Irinotecano Hikma (Irinotecan Hydrochloride Trihydrate)

Irinotecan is a topoisomerase I inhibitor used in the management of colorectal cancer.

• Metastatic colorectal cancer: used as a single agent or in combination regimens to achieve tumor shrinkage and prolong survival.
• Colorectal cancer refractory to fluoropyrimidine therapy: provides an alternative mechanism of action after failure of standard chemotherapy.
• Colorectal cancer in combination with 5‑fluorouracil and leucovorin (FOLFIRI): forms part of a standard regimen to enhance response rates.

• After intravenous administration, irinotecan is converted by hepatic carboxylesterases to the active metabolite SN‑38. SN‑38 binds to the DNA‑topoisomerase I complex, preventing the re‑ligation of single‑strand DNA breaks during replication. This inhibition leads to accumulation of DNA damage, triggering apoptosis in rapidly proliferating tumor cells, particularly those of colorectal origin.

Irinotecan may 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 and may require supportive care.
• Nausea and vomiting: typical chemotherapy‑related symptoms.
• Fatigue: generalized tiredness affecting daily activities.
• Alopecia: hair loss that is usually reversible.

Serious or Rare Side Effects

• Febrile neutropenia: fever with low neutrophil count requiring urgent treatment.
• Severe colitis or intestinal perforation: life‑threatening gastrointestinal complications.
• Hepatic toxicity: elevated liver enzymes or bilirubin.
• Allergic reactions: anaphylaxis or severe hypersensitivity.
• Pulmonary toxicity: interstitial lung disease or pneumonitis.

Before initiating therapy, clinicians should assess patient suitability and monitor for potential complications.

• Monitor blood counts: regular CBCs to detect neutropenia early.
• Assess liver function: baseline and periodic LFTs due to hepatic metabolism.
• Evaluate gastrointestinal status: avoid use in patients with active bowel obstruction.
• Avoid in patients with known hypersensitivity to irinotecan or its excipients.
• Adjust dose in renal or hepatic impairment: follow prescribing guidelines.
• Store at 2-8°C: keep refrigerated, protect from light, do not freeze or shake.

Irinotecan's efficacy and safety can be altered by concomitant medications.

Major Interactions (Avoid)

• Strong CYP3A4 inducers (e.g., rifampin): may reduce SN‑38 formation and therapeutic effect.
• Concurrent myelosuppressive agents: increase risk of severe neutropenia and infection.
• Potent UGT1A1 inhibitors: elevate SN‑38 levels, heightening toxicity.

Moderate Interactions (Monitor Closely)

• CYP3A4 inhibitors (e.g., ketoconazole): may increase irinotecan exposure.
• Anticholinergic drugs: can exacerbate diarrhea.
• Warfarin: may require INR monitoring due to potential interaction.