Abstract
Purpose: :
The aim of this study is to delineate the vitreal pharmacokinetics of di-peptide monoester prodrugs of ganciclovir (GCV) with conscious rabbit model using ocular microdialysis and to compare with published results from anesthetized model.
Methods: :
New Zealand albino male rabbit was selected as the animal model. Conscious animal ocular microdialysis technique with permanently implanted probes was employed to delineate the pharmacokinetics of GCV, L-valine-GCV and dipeptide monoester GCV prodrugs (L-valine-L-valine and L-glycine-L-valine) following intravitreal administration.
Results: :
The present work employs conscious model to evaluate vitreal pharmacokinetic parameters and compares the results with previously published data from anesthetized animal, thereby demonstrating the effect of anesthesia on the vitreal disposition of di-peptide prodrugs of GCV. Results have revealed that AUC, Clearance and Clast for all four compounds were significantly altered in a conscious animal relative to the anesthetized model, while MRT was significantly reduced. However, the AUCs of regenerated Val-GCV and GCV from Gly-Val-GCV and Val-Val-GCV were found to be unchanged suggesting higher ocular metabolism in conscious animals.
Conclusions: :
This study for the first time delineates the vitreal pharmacokinetics of a GCV prodrug in conscious animals and compares the data with anesthetized animals. Lower vitreal exposure levels were obtained in case of conscious animal model; however the elimination rates were not influenced by anesthesia.FIGURE 1: Vitreous concentration-time profiles of Val-GCV and regenerated ganciclovir (GCV). Mean values are represented (n=4).Vitreous concentration-time profile of ganciclovir (GCV). Mean values are represented (n=4)FIGURE 2: Vitreous concentration-time profiles of Val-Val-GCV and regenerated ganciclovir (GCV) and Val-GCV. Mean values are represented (n=4).
Keywords: antiviral drugs • vitreous • AIDS/HIV