In vivo distribution and the activation of HCFU were studied by using rabbitsand mice bearing Sarcoma 180 following oral administration, and the phamacokineticbehaviours were compared with other masked type derivatives of 5-FU.
HCFU was absorbed gradually from gastrointestinal tracts, and HCFU and theoxidation products (CPEFU, CPRFU, etc.), (HCFU fraction) persisted for severalhours in the tissues and they were successively converted to 5-FU.
HCFU fraction and 5-FU distributed highly in the stomach, kidney and urinebladderand slightly in the brain and spleen. A relative high concentration of 5-FUwas detected in the tumor tissues and lung, lip, rectum, skin, etc.
5-FU level in the tumors was elevated by co-administration of HCFU withthymine, thymidine or uracil. Among them, thymine had the strongest effects toincrease 5-FU level and anticancer activities to Sarcoma 180.
The production of 5-FU from HCFU was not influenced by pre-treatments ofphenobarbital and glutathione, or CCl
4. This indicates that the activation of HCFU is not mainly depend to the liver.
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