Radioimmunoassay for the detection and quantitation of 5-fluorodexoyuridine.

A sensitive radioimmunoassay for 5-fluorodeoxyuridine (FdUrd) and 5-fluoro-2'-deoxyuridine 5'-monophosphate has been developed by using antibody induced in rabbits, [3H]FdUrd, and a separation technique with nitrocellulose filters. Antibody specificity was characterized by using compounds chemically related to FdUrd and comparing their effectiveness for displacing [3H]FdUrd from the antibody-combining site. Drug levels in serum samples from patients receiving FdUrd chemotherapy were easily and rapidly determined, and the serum disappearance of the drug was followed by this method. FdUrd was also detected and quantified in urine samples. According to the antiserum used, as little as 1 to 10 pmol FdUrd were measurable.