Action of Irinotecan
Adults who have certain types of colon or rectal cancer may undergo chemotherapy treatment with irinotecan (Camptosar®). This prescription medication can be used alone or with other chemotherapy drugs, and is used when the cancer has spread to other areas of the body.
Irinotecan works by blocking the action of a certain enzyme in the body called topoisomerase I. This enzyme helps relax DNA that has been overwound, which can occur when DNA is duplicated so cells can divide. This enzyme breaks the DNA strand to relieve the strain, and then puts the strand back together. However, irinotecan binds to this enzyme and prevents it from repairing the broken DNA strand -- as a result, the DNA cannot duplicate and the cell dies.
(For more information, click Irinotecan. This resource takes a closer look at how this chemotherapy drug works to treat colon and rectal cancer, with details on dosing instructions, possible side effects, and more.)