In vivo biodistribution, pharmacokinetic parameters, and brain uptake of 5-halo-y-methoxy(or ethoxy)-5,6-dihydro-3'-azido-3'-deoxythymidine diastereomers as potential prodrugs of 3'-azido-3'-deoxythymidine.

Important note: Information in this article was accurate in 1996. The state of the art may have changed since the publication date.

J Med Chem. 1996 Feb 16;39(4):826-33. Unique Identifier : AIDSLINE MED/96196372
Wang L; Morin KW; Kumar R; Cheraghali M; Todd KG; Baker GB; Knaus EE; Wiebe LI; University of Alberta, Edmonton, Canada.

Abstract: A new class of 5-halo-6-alkoxy-5,6-dihydro-3'-azido-3'-deoxythymidine diastereomers (5-x-6-OR -5,6-dihydro-AZTs; X = I, Br, Cl; R = Me, Et) were evaluated as potential anti-AIDS prodrugs of 3'-azido-3'-deoxythimidine (AZT). In vivo regeneration of AZT from these 5-X-6-OR-5,6-dihydro-AZTs was examined in Balb/c mice after intravenous tail vein injection. The (5R,6R)- and (5S,6S)-5-bromo(or iodo)-6-methoxy-5,6-dihydro derivatives of AZT (BMAZT, IMAZT) were rapidly converted to AZT, resulting in AZT plasma concentrations after a 144 micromol/kg dose similar to those after an equivalent dose (144 microg/kg, 38.5 mg/kg) of AZT, whereas AZT was not detectable by HPLC after the same dose of the chloro diastereomer (5R,6R)-CMAZT. The interaction of AZT and the 5-X-6-methoxy-5,6dihydro-AZT diastereomers with the 6-[(4-nitrobenzyl)thio]-9-beta-D-ribofuranosylpurine equilibrative-sensitive nucleoside transporter in murine erythrocytes was also studied. The (5R,6R)- and (5S,6S)-5-X-6-OMe-5,6-dihydro-AZT diastereomers demonstrated a high affinity (K(i) = 0.2-0.5 mM) for the transporter relative to AZT (K(i) = 1.3 mM), with the exception of (5S,6R)-5-chloro-6-methoxy-5,6-dihydro-3'-azido-3'-deoxythymidine (CMAZT) which has a K(i) value larger than 1.5 mM. [2-(14)C]-Labeled (5R,6R)- and (5S,6S)-5-bromo-6-methoxy(or ethoxy)- 5,6-dihydro-3'-azido-3'-deoxythymidines were synthesized by the regiospecific addition of methyl hypobromite or ethyl hypobromite to the 5,6-olefinic bond of [2-(14)C]-AZT in high radiochemical yield [(5R,6R)-BMAZT, 48%, and (5S,6S)-BMAZT, 33%; (5R,6R)-BEAZT, 61%, and (5S,6S)-BEAZT, 15%), high radiochemical purity (>98%), and high specific activity (56mCi/mmol)]. The amounts of radioactivity in mouse brain after iv injection of [2-(14))C]-labeled (5R,6R)-BMAZT, (5S,6S)-BMAZT, or (5R,6R)-BEAZT were 2-4 fold higher that that for [2-(14)C]-AZT (P < 0.05). The radioactivity remaining in blood after dosing with these 5-bromo-6-alkoxy-5,6-dihydro-AZTs was up to 20-fold higher than after injection of [2-(14)C]-AZT at longer time intervals after injection. The amounts of radioactivity present in femoral bone following injection of [2(-14)C]-AZT, or these 5-bromo-6-alkoxy-5,6-dihydro-AZTs, were similar. Subcellular and regional distributions of [2-(14)C]-labeled AZT, (5R,6R)-BMAZT, or (5R,6R)-BEAZT in mouse brain after jugular vein injection did not show preferential concentration in any particular subcellular fraction nor a marked preferential regional localization for either AZT or these 5,6-dihydro prodrugs of AZT.

Keywords: Acquired Immunodeficiency Syndrome/DRUG THERAPY Animal Antiviral Agents/CHEMICAL SYNTHESIS/PHARMACOLOGY/ *PHARMACOKINETICS Bone and Bones/METABOLISM Brain/*METABOLISM Carbon Radioisotopes Comparative Study Dideoxynucleosides/CHEMICAL SYNTHESIS/PHARMACOLOGY/ *PHARMACOKINETICS Erythrocytes/DRUG EFFECTS/METABOLISM Human Indicators and Reagents Mice Mice, Inbred BALB C Prodrugs/CHEMICAL SYNTHESIS/PHARMACOLOGY/*PHARMACOKINETICS Radioisotope Dilution Technique Stereoisomers Structure-Activity Relationship Support, Non-U.S. Gov't Tissue Distribution Zidovudine/*ANALOGS & DERIVATIVES/*PHARMACOKINETICS JOURNAL ARTICLE
960930
M9690903

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