Potentiation by acyclothymidine esters of the antitumor effect of orally administered 5-fluoro-2'-deoxyuridine esters on L1210 in mice.

The antitumor effect of 5-fluoro-2'-deoxyuridine (FUdR) esters on L1210 in mice was enhanced by the simultaneous po administration of FUdR esters and acyclothymidine [5-methyl-1-(2'-hydroxyethoxymethyl)uracil]-esters. Acyclothymidine (AcTdR), which strongly inhibits the phospholytic degradation of FUdR, was released from the AcTdR esters by enzymatic hydrolysis. The FUdR esters and AcTdR esters were found to be compatible in terms of their physicochemical properties and susceptibility to enzymatic hydrolysis.