Determination of 2'-beta-fluoro-2',3'-dideoxyadenosine, an experimental anti-AIDS drug, in human plasma by high-performance liquid chromatography.

2'-Beta-fluoro-2',3'-dideoxyadenosine (F-ddA, lodenosine) is an experimental anti-AIDS drug currently being evaluated in a Phase I clinical trial. A simple and specific HPLC method with UV detection, suitable for use in clinical studies, has been developed to determine both F-ddA and its deaminated catabolite, 2'-beta-fluoro-2',3'-dideoxyinosine (F-ddI) in human plasma. After inactivation of plasma HIV by 0.5% Triton X-100, the compounds of interest are isolated and concentrated using solid-phase extraction. Processed samples are separated by use of a pH 4.8 buffered methanol gradient on a reversed-phase phenyl column. The method has a linear range of 0.05-5 microg/ml (0.2-20 microM) and intra-assay precision is better than 8%. Analyte recovery is quantitative and plasma protein binding is minimal. In addition, drug and metabolite levels measured in Triton-treated human plasma remain stable for at least 5 months when samples are stored frozen without further treatment. Compound concentrations determined after samples are processed and then frozen for up to 1 month before analysis are also unchanged.