Irinotecan Hikma (Irinotecan Hydrochloride Trihydrate)

• Irinotecan is a topoisomerase I inhibitor that forms a core component of chemotherapy protocols for colorectal cancer, addressing disease progression and tumor burden.
• Metastatic colorectal cancer: improves overall survival and disease control when used in combination chemotherapy regimens.
• Colorectal adenocarcinoma (advanced): contributes to tumor shrinkage as part of FOLFIRI or similar protocols.
• Colorectal cancer after oxaliplatin failure: used as a second‑line option to target resistant disease.

• Irinotecan is a pro‑drug that is converted intracellularly to its active metabolite SN‑38. SN‑38 binds to the DNA‑topoisomerase I complex, stabilizing it and preventing the re‑ligation of single‑strand DNA breaks generated during replication. This inhibition leads to accumulation of DNA damage, triggering apoptosis in rapidly proliferating tumor cells, particularly those of colorectal origin. The drug’s effect is enhanced in cells with deficient DNA repair pathways, contributing to its selective cytotoxicity.

Irinotecan may cause a range of adverse reactions that vary in frequency and severity.

Common Side Effects

• Diarrhea: often severe and may require antidiarrheal therapy.
• Neutropenia: reduced white‑blood‑cell count increasing infection risk.
• Nausea and vomiting: may be managed with antiemetics.
• Alopecia: hair loss that is usually reversible.
• Fatigue: generalized tiredness during treatment.
• Anemia: decreased red‑blood‑cell levels.

Serious or Rare Side Effects

• Febrile neutropenia: fever with low neutrophil count requiring urgent care.
• Severe colitis or bowel perforation due to intense diarrhea.
• Cholinergic syndrome: abdominal cramping, sweating, and bradycardia.
• Hypersensitivity reactions: rash, bronchospasm, or anaphylaxis.
• Hepatotoxicity: elevated liver enzymes or liver dysfunction.

Prior to initiating therapy, clinicians should evaluate patient‑specific factors and monitor for potential complications.

• Monitor blood counts: perform regular complete blood count tests to detect neutropenia or anemia.
• Assess liver function: check hepatic enzymes and bilirubin before each cycle.
• Evaluate gastrointestinal status: avoid use in patients with recent bowel obstruction or inflammatory bowel disease.
• Adjust dose in renal impairment: consider reduced dosing for patients with compromised kidney function.
• Avoid in known hypersensitivity: discontinue if severe allergic reactions occur.
• Store at 2-8°C: keep refrigerated, protect from light, do not freeze.

Irinotecan can interact with other medicines, altering its efficacy or safety profile.

Major Interactions (Avoid)

• Strong CYP3A4 inducers (e.g., rifampin, carbamazepine): may reduce irinotecan exposure.
• UGT1A1 inhibitors (e.g., atazanavir, indinavir): can increase SN‑38 levels and toxicity.
• Concurrent myelosuppressive agents: heighten risk of severe neutropenia and anemia.

Moderate Interactions (Monitor Closely)

• Anticoagulants (warfarin, DOACs): increased bleeding risk due to mucosal injury.
• Other antineoplastic drugs (e.g., oxaliplatin): may augment cumulative hematologic toxicity.
• Drugs affecting electrolyte balance (e.g., diuretics): monitor for dehydration from diarrhea.