RESUMO
BACKGROUND: S-1 is an oral anticancer agent that combines tegafur (FT) with 5-chloro-2,4-dihydroxypyridine (CDHP) and potassium oxonate. The recommended initial dose of S-1 is 120 mg/day for patients with a body surface area (BSA) of > or =1.5 m(2) in Japan. METHODS: We examined the effects of using this fixed dose on the pharmacokinetics of FT, CDHP, and active 5-fluorouracil (5-FU) on the basis of actual BSA. The pharmacokinetics was compared between patients with a BSA of 1.5-1.75 m(2) and those with a BSA of > or =1.75 m(2). RESULTS: The median areas under the time-concentration curves (AUCs) of 5-FU and CDHP were significantly lower in patients with a BSA of > or =1.75 m(2) than in those with a BSA of 1.5-1.75 m(2) (P = 0.005 and 0.006, respectively; Mann-Whitney U-test). There was no difference between the groups in the median AUC of FT. CONCLUSION: Systemic exposure to 5-FU is significantly lower in Japanese cancer patients with a large BSA of >1.75 m(2) who received the recommended fixed dose of S-1.
Assuntos
Antimetabólitos Antineoplásicos/administração & dosagem , Antimetabólitos Antineoplásicos/farmacocinética , Superfície Corporal , Neoplasias/tratamento farmacológico , Ácido Oxônico/administração & dosagem , Ácido Oxônico/farmacocinética , Tegafur/administração & dosagem , Tegafur/farmacocinética , Administração Oral , Idoso , Idoso de 80 Anos ou mais , Área Sob a Curva , Combinação de Medicamentos , Cálculos da Dosagem de Medicamento , Feminino , Humanos , Japão , Masculino , Pessoa de Meia-Idade , Neoplasias/etnologia , Resultado do TratamentoRESUMO
S-1 is an oral anticancer agent that combines tegafur, a prodrug of 5-fluorouracil (5-FU), and 5-chloro-2,4-dihydroxypyridine (CDHP), an inhibitor of dihydropyrimidine dehydrogenase. We examined the effects of aging on the pharmacokinetics of the components of S-1. The median area under the concentration-time curve (AUC) of active 5-FU did not significantly differ between 10 patients 75 years or older and 53 patients younger than 75 years (P = 0.598, Mann-Whitney U test). It is interesting to note that the median oral clearance of tegafur in patients 75 years or older was significantly lower than that in patients younger than 75 years (P = 0.011). Furthermore, the median AUC of CDHP was significantly higher in patients 75 years or older than in those younger than 75 years (P = 0.004). This effect was caused by reduced renal function in the elderly, because CDHP is excreted in the urine by glomerular filtration. The opposing effects of aging on the oral clearance of tegafur and the AUC of CDHP may offset each other, leading to unchanged systemic exposure of 5-FU.