In vitro activity: Carmofur is one of the masked compounds of 5-FU, which was modified for more potent antineoplastic activity and less toxicity. Carmofur is converted in vivo into 5-FU directly or via intermetabolites, such as 1-(carboxypentylcarbamoyl)-5-fluorouracil and/or 1-(carboxypropylcarbomoyl)-5-fluorouraci. Carmofur and its metabolites gradually accumulate in the brain during continuous administration and are removed very slowly. Carmofur has potent neurotoxicity which can produce severe leucoencephalopathy resembling methotrexate leucoencephalopathy both clinically and on brain CT, together with a cerebellar syndrome similar to that following 5-FU neurotoxicity.

Cell Assay: Carmofur is a derivative of fluorouracil, an antimetabolite used as an antineoplastic agent. Target: Nucleoside antimetabolite/analog Carmofur, which is used in the clinic to treat colorectal cancers, is a potent AC inhibitor and that this property is essential to its anti-proliferative effects. Carmofur inhibited AC activity with a median effective concentration (IC50) of 29 ± 5 nM (mean ± standard error of the mean, s.e.m.; n = 4), whereas 5-FU had no such effect (IC50>1 mM). systemic administration of carmofur (10 or 30 mg-kg-1, intraperitoneal, i.p.) to mice produced a dose-dependent inhibition of AC activity in various tissues, including lungs and brain cortex.