What are the side effects of Imatinib (Gleevec)?

Side Effects of Imatinib (Gleevec)

Imatinib has a generally good long-term safety profile, with most side effects being mild to moderate and manageable, though some serious adverse events may require dose adjustment or discontinuation.

Common Side Effects

• Fluid retention and edema are among the most frequent side effects, particularly periorbital edema (affecting up to 70% of patients) and peripheral edema 1, 2
• Gastrointestinal symptoms including diarrhea (59.3%), nausea (53.1%), vomiting (25.5%), and abdominal pain (21.1%) are very common 2
• Muscle cramps (38%) and musculoskeletal complaints including arthralgia (15.1%) and myalgia (12.2%) frequently affect quality of life 1, 2
• Skin rash occurs in approximately 26% of patients and is more frequent with higher doses, drugs with CYP3A4 interactions, dehydration, and sun exposure 1, 2
• Fatigue affects 57% of patients and can significantly impact daily activities 2

Hematological Toxicity

• Myelosuppression is among the most common adverse events with imatinib, though severe (grade 3-4) events are relatively uncommon 1
• Anemia occurs in approximately 47% of patients, though severe anemia is rare (0.6%) 2
• Neutropenia/granulocytopenia affects about 11.5% of patients, with grade 3-4 occurring in 3.1% 2
• Thrombocytopenia is less common but may require monitoring, especially during the first 3 months of treatment 1

Ocular Side Effects

• Periorbital edema is the most frequent ocular side effect, affecting up to 70% of patients 3
• Subconjunctival hemorrhage occurs in approximately 11% of patients, independent of cytopenias 3
• Epiphora (excessive eye watering) occurs in about 20% of patients due to conjunctival chemosis 3
• Loss of visual acuity should prompt immediate examination for more serious conditions like optic disc edema 3

Hepatic and Metabolic Effects

• Liver function test abnormalities occur in fewer than 5% of patients but require monitoring 1, 2
• Hyperglycemia affects approximately 9.8% of patients 2
• Hypocalcemia (5.6%) and hypokalemia (7.1%) may occur and should be monitored 2

Cardiovascular Effects

• Congestive heart failure is rare but serious, requiring careful monitoring in patients with pre-existing cardiac conditions 1, 4
• QT interval prolongation can occur, necessitating ECG monitoring, especially with higher doses or when combined with other QT-prolonging medications 1

Pulmonary Effects

• Pneumonitis is a rare but potentially serious complication that may require discontinuation of imatinib and administration of glucocorticoids 1
• Pleural effusions are very rare with imatinib compared to other TKIs like dasatinib 1

Management of Side Effects

• Mild to moderate skin reactions can be managed with topical therapies (lotions or glucocorticoids), systemic antihistamines, or short courses of systemic steroids 1
• Fluid retention is usually manageable with diuretics and rarely associated with cardiac dysfunction 1
• Gastrointestinal symptoms often improve with time and can be managed with supportive care; taking imatinib with food and a large glass of water may help reduce these effects 2
• Myelosuppression during the first 3 months of treatment should be managed with supportive care rather than dose reduction to maximize therapeutic response 1

Special Considerations

• Pregnancy: Women of reproductive potential should avoid becoming pregnant while taking imatinib and for fourteen days after stopping treatment 2
• Breastfeeding should be avoided during treatment and for 1 month after the last dose 2
• Drug interactions: Imatinib interacts with warfarin, erythromycin, phenytoin, and foods like grapefruit juice that inhibit CYP3A4 2
• Growth retardation has been reported in children and pre-adolescents receiving imatinib, requiring close monitoring 2

Monitoring Recommendations

• Regular blood count monitoring for myelosuppression 1
• Liver function tests to detect hepatotoxicity 2
• ECG monitoring for patients with risk factors for QT prolongation 1
• Regular ophthalmologic assessments for patients on long-term therapy 3

Most side effects of imatinib are manageable without dose reduction or interruption. However, severe toxicity may require individualized dose adjustment or switching to alternative TKIs 1.