Pharmacokinetic properties of orally administered 4′-Cyano-2′-deoxyguanosine, a novel nucleoside analog inhibitor of the hepatitis B virus, in viral liver injury model rats

A nucleoside analog, 4′-cyano-2′-deoxyguanosine (CdG), which was developed as an inhibitor of the chronic hepatitis B virus (HBV), exhibited a superior antiviral activity against both wild-type and drugs-resistant HBV to marketed nucleoside analogs. In addition to previous pharmacokinetic studies of CdG in healthy rats, this study reports on an evaluation of the pharmacokinetic characteristics of CdG in a rat model of viral liver injury (VLI) induced by treatment with concanavalin A. Following an intravenous administration of CdG at a dose of 1mg/kg, the plasma concentration profile of CdG in VLI model rats was found to be similar to that of healthy rats with no significant difference in kinetic parameters. However, when CdG was orally administered at a dose of 1mg/kg, the maximum blood concentration was much lower in VLI model rats than in healthy rats. Interestingly, the amount of residual food in the stomachs in VLI model rats was significantly larger than that in healthy rats, indicating that the adsorption of CdG in the gastrointestinal tract was inhibited in the presence of food as well as other marketed nucleoside analogs. As observed in healthy rats, CdG was largely distributed to the liver compared to the kidney in the VLI model. These results suggest that liver pathology has only a minor effect on the pharmacokinetic properties of CdG, but the influence of food on CdG absorption needs to be considered.