Pharmacokinetic Analysis of Dextran Sulfate in Rats as Pertains to Its Clinical Usefulness for Therapy of HIV Infection

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Abstract
We administered radiolabeled dextran sulfate (3H labeled on the reducing end, MW .apprxeq.8000)([3H]DS) to rats. High performance liquid chromatography (HPLC) analysis of plasma from animals that were given [3H]DS intravenously revealed an initial plasma half-life of about 30 min. Eleven percent of [3H]DS administered was recovered in the urine in 24 h; this material represented minor breakdown with a molecular weight of 4000 as determined by size exclusion HPLC analysis. When administered orally, the apparent bioavailability of [3H]DS was 6.8%, based on the recovered radioactivity; however, the molecular weight of the radioactive material obtained from the plasma was all < 200, indicating that no detectable intact dextran sulfate was absorbed upon oral administration. Only 2% of orally administered [3H]DS was found in the 24-h urine; this material also had a molecular weight < 200. Further in vitro testing of antiviral activity revealed that DS with molecular weight less than 2300 had no anti-HIV effect and that in the presence of higher concentrations of human serum, more DS was required for antiviral effect. Although the pharmacokinetics of dextran sulfate in rats can differ from those in humans to some extent, these data suggest that oral administration of DS is unlikely to produce significant antiretroviral effect against HIV in vivo and higher plasma levels of DS may be necessary than those inferred from earlier in vitro data.