Antiviral activities and pharmacokinetics of penciclovir and famciclovir in Pekin ducks chronically infected with duck hepatitis B virus

Famciclovir (FCV) is the oral form of the potent and selective antiherpesvirus agent penciclovir (PCV). In order to provide more information on the spectrum of activity of PCV, the activities of FCV and PCV against duck hepatitis B virus (DHBV) in chronically infected ducks were examined. As part of this investigation, the oral pharmacokinetics of FCV and PCV were determined in ducks. Oral treatment of DHBV-infected ducks (twice daily for 21 days) with either PCV (20 mg kg(-1) or 100 mg kg(-1)) or FCV (5 mg kg(-1) or 25 mg kg(-1)) suppressed virus replication, as measured by both plasma viral DNA and DNA polymerase levels. Both markers were reduced to undetectable levels within 4 days of the start of treatment, and after the cessation of treatment there was a delay of 2 to 8 days before plasma DHBV DNA and DNA polymerase levels began to increase, indicating that virus replication had resumed. The demonstration of efficacy of PCV and its oral form FCV against DHBV suggested that the two compounds may have clinical benefits. against human hepatitis B virus. Clinical trials are currently ongoing.