Irinotecan Kabi (Irinotecan Hydrochloride Trihydrate)

• Irinotecan is a topoisomerase I inhibitor used in the management of colorectal cancer.
• Metastatic colorectal cancer: improves survival in patients with disease spread beyond the colon.
• Advanced colorectal cancer: provides disease control in patients with locally advanced disease.
• Colorectal cancer (first‑line therapy): used in combination with other agents for initial treatment of eligible patients.

• After intravenous infusion, irinotecan is converted intracellularly to its active metabolite SN‑38. SN‑38 binds to the DNA‑topoisomerase I complex and prevents the re‑ligation of single‑strand DNA breaks during replication, leading to accumulation of DNA damage and ultimately cancer cell death.

Irinotecan may cause a range of adverse reactions, which are categorized by frequency and severity.

Common Side Effects

• Neutropenia: reduced white blood cell count increasing infection risk.
• Diarrhea: may be severe and require supportive care.
• Nausea and vomiting: often managed with anti‑emetics.
• Fatigue: general tiredness experienced during treatment.
• Alopecia: hair loss that may be temporary.
• Anemia: decreased red blood cell count causing fatigue.

Serious or Rare Side Effects

• Febrile neutropenia: fever with low neutrophils requiring urgent medical attention.
• Severe colitis or intestinal perforation: life‑threatening gastrointestinal complications.
• Hepatotoxicity: liver enzyme elevations that may progress to liver injury.
• Severe allergic reactions: anaphylaxis or hypersensitivity requiring immediate treatment.
• Tumor lysis syndrome: rapid tumor cell breakdown causing metabolic disturbances.
• Cardiotoxicity: rare heart rhythm abnormalities.

• Before initiating therapy, clinicians should assess patient-specific factors and monitor for potential complications.
• Monitor blood counts: perform regular complete blood count tests to detect neutropenia.
• Assess liver function: evaluate hepatic enzymes as irinotecan metabolism is liver‑dependent.
• Evaluate bowel status: screen for pre‑existing diarrhea or intestinal obstruction.
• Adjust dose in hepatic impairment: reduce dosage for patients with significant liver dysfunction.
• Avoid use in known hypersensitivity: discontinue if severe allergic reaction occurs.
• Store at 2-8°C: keep refrigerated, protect from light, do not freeze or shake the vial.

Irinotecan can interact with other medicines, influencing its efficacy or toxicity.

Major Interactions (Avoid)

• Strong CYP3A4 inducers (e.g., rifampicin): may reduce SN‑38 formation and therapeutic effect.
• UGT1A1 inhibitors (e.g., atazanavir): can increase SN‑38 exposure and risk of severe neutropenia.
• Concurrent myelosuppressive agents: may cause additive bone‑marrow suppression.

Moderate Interactions (Monitor Closely)

• Anticoagulants (e.g., warfarin): monitor coagulation parameters due to potential bleeding risk.
• Drugs affecting gastrointestinal motility (e.g., loperamide): may alter diarrhea severity.
• Other chemotherapy agents (e.g., oxaliplatin): adjust dosing and monitor for overlapping toxicities.