What are the enzymes responsible for the high conversion rate of Capecitabine to 5FU?

Capecitabine is an oral prodrug that is metabolized to the active chemotherapeutic agent 5-Fluorouracil (5FU). The enzymes involved in this conversion play crucial roles in the metabolic pathway. Specifically, cytidine deaminase and thymidine phosphorylase are key players in this process.

Cytidine deaminase initiates the conversion of capecitabine to 5'-deoxy-5-fluorocytidine, which is then rapidly converted to 5FU by thymidine phosphorylase. This two-step enzymatic process is vital for effectively converting capecitabine into its active form, allowing for the targeting of cancer cells.

Understanding the roles of these enzymes is essential as it highlights the importance of metabolism in drug action, and can help in assessing individual patient responses to capecitabine therapy, especially in terms of efficacy and potential toxicity.