Irinotecan Hydrochloride Medac (Irinotecan Hydrochloride Trihydrate)

• Irinotecan is a topoisomerase I inhibitor used in the treatment of colorectal cancer and related metastatic disease.
• Metastatic colorectal cancer: improves survival when incorporated into combination chemotherapy regimens.
• Colorectal adenocarcinoma: reduces tumor progression in advanced disease settings.
• Colorectal cancer (adjuvant setting): used post‑surgery to lower recurrence risk in eligible patients.

• Irinotecan is a prodrug that is converted intracellularly to SN‑38, a potent inhibitor of topoisomerase I. By stabilizing the DNA‑topoisomerase I complex, SN‑38 prevents relegation of single‑strand DNA breaks, leading to accumulation of DNA damage, inhibition of DNA replication, and ultimately cancer cell death during the S‑phase of the cell cycle.

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

Common Side Effects

• Nausea and vomiting: mild to moderate gastrointestinal upset.
• Diarrhea: often early‑onset and may require antidiarrheal therapy.
• Neutropenia: reduced white blood cell count increasing infection risk.
• Fatigue: generalized tiredness during treatment cycles.
• Alopecia: temporary hair loss.
• Anorexia: decreased appetite.

Serious or Rare Side Effects

• Severe neutropenia or febrile neutropenia: requires immediate medical attention.
• Severe diarrhea or colitis: can lead to dehydration and electrolyte imbalance.
• Allergic reactions: rash, pruritus, or anaphylaxis in rare cases.
• Hepatic toxicity: elevated liver enzymes or jaundice.
• Pulmonary toxicity: interstitial pneumonitis or dyspnea.
• Hemorrhagic cystitis: rare urinary tract irritation.

• When using Irinotecan, clinicians should observe several safety measures to minimize risks.
• Monitor blood counts: perform regular CBC to detect neutropenia early.
• Assess liver function: adjust dosing in patients with hepatic impairment.
• Hydration: ensure adequate fluid intake to reduce risk of severe diarrhea.
• Pregnancy: avoid use unless potential benefits outweigh risks to the fetus.
• Drug‑specific monitoring: watch for signs of infection or severe gastrointestinal toxicity.
• Store at 2-8°C: keep refrigerated, protect from light, do not freeze or shake.

Irinotecan can affect or be affected by other medicines; awareness of key interactions helps manage therapy safely.

Major Interactions (Avoid)

• Strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole): may increase SN‑38 exposure and toxicity.
• Concurrent myelosuppressive agents (e.g., carboplatin, cyclophosphamide): heighten risk of severe neutropenia.
• Anticholinergic drugs (e.g., atropine) when used to manage diarrhea: may mask early signs of severe colitis.

Moderate Interactions (Monitor Closely)

• CYP3A4 inducers (e.g., rifampin, St. John’s wort): may reduce efficacy by lowering SN‑38 levels.
• Warfarin: Irinotecan may alter INR; monitor coagulation parameters.
• Other chemotherapeutic agents (e.g., 5‑FU, oxaliplatin): dose adjustments may be required based on combined toxicity profiles.