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Anti-HIV nucleoside monophosphates have limited cellular uptake due to the presence of negatively-charged phosphate group. Bis-(cycloSaligenyl) derivatives containing two anti-HIV nucleosides, 3'-fluoro-3'-deoxythymidine (FLT) and 3'-azido-3'-deoxythymidine (AZT) were synthesized to increase intracellular delivery of nucleoside monophosphates. 2,5-Bis(hydroxymethylene)benzene-1,4-diol was selected as a monocyclic bidentate scaffold and synthesized by three different methods from bis(hydroxymethylene)cyclohexan-1,4-diene-1,4-diol, or diethyl 2,5-dihydroxyterephthalate. The reaction of the tetraol with diisopropylphosphoramidous dichloride in the presence of 2,6-lutidine, followed by conjugation reactions with nucleosides (i.e., FLT and AZT) and oxidation afforded symmetrical and unsymmetrical bis-(cycloSaligenyl) diphosphate triester products, AZT-AZT, FLT-FLT, and FLT-AZT conjugates, in 63-74% overall yields and modest anti-HIV activities (IC50 = 2.8-69.6 µM).

3′-Fluoro-3′-deoxy-thymidine (FDT), a fluorinated analog of 3′-azido-thymidine (AZT), is both more active against the HIV virus but also more toxic than AZT. Because of its fluorine atom, it can be labeled with 18 F to be used to monitor this drug's biodistribution and targeting. A new synthesis for FDT, suited for 18 F labeling, has been developed. After protecting the 5′-hydroxy group with a trityl group, the 3′-hydroxy group was subtituted with a mesyl group in the lyxo configuration. Treatment with 18 F potassium fluoride and crown-18 ether yielded the 18 F-labeled fluoro derivative which on detritylation afforded 18 F FDT with 7% labeling efficiency. This is the first reported synthesis of 3′- fluoro-5′-O-trityl deoxythymidine using potassium fluoride and preparing its 18 F labeled analog. The time required to incorporate 18 F in the intermediate compound and isolate the end-product is reasonably short (approximately 2 h) which will allow sufficient time to conduct biological studies with this short-lived radionuclide.

A simple and fast high-performance liquid chromatographic assay for the determination of 3′-azido-3′-deoxythymidine (AZT), 2′,3′-dideoxycytidine (ddC), 3′-fluoro-3′-deoxythymidine (FT) and 2′,3′-dideoxyinosine (ddI) in complex biological matrices is described. The method allows rapid nucleoside determination using a phenyl column within extra- as well as intracellular media without further sample pretreatment and extraction procedures. The lower limit of detection is ca. 0.05 μg/ml for each nucleoside, and the separation can easily be optimized for AZT, ddC, FT and ddI by variation of the methanolic part of the mobile phase and the detector wavelengths.

Concentrations of 3'-fluoro-3'-deoxythymidine (FDT) and 3'-deoxy-2',3'-didehydrothymidine (D4T) in plasma declined in a biexponential fashion. Total clearance of D4T (1.75 +/- 0.22 liters/h/kg; mean +/- standard deviation) was significantly greater than that of FDT (1.19 +/- 0.19 liters/h/kg) owing to greater renal and nonrenal clearances of the former. Steady-state volumes of distribution of FDT (1.20 +/- 0.12 liters/kg) and D4T (1.07 +/- 0.15 liters/kg) were similar.