Irinotecan

Definition

Irinotecan is a chemotherapy drug used primarily in the treatment of colorectal cancer. It functions as a topoisomerase I inhibitor, interfering with the DNA replication process and ultimately leading to cancer cell death. This drug is often used in combination with other medications to enhance its effectiveness and manage various cancer types.

5 Must Know Facts For Your Next Test

1. Irinotecan is administered intravenously and can be given alone or in combination with drugs like fluorouracil and leucovorin for better outcomes.
2. The drug is metabolized in the liver to its active form, SN-38, which has a much stronger inhibitory effect on topoisomerase I than irinotecan itself.
3. Common side effects of irinotecan include diarrhea, nausea, vomiting, and myelosuppression, which can lead to a decrease in blood cell counts.
4. Patients receiving irinotecan may experience variations in drug response due to genetic differences in drug metabolism enzymes, particularly UGT1A1.
5. Irinotecan has been associated with a specific dose-limiting toxicity called 'early-onset diarrhea,' which occurs within 24 hours after administration and requires prompt treatment.

Review Questions

• How does irinotecan affect DNA replication in cancer cells, and what is the role of topoisomerase I in this process?
  • Irinotecan acts by inhibiting topoisomerase I, an enzyme that is essential for DNA replication. When topoisomerase I creates single-strand breaks in DNA to relieve torsional stress during replication, irinotecan prevents the re-ligation of these breaks, leading to DNA damage. This ultimately triggers apoptosis in cancer cells, contributing to its effectiveness as a chemotherapy agent specifically targeting rapidly dividing cells like those found in tumors.
• Discuss the importance of understanding genetic variations in patients when administering irinotecan therapy.
  • Understanding genetic variations is crucial when administering irinotecan because these differences can significantly affect how the drug is metabolized. For instance, patients with certain polymorphisms in the UGT1A1 gene may experience severe toxicity due to reduced metabolism of SN-38, the active metabolite of irinotecan. Identifying these genetic variations allows healthcare providers to tailor dosing regimens and prevent adverse effects, improving patient outcomes while minimizing risks.
• Evaluate the impact of irinotecan's side effects on patient quality of life during cancer treatment and potential management strategies.
  • The side effects of irinotecan, particularly diarrhea and myelosuppression, can substantially impact a patient's quality of life during treatment. Early-onset diarrhea can lead to dehydration and hospitalization if not managed properly. To mitigate these side effects, proactive measures such as administering anti-diarrheal medications like loperamide, ensuring proper hydration, and closely monitoring blood cell counts are essential. By implementing effective management strategies, healthcare providers can help maintain patients' overall well-being while undergoing chemotherapy.

Related terms

Topoisomerase I: An enzyme that alters the supercoiled form of DNA by creating transient single-strand breaks, which is crucial for DNA replication and transcription.

Camptothecin: A natural alkaloid derived from the Camptotheca acuminata tree, which served as the basis for the development of irinotecan and other topoisomerase inhibitors.

Colorectal Cancer: A type of cancer that starts in the colon or rectum, often treated with chemotherapy, targeted therapy, and surgery.