[Problems of antineoplastic effects by PLDR (potential lethal damage repair) inhibitor--pharmacokinetics].

PLDR is one known cause of tumor cell radioresistance. Drugs like ara-A have been reported to inhibit PLDR, thus increasing antineoplastic effects. In this research, ara-A concentration was measured by high-pressure liquid chromatography (HPLC) to investigate its metabolism. Ara-A deaminases in vitro in about 30 minutes, but by using a deaminase inhibitor such as 2'-deoxycoformycin, a fixed level of ara-A can be maintained. Furthermore, the new derivative, ara-AMP, does not deaminase. It is hoped that antineoplastic effects can be effectively increased by maintaining the ara-A concentration through the combined use of deaminase inhibitors and through new derivatives.