Irinotecan Sun (Irinotecan Hydrochloride Trihydrate)

Irinotecan Sun belongs to the topoisomerase I inhibitor class and is used in colorectal cancer therapy.

• Metastatic colorectal cancer: improves overall survival when combined with fluoropyrimidine‑based chemotherapy.

• Irinotecan is converted intracellularly to its active metabolite SN‑38, which binds to the DNA‑topoisomerase I complex and prevents the religation step of single‑strand DNA breaks. This inhibition leads to accumulation of DNA damage, replication fork collapse, and ultimately tumor cell apoptosis.

Irinotecan may cause a range of adverse reactions, from mild to severe.

Common Side Effects

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

Serious or Rare Side Effects

• Febrile neutropenia: fever with low neutrophils requiring urgent treatment.
• Severe colitis or intestinal perforation.
• Hepatic toxicity: elevated liver enzymes or jaundice.
• Hypersensitivity reactions: rash, bronchospasm, or anaphylaxis.
• Severe abdominal pain or cramping.
• Thromboembolic events: rare clot formation.

Prior to 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: check hepatic enzymes before and during treatment.
• Evaluate bowel status: avoid use in patients with recent abdominal surgery or obstruction.
• Dose adjustment: consider reduced dosing in patients with hepatic impairment.
• Avoid in known hypersensitivity: discontinue if severe allergic reaction occurs.
• Store at 2-8°C: keep refrigerated, protect from light, do not freeze or shake.

Irinotecan can interact with several drug classes, influencing efficacy or toxicity.

Major Interactions (Avoid)

• Strong CYP3A4 inducers (e.g., rifampin, carbamazepine): may reduce irinotecan exposure.
• UGT1A1 inhibitors (e.g., atazanavir, indinavir): increase SN‑38 levels and risk of neutropenia.
• Concurrent myelosuppressive agents: amplify bone‑marrow suppression.

Moderate Interactions (Monitor Closely)

• Anticholinergic drugs: may exacerbate diarrhea.
• Warfarin: monitor INR as hepatic effects can alter coagulation.
• Other hepatotoxic medications: increase risk of liver injury.
• Proton pump inhibitors: potential impact on drug absorption.
• Herbal supplements affecting CYP enzymes: assess for possible interaction.