Abstract

Cosalane is a potent inhibitor of HIV replication with a broad range of activity. In this study, the hepatic disposition of cosalane was investigated with a noncirculating isolated perfused rat liver technique. When 6 μM cosalane was infused into livers from untreated rats, the drug was highly extracted by the liver (only 2.5% of influent cosalane concentration appeared in the effluent perfusate). Pretreatment of rats with various inducers of cytochrome P-450 before perfusion neither altered the effluent cosalane concentration nor resulted in the appearance of detectable metabolites in the effluent perfusate or liver homogenates. Hepatic uptake of cosalane was negligible when the drug was infused in the presence of BSA, and infusion of albumin after cosalane resulted in a significant displacement of the drug into the effluent perfusate. Furthermore, permeabilization of perfused livers with digitonin significantly diminished effluent cosalane concentration while enhancing cosalane uptake by the liver. Based on our data, it appears that a significant proportion of cosalane does not penetrate the hepatocyte membrane and may accumulate in the lipid bilayer of the cell membrane. This finding supports the proposed mechanism explaining the antiviral effect of cosalane which stipulates that this compound appears to imbed perpendicularly in the lipid bilayer of the cell membrane and the viral envelope. Also, cosalane does not seem to be metabolized by the liver as evidenced by the lack of detectable metabolites in the effluent perfusate, liver homogenates, and liver microsomal incubations.