gimeracil and Diarrhea

To observe the efficacy and side effects of the combination therapy of oxaliplatin and S-1 in treating postoperative colorectal cancer patients.. 54 postoperative colorectal cancer patients received the combination therapy of oxaliplatin and S-1 regimen, repeated every 3 weeks, and evaluate the efficacy after 3 cycles.. All of the 54 patients but 2 (changed the chemotherapy regimen after the first cycle because of economic reason) finished 6 cycles of the chemotherapy treatment. There were 6 cases (11.5%) with complete response (CR), 28 cases (53.8%) with partial response (PR), and the overall response rate was 65.4%. Major adverse effects were hematological toxicities, gastrointestinal disturbance, neurosensory toxicity. There were no chemotherapy-related deaths.. Oxaliplatin combined with S-1 is an effective and better tolerated chemotherapy treatment for postoperative colorectal cancer patients, with no serious side effects for liver and kidney. Therefore, it can be used as an alternative chemotherapy regimen for postoperative colorectal cancer patients.

Topics: Adenocarcinoma; Adenocarcinoma, Mucinous; Aged; Antineoplastic Combined Chemotherapy Protocols; Colonic Neoplasms; Diarrhea; Female; Humans; Leukopenia; Male; Middle Aged; Organoplatinum Compounds; Oxaliplatin; Oxonic Acid; Postoperative Period; Pyridines; Rectal Neoplasms; Remission Induction; Tegafur; Vomiting

An important cytotoxic effect of 5-fluorouracil (5-FU) is the inactivation of thymidylate synthase (TS) (EC 2.1.1.45) activity by the formation of a ternary complex consisting of covalently bound 5-fluorodeoxyuridine 5'-monophosphate (FdUMP), TS and 5,10-methylenetetrahydrofolate (CH2FH4). The gastrointestinal (GI) toxicity of 5-FU is also caused by its phosphorylation in the GI tract. Potassium oxonate (O(XO)) competitively inhibits pyrimidine phosphoribosyltransferase (EC 2.4.2.10), which converts 5-FU to 5-fluorouridine 5'-monophosphate (FUMP) in vitro. In this study the benefits of combining Oxo and tegafur (FT), which is a masked compound of 5-FU, in reducing the GI toxicity of 5-FU and in protecting the activity of TS in the normal GI tissues were evaluated.. We administered orally a preparation of 1 M FT and 0.4 M 5-chloro-2,4-dihydroxypyridine (CDHP) with or without 1 M O(XO) (called S-1 and FT + CDHP, respectively) or vehicle only (control) to rats for ten consecutive days and compared the toxicity, the histopathological findings and the free TS activity in the GI tissues of the treated rats.. During the experimental periods, the signs of toxicity, such as a decrease in body weight, diarrhea and death, were only observed in the rats treated with FT + CDHP. The histopathological findings in the ileum and colon samples from rats treated consecutively with S-1 on day 1, day 4, day 7 and day 10 were less frequent and more mild than in the samples from rats treated with FT + CDHP. Furthermore, the free TS activities in the ileum samples of rats given S-1 and FT + CDHP were significantly decreased compared with the activity in samples from the control rats throughout the experimental periods. The free TS activities in GI tissues of rats treated with S-1 were higher than the TS activities in tissues from rats treated with FT + CDHP daily from day 4 to day 10, although activities in S-1-treated rat were decreased to almost same low levels as in FT + CDHP-treated rats on day 1.. Our results suggest that repeated simultaneous administration of Oxo and FT can effectively protect the activity of TS by decreasing FdUMP via FUMP from 5-FU in GI tissue, and may lead to a reduction in GI toxicity.

Topics: Animals; Antimetabolites, Antineoplastic; Body Weight; Colon; Diarrhea; Digestive System; Drug Combinations; Drug Interactions; Enzyme Inhibitors; Fluorodeoxyuridylate; Fluorouracil; Ileum; Male; Oxonic Acid; Pyridines; Rats; Tegafur; Thymidylate Synthase

S-1, an antineoplastic formulation of a fluorinated pyrimidine derivative containing tegafur (FT), CDHP, and potassium oxonate (Oxo) in a molar ratio of 1:0.4:1, was recently developed by Taiho Pharmaceutical Co., Ltd., with the aim of prolonging the effective plasma concentration of 5-fluorouracil (5-FU) over that produced by FT alone and reducing its dose-limiting gastrointestinal toxicity. As a part of the S-1 toxicity study, the single-dose toxicity of S-1 as well as that of its components, CDHP and Oxo, was investigated in mice, rats, and dogs. The following results were obtained. 1. In mice and rats, excretion of diarrheal stools, salivation, and alopecia were observed after S-1 administration. In severe cases, the animals subsequently showed emaciation due to weight loss or suppressed weight gain, decreased spontaneous motor activity, an anemic appearance, bradypnea, prone position, and death. In the CDHP and Oxo treatment groups of rats, the only toxic signs were soft or diarrheal stools on the dosing day. 2. In dogs, vomiting and excretion of diarrheal, mucous, or soft stools was observed after S-1 administration. In the CDHP and Oxo treatment groups, excretion of soft and diarrheal stools and vomiting were observed relatively frequently from the dosing day until day 1. 3. In the pathological examination of the animals given S-1, mice and rats showed pulmonary congestion/edema, dark red discoloration of the mesenteric lymph nodes, atrophy of lymphatic tissues such as the thymus and lymph nodes, decreases of lymphocytes in the splenic white pulp and mesenteric lymph nodes, a decrease in bone marrow cells, congestion of the glandular stomach, and aggregates of bacteria in the lung, liver, or spleen. In dogs, abnormal changes were observed mainly in the lymphatic organs such as the thymus and lymph nodes. 4. The LD50 values of S-1 in terms of the amount FT they contained were estimated to be 549 mg/kg for mice(male), 441-551 mg/kg for rats (both sexes) and about 53 mg/kg for dogs (male). The LD50 values of CDHP and Oxo were 2000 mg/kg or higher for both rats (both sexes) and dogs (male). 5. Hematopoietic and lymphatic impairments, immunosuppression associated with respiratory were considered to be the cause of death from S-1. The toxicity of S-1 reflects the toxicity of 5-FU and was not found the different toxicity by the addition of CDHP and Oxo.

Topics: Administration, Oral; Alopecia; Animals; Antimetabolites, Antineoplastic; Antineoplastic Combined Chemotherapy Protocols; Body Weight; Diarrhea; Dogs; Drug Combinations; Female; Lethal Dose 50; Lymph Nodes; Male; Mice; Motor Activity; Oxonic Acid; Pyridines; Rats; Salivation; Spleen; Survival Rate; Tegafur; Thymus Gland