TOMUDEX, marketed by Hospira, is a chemotherapeutic agent used in the treatment of various types of cancer, including colorectal cancer. Its active ingredient is raltitrexed, which belongs to the class of antifolate chemotherapy drugs. TOMUDEX works by inhibiting thymidylate synthase, an enzyme necessary for DNA synthesis, thereby preventing cancer cells from proliferating and leading to their death. It is typically administered intravenously and is used either alone or in combination with other chemotherapy agents, depending on the specific cancer type and stage. As with many chemotherapy drugs, TOMUDEX can cause side effects, which may include nausea, vomiting, and myelosuppression, among others. Its use is generally indicated for patients for whom first-line treatments have not been effective or suitable.