Irinotecan Aurobindo (Irinotecan Hydrochloride Trihydrate)

• Irinotecan is employed in the management of colorectal cancer, specifically targeting metastatic disease by interfering with DNA replication in rapidly dividing tumor cells.
• Metastatic colorectal cancer: when used in combination with fluoropyrimidine‑based regimens, it contributes to tumor shrinkage, prolongs progression‑free survival, and can improve overall survival in patients with advanced disease.
• Second‑line metastatic colorectal cancer after oxaliplatin‑based therapy: provides an alternative mechanism of action, offering disease control for patients whose tumors progressed on prior regimens.
• Combination with targeted agents (e.g., bevacizumab) in metastatic colorectal cancer: enhances therapeutic efficacy by adding cytotoxic activity to anti‑angiogenic treatment.

• Irinotecan is a prodrug converted intracellularly to SN‑38, a potent inhibitor of DNA topoisomerase I. By stabilizing the topoisomerase‑DNA cleavable complex, SN‑38 prevents relegation of single‑strand breaks, leading to accumulation of DNA damage, replication arrest, and ultimately apoptotic cell death in rapidly dividing tumor cells. The effect is cell‑cycle dependent, predominately affecting S‑phase cells, and the drug’s activity is enhanced by high expression of carboxylesterase enzymes that generate SN‑38 within the tumor microenvironment.

Irinotecan may cause a range of adverse reactions, varying in frequency and severity.

Common Side Effects

• Diarrhea: often severe and may require antidiarrheal treatment.
• Nausea and vomiting: typical chemotherapy‑related symptoms.
• Neutropenia: reduced white blood cell count increasing infection risk.
• Alopecia: hair loss during treatment.

Serious or Rare Side Effects

• Febrile neutropenia: fever with low neutrophils requiring urgent medical care.
• Severe colitis (including ileitis): inflammation of the colon that can be life‑threatening.
• Hypersensitivity reactions: rash, flushing, or anaphylaxis.

When using Irinotecan, careful monitoring and patient counseling are essential to mitigate risks.

• Dose adjustment: required for patients with hepatic impairment due to altered metabolism.
• Monitoring: regular blood counts and liver function tests are essential during therapy.
• Drug interactions: avoid concomitant use with strong CYP3A4 inhibitors that may increase SN‑38 exposure.
• Pregnancy and lactation: use only if potential benefit justifies risk; limited data available.
• Patient education: advise prompt reporting of severe diarrhea or fever.
• Store at 2-8°C: keep refrigerated, protect from light, do not freeze or shake.

Irinotecan interacts with several drug classes; awareness helps prevent toxicity.

Major Interactions (Avoid)

• Strong CYP3A4 inhibitors (e.g., ketoconazole, ritonavir): may markedly increase SN‑38 levels and toxicity.
• UGT1A1 inhibitors (e.g., atazanavir): can reduce SN‑38 clearance, raising risk of neutropenia.

Moderate Interactions (Monitor Closely)

• Anticoagulants (e.g., warfarin): increased bleeding risk due to mucosal damage.
• Other myelosuppressive agents (e.g., carboplatin): additive bone marrow suppression.
• Neurotoxic drugs (e.g., vincristine): potential enhanced neurotoxicity.