Famciclovir, a synthetic acyclic
guanine derivative, is a
prodrug which, after
oral administration, is rapidly metabolised to the highly bioavailable
antiviral compound
penciclovir.
Penciclovir is active in vitro against the herpesviruses herpes simplex virus (HSV)-1, HSV-2 and varicella zoster virus (VZV).
Famciclovir is an effective treatment of immunocompetent patients with acute
herpes zoster (
shingles) caused by VZV. Comparative studies have demonstrated that
famciclovir has therapeutic efficacy similar to that of oral
aciclovir (
acyclovir) in attenuating the acute signs and symptoms of
infection (including
pain during the acute phase of
infection). In a placebo-controlled study,
famciclovir significantly reduced the duration of
postherpetic neuralgia; this effect was more pronounced (almost a 3-fold reduction) in patients aged > or = 50 years. In immunocompetent patients with recurrent
genital herpes infection, suppressive treatment with oral
famciclovir effectively prolonged the time to recurrence of symptomatic episodes of
infection compared with placebo. In addition,
famciclovir significantly reduced the duration of viral shedding, accelerated healing of
genital herpes lesions and reduced the duration of symptoms.
Famciclovir is reported to be the first
antiviral agent to significantly reduce symptoms associated with multiple
genital herpes lesions.
Famciclovir is a well-tolerated
drug with a tolerability profile similar to that of placebo and
aciclovir. Thus,
famciclovir is now established as an effective treatment of immunocompetent patients with
herpes zoster or
genital herpes infection, particularly as
famciclovir is administered in a convenient dosage regimen that may improve compliance compared with
aciclovir.