Capecitabin

Capecitabin, more commonly written capecitabine, is an oral anticancer drug that acts as a prodrug of 5-fluorouracil (5-FU). After ingestion, capecitabine undergoes a three-step enzymatic activation, with final conversion to 5-FU occurring preferentially in tumor tissue where thymidine phosphorylase activity is relatively high. This design aims to deliver active 5-FU to cancer cells while limiting systemic exposure.

Clinical use and indications: Capecitabine is approved for several solid tumors, most notably metastatic colorectal cancer and metastatic breast cancer. In colorectal cancer it may be used as monotherapy or in combination with oxaliplatin (the CAPOX/XELOX regimen) and can serve as adjuvant therapy in selected regimens. In breast cancer, it is used as monotherapy after progression on other chemotherapies and, in combination with docetaxel, for metastatic disease.

Administration and dosing: Capecitabine is taken by mouth, typically twice daily in a 14-day-on, 7-day-off cycle, with the exact dose tailored to body size, renal function, and tolerability. It is generally recommended to take doses with water after a meal. Dose adjustments are common to manage toxicity, particularly in patients with kidney impairment or those experiencing adverse effects.

Adverse effects and precautions: The most characteristic side effect is hand-foot syndrome (palmar-plantar erythrodysesthesia). Other frequent adverse effects include diarrhea, nausea, mucositis, vomiting, fatigue, and cytopenias. Severe hepatotoxicity, nephrotoxicity, dehydration, and infections can occur. Capecitabine may interact with anticoagulants such as warfarin, increasing bleeding risk. It is contraindicated in pregnancy and requires careful monitoring of liver and kidney function.

History: Capecitabine was developed in the 1990s and marketed as Xeloda. As a prodrug of 5-FU, it provides systemic anti-tumor activity with tumor-targeted activation.