Irinotecan Eugia (Irinotecan Hydrochloride Trihydrate)

Irinotecan is used in colorectal cancer therapy, targeting tumor cells that rely on topoisomerase I activity.

• Metastatic colorectal cancer: improves survival when combined with fluoropyrimidine‑based regimens.
• Advanced colorectal carcinoma: provides therapeutic benefit after failure of first‑line treatment.
• Colorectal adenocarcinoma: used as part of combination chemotherapy protocols.

• Irinotecan is a pro‑drug that is converted intracellularly to SN‑38, a potent inhibitor of topoisomerase I. By stabilizing the transient DNA‑topoisomerase I complex, SN‑38 prevents relegation of single‑strand breaks, leading to accumulation of DNA damage and inhibition of DNA replication in rapidly dividing cancer cells. The drug preferentially accumulates in tumor tissue due to enhanced permeability and retention, and its activity is further modulated by hepatic enzymes such as CYP3A4 and UGT1A1, which affect conversion to SN‑38 and clearance.

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

Common Side Effects

• Nausea: mild to moderate nausea often occurring during infusion.
• Diarrhea: acute diarrhea that may require antidiarrheal therapy.
• Neutropenia: reduced neutrophil count increasing infection risk.
• Fatigue: generalized tiredness affecting daily activities.
• Alopecia: hair loss that is usually reversible after treatment.

Serious or Rare Side Effects

• Severe neutropenia with fever: febrile neutropenia requiring hospitalization.
• Grade 3–4 diarrhea: may lead to dehydration and colitis.
• Hepatic toxicity: elevated liver enzymes or bilirubin.
• Allergic reactions: rash, pruritus, or anaphylaxis.
• Severe abdominal pain: may indicate intestinal perforation.

Prior to initiating Irinotecan therapy, several safety considerations should be evaluated.

• Monitor blood counts: perform baseline and periodic CBC to detect neutropenia.
• Assess liver function: evaluate hepatic enzymes and bilirubin, adjust dose if impaired.
• Ensure adequate hydration: maintain fluid intake to mitigate diarrhea risk.
• Review concomitant medications: avoid strong CYP3A4 inhibitors that may increase exposure.
• Pregnancy and lactation: use only if potential benefit justifies potential risk to fetus or infant.
• Store at 2-8°C: keep refrigerated, protect from light, do not freeze.

Irinotecan interacts with several drugs that can alter its efficacy or toxicity.

Major Interactions (Avoid)

• Ketoconazole: potent CYP3A4 inhibitor that can raise irinotecan plasma levels.
• Rifampin: strong CYP3A4 inducer that may reduce therapeutic exposure.
• Atazanavir: UGT1A1 inhibitor increasing SN‑38 concentrations and toxicity.

Moderate Interactions (Monitor Closely)

• Warfarin: may experience altered anticoagulant effect; monitor INR.
• Loperamide: can mask early signs of irinotecan‑induced diarrhea.
• Anticholinergic agents: may exacerbate constipation and affect gastrointestinal motility.