Abstract: AIM: To study the effects of individual differences (gender, age, body surface area, and body weight) on the pharmacokinetics of capecitabine in cancer patients in hoping of providing evidence for the rational use of capecitabine in clinic. METHODS: A total of 76 patients with various solid tumors were given a single dose of 0.6 g (0.15 g, 4 tablets) capecitabine in postprandial and blood samples were collected at multiple time points. The plasma concentration of capecitabine and its active metablolite, 5-fluorouracil (5-FU) were analyzed by HPLC-MS/MS and the pharmacokinetic parameters of the drugs were calculated by Phoenix WinNonlin7.0 software. RESULTS: Following oral administration, the Cmax values of capecitabine were 49% higher in males compared to those in females. There was no difference in capecitabine AUC0-∞, 5-FU Cmax, and 5-FU AUC0-∞ between males and females. There was a negative correlation between age (26-65 years old) and Cmax value of capecitabine, whereas no correlation in capecitabine AUC0-∞, 5-FU AUC0-∞, and 5-FU with various ages; For the body surface area, there was no significant difference in the AUC0-∞ and Cmax of capecitabine in patients with different body surface areas (1.28-2.01 m2), wheras the AUC0-∞ and Cmax of 5-FU had statistical significance (P<0.05). The values were up-regulated with the decrease of body surface area. Body weights (45.0-83.0 kg) had no effect on the AUC0-∞ and Cmax of capecitabine, whereas they had statistical correlation with AUC0-∞ and Cmax of 5-FU (P<0.05). CONCLUSION: The current data indicate that different factors affect the pharmacokinetics of capeitabine differently. Among the factors, gender and age mainly affect the absorption process and body surface area and weight mainly influence the metabolism of capeitabine.

Key words: capecitabine, pharmacokinetic,  age, gender, body surface area, body weight