Article ID: 09-0350
We investigated the pharmacokinetics of penciclovir after oral administration of its prodrug famciclovir to horses. Following an oral dose of famciclovir at 20 mg/kg, maximum plasma concentrations of penciclovir occurred between 0.75 and 1.5 hr (mean 0.94 ± 0.38 hr) after dosing and were in the range 2.22 to 3.56 μg/ml (mean 2.87 ± 0.61 μg/ml). The concentrations of penciclovir declined in a biphasic manner after the peak concentration was attained. The mean half-life of the rapid elimination phase was 1.73 ± 0.34 hr whereas that of the slow elimination phase was 34.34 ± 13.93 hr. These pharmacokinetic profiles observed were similar to those of another antiherpesvirus drug, acyclovir, previously reported in horses following oral dosing of its prodrug valacyclovir.