Capecitabine

Capecitabine is a novel oral fluoropyrimidine carbamate. Capecitabine is a prodrug, that is enzymatically converted to 5-fluorouracil in the tumor, where it inhibits DNA synthesis and slows growth of tumor tissue. Capecitabine may inhibit cytochrome CYP2C9 enzyme, and therefore increase levels of substrates such as phenytoin and other substrates of CYP2C9. Capecitabine has shown varying degrees of efficacy with acceptable tolerability in numerous cancers including prostate, renal cell, ovarian, and pancreatic, with the largest amount of evidence in metastatic breast and colorectal cancer. After oral administration of 1250 mg/m2, capecitabine is rapidly and extensively absorbed from the gastrointestinal tract [with a time to reach peak concentration (tmax) of 2 hours and peak plasma drug concentration (Cmax) of 3 to 4 mg/L] and has a relatively short elimination half-life (t(1/2)) [0.55 to 0.89 h]. Capecitabine has been reported to increase serum phenytoin levels and the international normalized ratio in patients receiving concomitant phenytoin and warfarin, respectively.