Irinotecano Farmoz (Irinotecan Hydrochloride Trihydrate)

Irinotecan is used in chemotherapy regimens targeting colorectal cancer and other solid tumours.

• Colorectal cancer: improves response rates and overall survival when combined with fluoropyrimidine‑based regimens.
• Gastric cancer: used in combination protocols to enhance tumour control.
• Pancreatic cancer: incorporated into multi‑agent regimens for disease management.
• Non‑small cell lung cancer: added to standard chemotherapy to increase efficacy.

• Irinotecan is a pro‑drug that is converted intracellularly to SN‑38, a potent inhibitor of topoisomerase I. By stabilising the transient DNA‑topoisomerase I complex, SN‑38 prevents relegation of single‑strand breaks, leading to accumulation of DNA damage and inhibition of replication in rapidly dividing cancer cells. The active metabolite is primarily eliminated by hepatic glucuronidation via UGT1A1, and its cytotoxic effect is most pronounced during the S‑phase of the cell cycle.

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

Common Side Effects

• Neutropenia: reduced white blood cell count leading to infection risk.
• Diarrhea: frequent loose stools that may require supportive care.
• Nausea and vomiting: gastrointestinal upset commonly observed during treatment.

Serious or Rare Side Effects

• Febrile neutropenia: fever with low neutrophils requiring urgent medical attention.
• Severe colitis (ileocolitis): intense abdominal pain and bloody diarrhea.
• Allergic reactions: rash, bronchospasm or anaphylaxis in susceptible patients.

Before initiating Irinotecano Farmoz, clinicians should observe several precautionary measures to minimise toxicity.

• Monitor blood counts: perform regular complete blood count assessments to detect neutropenia early.
• Assess liver function: evaluate hepatic enzymes because impaired metabolism increases SN‑38 exposure.
• Evaluate bowel health: screen for pre‑existing diarrhoea or intestinal obstruction before treatment.
• Adjust dose in hepatic or renal impairment: consider reduced dosing in patients with significant organ 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.

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

Major Interactions (Avoid)

• Strong CYP3A4 inducers (e.g., rifampin, carbamazepine): may markedly reduce SN‑38 levels and therapeutic effect.
• UGT1A1 inhibitors (e.g., atazanavir, indinavir): increase SN‑38 exposure and risk of severe neutropenia or diarrhea.
• Concurrent myelosuppressive agents (e.g., high‑dose cyclophosphamide): can exacerbate bone‑marrow suppression.

Moderate Interactions (Monitor Closely)

• Anticoagulants (e.g., warfarin): enhanced bleeding risk due to potential liver enzyme interactions.
• Antidiarrheal agents (e.g., loperamide): may mask early signs of irinotecan‑induced diarrhea.
• Other topoisomerase inhibitors: additive toxicity may require dose adjustments.