Capecitabine improves medical resource use compared with 5-fluorouracil plus leucovorin in a phase III trial conducted in patients with advanced colorectal carcinoma. Fluorouracil (FU) is an antimetabolite with activity against numerous types of neoplasms, including those of the breast, esophagus, larynx, and gastrointestinal and genitourinary tracts. Systemic toxicity, including neutropenia, stomatitis, and diarrhea, often occur due to cytotoxic nonselectivity. Capecitabine was developed as a prodrug of FU, with the goal of improving tolerability and intratumor drug concentrations through tumor-specific conversion to the active drug. The activation of capecitabine follows a pathway with three enzymatic steps and two intermediary metabolites, 5'-deoxy-5-fluorocytidine (5'-DFCR) and 5'-deoxy-5-fluorouridine (5'-DFUR), to form 5-fluorouracil.
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