Mizantrone (Irinotecan Hydrochloride Trihydrate)

Mizantrone (irinotecan) is used in the management of colorectal cancer, targeting the topoisomerase I pathway.

• Colorectal cancer: improves overall survival when combined with fluoropyrimidine‑based regimens.
• Metastatic colorectal cancer: provides disease control in patients with advanced disease.
• Advanced colorectal cancer after first‑line therapy: offers an additional therapeutic option when disease progresses.

• Irinotecan is a pro‑drug that is converted intracellularly to SN‑38, a potent inhibitor of DNA topoisomerase I. By stabilizing the DNA‑topoisomerase I complex, it prevents the re‑ligation of single‑strand breaks during DNA replication, leading to accumulation of DNA damage and ultimately tumor cell death.

Mizantrone 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: may be severe and require supportive care.
• Nausea and vomiting: often managed with anti‑emetics.
• Alopecia: temporary hair loss.
• Fatigue: general tiredness and weakness.
• Abdominal pain: discomfort in the stomach area.

Serious or Rare Side Effects

• Febrile neutropenia: fever with low neutrophil count, a medical emergency.
• Severe diarrhea leading to dehydration or electrolyte imbalance.
• Intestinal perforation: rare but life‑threatening bowel rupture.
• Allergic reactions: including rash, bronchospasm, or anaphylaxis.
• Hepatotoxicity: elevated liver enzymes indicating liver injury.
• Severe mucositis: painful inflammation of the mouth and gastrointestinal lining.

Before initiating therapy with Mizantrone, clinicians should assess patient-specific factors and monitor for potential complications.

• Monitor blood counts: perform regular complete blood counts to detect neutropenia.
• Assess liver function: evaluate hepatic enzymes and bilirubin prior to each cycle.
• Evaluate bowel status: avoid use in patients with recent bowel obstruction or perforation.
• Dose adjustment: consider reduced dosing in patients with hepatic impairment.
• Hypersensitivity: discontinue if signs of an allergic reaction appear.
• Store at 2-8°C: keep refrigerated, protect from light, do not freeze or shake.

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

Major Interactions (Avoid)

• Strong CYP3A4 inducers (e.g., rifampin, carbamazepine): may reduce irinotecan exposure.
• Potent UGT1A1 inhibitors (e.g., atazanavir, indinavir): increase SN‑38 levels and toxicity.
• Concurrent myelosuppressive agents (e.g., cyclophosphamide): heighten risk of severe neutropenia.

Moderate Interactions (Monitor Closely)

• Moderate CYP3A4 inhibitors (e.g., fluconazole, erythromycin): may modestly increase exposure.
• Anticoagulants (e.g., warfarin): monitor INR as bleeding risk may rise.