CYP2D6 and may slightly increase metoprolol levels. Co-administration with warfarin should be avoided; low-molecular-weight or standard heparin is preferred. Caution is also required when combining Imatinib with acetaminophen, although no significant interaction has been observed at doses up to 400 mg/day.

The recommended dose of Imatinib varies by condition. For adults with Ph+ CML in chronic phase, the dose is 400 mg/day, while for accelerated phase or blast crisis, it is 600 mg/day. Pediatric patients with Ph+ CML chronic phase or Ph+ ALL are typically dosed at 340 mg/m²/day. Adults with Ph+ ALL require 600 mg/day. For MDS/MPD and metastatic or unresectable GIST, the dose is 400 mg/day. In DFSP, the recommended dose is 800 mg/day. Patients with aggressive systemic mastocytosis or HES/CEL may be treated with 100 mg/day or 400 mg/day, depending on response. Dose adjustments are necessary for patients with hepatic or renal impairment. Therapy should be initiated by an experienced physician, and tablets should be taken with a meal and a large glass of water.

There are no specific contraindications listed for Imatinib.

Very common side effects include weight gain due to water retention, headache, nausea, vomiting, diarrhea, indigestion, abdominal pain, skin rash, muscle cramps, musculoskeletal pain, and fatigue. Common side effects include loss of appetite, dizziness, altered taste, tingling or numbness, insomnia, conjunctivitis, blurred vision, dry eye, nosebleeds, abdominal swelling, constipation, gas, heartburn, dry mouth, itching, hair thinning, night sweats, weakness, hypersensitivity, joint swelling, abnormal liver tests, cough, fever, and swelling of the eyelids or face.

Imatinib can cause fetal harm and should not be used during pregnancy unless absolutely necessary. Women of childbearing potential should use effective contraception. There have been reports of spontaneous abortions and congenital anomalies associated with Imatinib. In nursing mothers, Imatinib and its metabolite are excreted into human milk, and infants may receive up to 10% of the maternal dose. Therefore, breastfeeding should be discontinued during treatment.

Precautions include monitoring for severe heart failure, serious bleeding, water retention, liver failure, and gastrointestinal perforation, which in rare cases can be fatal. Rhabdomyolysis has also been rarely observed. Patients should be carefully monitored for these risks during treatment.

Adult overdose with 1,200 to 1,600 mg for up to 10 days has caused nausea, vomiting, diarrhea, rash, edema, fatigue, pancytopenia, abdominal pain, and abnormal liver function tests. Doses as high as 3,200 mg daily have caused weakness, myalgia, elevated bilirubin, and gastrointestinal pain. Single doses of 6,400 mg and above have led to severe symptoms including facial swelling, pyrexia, and marked hematologic toxicity. Pediatric overdose cases have reported vomiting, diarrhea, anorexia, and low white blood cell counts.

Store Imatinib tablets at a temperature not exceeding 30°C, in a dry place, and protect them from light and moisture. Keep out of reach of children.