Why It's Called the "FOLFIRI" Regimen

• FOL signifies Folinic Acid (Leucovorin), which is used to enhance the effectiveness of fluorouracil.

• FIRI stands for Fluorouracil (5-FU) and Irinotecan, the main chemotherapeutic agents in the regimen.

Purpose of the "FOLFIRI" Regimen

• Colorectal Cancer: Especially in patients with metastatic colorectal cancer as a first-line treatment or following disease progression after initial therapy.

• Other Cancers: Less commonly, it may be considered for other gastrointestinal cancers, as part of clinical trials or off-label use.

Key Components

1. Folinic Acid (Leucovorin):
• Class: Vitamin B9 analog
• Mechanism: Enhances the cytotoxic effects of fluorouracil by stabilizing the fluorouracil-thymidylate synthase complex.
• Administration: Intravenous infusion prior to fluorouracil.

2. Fluorouracil (5-FU):
• Class: Pyrimidine analog
• Mechanism: Inhibits thymidylate synthase, blocking DNA synthesis.
• Administration: Initially as a rapid intravenous bolus followed by a continuous infusion.

3. Irinotecan:
• Class: Topoisomerase inhibitor
• Mechanism: Inhibits topoisomerase I, leading to DNA damage and cell death.
• Administration: Intravenous infusion before fluorouracil and folinic acid.

Clinical Pearls

• Diarrhea Management: Irinotecan can cause severe, sometimes delayed diarrhea that requires immediate treatment with antidiarrheal medication (e.g., loperamide).

• Monitoring for Neutropenia: Regular blood counts are essential since both irinotecan and fluorouracil can cause myelosuppression.

• Infusion Reactions: Watch for signs of acute cholinergic symptoms during or shortly after irinotecan infusion; atropine may be required for symptomatic management.

• Hepatic Function: Adjust doses in patients with hepatic impairment especially since irinotecan metabolism is affected by liver function.

• Genetic Testing: Consider testing for UGT1A1 enzyme deficiency which can increase the risk of irinotecan toxicity.

Patient Management Tips

• Education on Side Effects: Ensure patients are well informed about potential side effects, particularly gastrointestinal symptoms, and understand when to seek help.

• Hydration and Nutrition: Advise on maintaining good nutrition and adequate hydration to manage side effects and support overall health.

• Emotional and Psychological Support: Address the psychological aspects of cancer treatment by referring patients to counselling or support groups.

• Skin Care: Provide guidance on managing skin reactions, a common side effect of fluorouracil.

• Drug Interactions: Carefully review all concurrent medications to manage potential interactions, particularly with drugs metabolized by the liver.