Abstract
The inhibitory effect of N6-butyrylcordycepin (7904), one of purine nucleoside analogues, on potentially lethal damage repair (PLDR) in vivo was tested using two experimental tumors, EMT6 sarcoma and SCCVII carcinoma, by an in vivo-in vitro assay. The drug had been reported to be the most potent PLDR inhibitor in vivo. In both tumors, PLDR was apparent in the experimental dose range of 15-35 Gy. However, 100 mg/kg and 200 mg/kg of the 7904 had no inhibitory effect on PLDR in EMT6 tumors, and 200 mg/kg had little effect in SCCVII tumors. Measurement of drug concentrations in the blood by high-performance liquid chromatography showed a low peak level and a relatively short half-life. This was considered to be a cause of the ineffectiveness in vivo.
