Irinotecano Basi (Irinotecan)

Irinotecan is a chemotherapy agent used primarily in the treatment of colorectal cancer and related disease stages.

• Metastatic colorectal cancer: administered in combination regimens to improve response rates and survival.
• Colorectal cancer (adjuvant): used after surgery as part of postoperative chemotherapy to reduce recurrence risk.
• Advanced solid tumours: occasionally incorporated in clinical protocols for refractory solid tumours where topoisomerase I inhibition is indicated.

• After intravenous infusion, irinotecan is converted by hepatic carboxylesterases to its active metabolite SN‑38. SN‑38 binds to the DNA‑topoisomerase I complex, preventing the religation of single‑strand DNA breaks during replication, which leads to accumulation of DNA damage and ultimately cancer cell death.

Irinotecan can cause 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, may require antidiarrheal therapy.
• Nausea and vomiting: typical chemotherapy‑related symptoms.
• Alopecia: hair loss during treatment cycles.
• Fatigue: generalized tiredness affecting daily activities.
• Anemia: decreased red blood cells causing weakness.

Serious or Rare Side Effects

• Febrile neutropenia: fever with low neutrophils, a medical emergency.
• Severe colitis or intestinal perforation from uncontrolled diarrhea.
• Hepatotoxicity: elevated liver enzymes or liver dysfunction.
• Hypersensitivity reactions: rash, bronchospasm, or anaphylaxis.
• Pulmonary toxicity: interstitial pneumonitis or fibrosis.

Before initiating irinotecan therapy, clinicians should assess patient‑specific risk factors and monitor relevant parameters.

• Hematologic monitoring: perform regular complete blood counts to detect neutropenia.
• Liver function: evaluate hepatic enzymes and bilirubin, adjusting dose if impaired.
• Gastrointestinal assessment: screen for bowel obstruction or inflammatory bowel disease.
• Concomitant myelosuppressants: use caution when combined with other bone‑marrow‑suppressing agents.
• Hypersensitivity: discontinue if signs of severe allergic reaction appear.
• Store at controlled room temperature: keep in original packaging, protect from moisture and light.

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

Major Interactions (Avoid)

• Strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole): increase SN‑38 exposure, raising toxicity risk.
• UGT1A1 inhibitors (e.g., atazanavir, indinavir): reduce SN‑38 clearance, leading to severe neutropenia.
• Concurrent high‑dose myelosuppressive chemotherapy: markedly heighten bone‑marrow suppression.

Moderate Interactions (Monitor Closely)

• CYP3A4 inducers (e.g., rifampin, carbamazepine): may lower drug levels, reducing effectiveness.
• Anticoagulants (e.g., warfarin): monitor coagulation parameters due to potential bleeding risk.
• Diuretics: watch for electrolyte disturbances that could exacerbate toxicity.