Irinotecan

Irinotecan inhibits topoisomerase-1 which catalyses the breaking and rejoining of DNA strands.

Irinotecan is licensed for first-line use in patients with advanced colorectal cancer, in combination with fluorouracil and folinic acid, and as second-line monotherapy when fluorouracil-based therapy has failed (1)

A regime of 5-fluorouracil and leucovirin and Irinotecan has been shown to be beneficial compared to a regime without Irinotecan. There was an objective response in 39% vs 21%, a longer time before tumour progression 7 months vs 4 months and a longer median survival 15 months vs 13 months (2).

Adverse effects include:

• can occur during or soon after irinotecan infusion
  • include cholinergic symptoms (e.g. flushing, diarrhoea, abdominal cramps, hypotension), which can be prevented by prophylactic subcutaneous atropine, and nausea and vomiting (generally prevented by anti-emetics)
• possible potentially serious late effects include delayed diarrhoea (typically about 5 days after infusion) and neutropenia (after 5-10 days)

The summary of product characteristics should be consulted before prescribing this drug.

Reference:

1. Drugs and Therapeutics Bulletin (2002), 40(7), 50-52.
2. Editorial NEJM (2000), 343, 963-964