A rapid and simple HPTLC assay for therapeutic drug monitoring of capecitabine in colorectal cancer patients.

Capecitabine is a prodrug of 5-flurouracil, employed as a broad spectrum chemotherapeutic agent. It is also used as monotherapy or a combination chemotherapy agent for the treatment of colorectal cancer. Capecitabine is administered in combination with oxaliplatin and hence it is essential to determine that co-administration does not affect its metabolism. To determine the plasma concentration of capecitabine a simple HPTLC method was developed and validated. Blood samples from 12 patients with colorectal cancer were collected and analyzed by the HPTLC method with a reference internal standard. Out of these 12 patients, six were treated with capecitabine monotherapy and another six were treated with capecitabine + oxaliplatin combination therapy. The results of analysis indicated that there was no significant drug-drug interaction and the co-administration of oxaliplatin did not affect the metabolism of capecitabine. This method is sensitive, robust and specific and allows analysis of multiple samples simultaneously, making it suitable for therapeutic drug monitoring of capecitabine.