QUANTITATION OF 3'-AMINO-3'-DEOXYTHYMIDINE (AMT), A TOXIC CATABOLITE OF 3'-AZIDO-3'-DEOXYTHYMIDINE (AZT), BY COMPETITIVE ELISA

In the present study, a competitive ELISA technique was developed to s pecifically quantitate 3'-amino-3'-deoxythymidine (AMT), a toxic catab olite of 3'-azido-3'-deoxythymidine (AZT) detected in serum from AZT-t reated patients. In order to eliminate cross-reacting AZT, serum sampl e was extracted with ethylacetate and then AMT was acetylated (Ac-AMT) . A 5'-hemisuccinate-AMT-horseradish peroxidase conjugate was used as a tracer in the presence of anti-AMT rabbit antibodies which were rais ed against a 5' hemisuccinate-AMT-bovine serum albumin immunogen. Boun d/free separation was achieved with an anti-rabbit IgG mouse monoclona l antibody insolubilized onto a microtiter plate. The limit of quantif ication of Ac-AMT was as low as 0.4 ng/ml in serum samples. This ELISA technique was applied for monitoring AMT plasma levels in patients re ceiving AZT therapy. The intra and inter-individual variations of the AZT/AMT plasma concentration ratios underlined the need for such a spe cific test in studying the formation of this toxic catabolite.