Development and Validation of HPLC and HPTLC Methods for Therapeutic Drug Monitoring of Capecitabine in Colorectal Cancer Patients.

Capecitabine is a prodrug of 5-fluorouracil, employed as a monotherapy or combination chemotherapy agent for treatment of colorectal cancer. Combination therapy of capecitabine consists of oxaliplatin, and hence, it becomes essential to determine that co-administration does not affect its metabolism. High-performance liquid chromatography and high-performance thin-layer chromatography methods were developed and validated to determine the plasma concentration of capecitabine. In this study, blood samples from 12 patients with colorectal cancer were collected and analyzed by both methods with a reference internal standard. Two groups consisting of six patients each were formed: the first group was treated with capecitabine monotherapy, the second group with capecitabine + oxaliplatin combination therapy. The results of analysis from both the methods indicated that there is no significant drug-drug interaction. The co-administration of oxaliplatin did not affect the metabolism of capecitabine. Both assay methods were compared for their sensitivity, robustness and specificity. It was found that both the assay methods were suitable for therapeutic drug monitoring of capecitabine.