Irinotecan Sun (Irinotecan Hydrochloride Trihydrate)

• Irinotecan is a topoisomerase I inhibitor used in colorectal cancer therapy.
• Metastatic colorectal cancer: improves overall survival when combined with fluoropyrimidine‑based regimens.
• Advanced colorectal cancer: provides disease control in patients who have progressed after prior therapy.
• Colorectal cancer (in combination therapy): enhances response rates when used with other chemotherapeutic agents.

• After intravenous infusion, irinotecan is converted by hepatic carboxylesterases to the active metabolite SN‑38. SN‑38 binds to the DNA‑topoisomerase I complex, stabilizing it and preventing relegation of single‑strand breaks. This results in accumulation of DNA damage, inhibition of DNA replication, and ultimately cancer cell death.

Irinotecan is associated with a range of adverse reactions that vary in frequency and severity.

Common Side Effects

• Neutropenia: reduced white blood cell count increasing infection risk.
• Diarrhea: often severe and may require antidiarrheal therapy.
• Nausea and vomiting: typical chemotherapy‑related symptoms.
• Fatigue: generalized tiredness affecting daily activities.
• Alopecia: hair loss that is usually reversible.
• Anemia: decreased red blood cell count causing fatigue.

Serious or Rare Side Effects

• Febrile neutropenia: fever with low neutrophils requiring urgent care.
• Severe colitis: life‑threatening inflammation of the colon.
• Hepatic toxicity: elevated liver enzymes or jaundice.
• Severe allergic reactions: anaphylaxis or hypersensitivity.
• Stomatitis: painful inflammation of the mouth lining.
• Cardiotoxicity: rare cardiac events such as arrhythmias.

• Before initiating therapy, clinicians should evaluate patient‑specific risk factors and monitor for toxicity.
• Monitor blood counts: perform regular CBC to detect neutropenia.
• Assess liver function: adjust dosing in hepatic impairment.
• Hydration: maintain adequate fluid intake to reduce risk of severe diarrhea.
• Avoid concurrent myelosuppressive agents unless clinically necessary.
• Pregnancy and lactation: contraindicated unless benefits outweigh risks.
• Store at 2-8°C: keep refrigerated, protect from light, do not freeze or shake.

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

Major Interactions (Avoid)

• UGT1A1 inhibitors (e.g., atazanavir): increase SN‑38 exposure – avoid.
• Strong CYP3A4 inducers (e.g., rifampin): reduce efficacy – avoid.
• Concurrent myelosuppressive chemotherapy: heightened bone‑marrow toxicity – avoid.

Moderate Interactions (Monitor Closely)

• Antiemetics (e.g., ondansetron): may affect metabolism – monitor.
• Warfarin: potential increased bleeding – monitor INR.
• Fluoropyrimidines (e.g., 5‑FU): additive gastrointestinal toxicity – monitor.