Irinotecan Sun (Irinotecan Hydrochloride Trihydrate)

• Irinotecan is used in oncology to target colorectal cancer pathways.
• Metastatic colorectal cancer: improves overall survival when incorporated into combination chemotherapy regimens.

• Irinotecan binds to the DNA‑topoisomerase I complex and stabilizes it, preventing the re‑ligation step of DNA replication. This inhibition leads to accumulation of single‑strand breaks, which are converted into lethal double‑strand breaks during replication, ultimately causing tumor cell apoptosis.

Irinotecan may cause a range of adverse reactions, varying from common to serious.

Common Side Effects

• Diarrhea: often severe and may require supportive care.
• Nausea and vomiting: typical chemotherapy‑related symptoms.
• Neutropenia: reduced white blood cell count increasing infection risk.
• Fatigue: general tiredness experienced during treatment.
• Alopecia: temporary hair loss.
• Anemia: decreased red blood cell levels.

Serious or Rare Side Effects

• Febrile neutropenia: fever with low neutrophil count, a medical emergency.
• Severe colitis or intestinal perforation: life‑threatening gastrointestinal complications.
• Hepatotoxicity: significant liver enzyme elevations.
• Severe allergic reactions: including anaphylaxis.
• Acute cholinergic syndrome: bradycardia, sweating, and bronchospasm.
• Tumor lysis syndrome: rapid tumor cell breakdown causing metabolic disturbances.

• When administering Irinotecan, clinicians should observe several safety measures.
• Monitor blood counts: perform regular CBC to detect neutropenia.
• Assess liver function: check hepatic enzymes before and during therapy.
• Evaluate gastrointestinal status: avoid use in patients with recent bowel surgery or obstruction.
• Check for hypersensitivity: discontinue if allergic reactions occur.
• Pregnancy and lactation: use only if potential benefits justify the risks to the fetus or infant.
• Store at 2-8°C: keep refrigerated, protect from light, do not freeze.

Irinotecan can interact with other medicines, affecting its safety or effectiveness.

Major Interactions (Avoid)

• UGT1A1 inhibitors (e.g., atazanavir): increase risk of severe neutropenia and diarrhea.
• Strong CYP3A4 inhibitors (e.g., ketoconazole): raise plasma concentrations, heightening toxicity.
• Concurrent abdominal radiotherapy: may exacerbate gastrointestinal toxicity.

Moderate Interactions (Monitor Closely)

• CYP3A4 inducers (e.g., rifampin): reduce drug exposure, potentially lowering efficacy.
• Anticholinergic agents: may worsen constipation and affect bowel motility.