Determination of the Anti-HIV Drug 2′-β-Fluoro-2′, 3′-Dideoxyadenosine in Biological Fluids by Reversed-Phase HPLC

Abstract 2′-β-Fluoro-2′, 3′-dideoxyadenosine (F-ddA) is a synthetic dideoxynucleoside analogue that has been designed to overcome the acid stability problems of the anti-AIDS drug didanosine. F-ddA is also a clinical candidate and will be tested in AIDS patients upon completion of its preclinical evaluation. We have developed a straightforward reversed-phase HPLC method to measure both F-ddA and its deaminated metabolite, 2′-β-fluoro-2′, 3′-dideoxyinosine, in plasma and urine. This method employs an adenosine deaminase inhibitor to prevent sample degradation, an internal standard for quantitation, and C18 solid-phase extraction to isolate and concentrate the fluorinated dideoxynucleosides. Gradient HPLC analysis on a reversed-phase phenyl column with UV detection at 260 nm gives a limit of quantitation of 50 ng/ml (0.2 μM) for both analytes. This assay has been applied to preclinical studies in rats and monkeys to determine drug stability, disposition, metabolism and plasma kinetics.