Capecitabine - Usp/ip

Capecitabine is a new oral fluoropyrimidine carbamate for patients with advanced neoplastic disease, approved as Xeloda for the treatment of refractory metastatic breast cancer after failure on Paclitaxel and an anthracycline-based chemotherapy regimen ; it is a prodrug of doxifluridine (5-fluorouracil ; 5-FU) activated by a cascade of 3 enzymes concentrated in human liver and cancer tissue, resulting in the selective release of 5-FU at the tumor site and offering a prolonged tumour exposure to 5-FU. Oral Capecitabine passes intact through the intestinal mucosa, is converted first by carboxylesterase to 5'-deoxy-5- fluorocytidine in the liver, then by cytidine deaminase to 5'-deoxy-5-fluorouridine in the liver and tumour tissues and finally by thymidine phosphorylase to 5-FU in tumors. Therefore, Xeloda is much safer and more effective than 5-FU (for example, in the HCT116 human colon cancer and the MX-1 breast cancer xenograft .models).