Famciclovir
Famciclovir is an oral antiviral medicine that is converted in the body to penciclovir. Famvir is the attached single-ingredient tablet record, with 250 mg and 500 mg strengths.
Key points
- Famciclovir is a prodrug of penciclovir, which inhibits herpesvirus DNA replication.
- Famvir 250 mg and 500 mg tablets contain famciclovir alone.
- Its established roles include herpes zoster and selected recurrent herpes simplex episodes.
- It controls viral replication but does not remove latent herpesvirus from the body.
Why treatment timing matters
Herpesviruses remain latent between episodes. Famciclovir acts during viral replication, so the timing of treatment relative to a rash, pain or prodromal symptoms can matter. The Famvir record connects to herpes zoster and other herpesvirus indications.
The duration and schedule are not interchangeable across shingles, recurrent genital herpes and cold sores. The 250 mg and 500 mg catalogue strengths therefore identify presentations, not complete regimens.
Kidney function changes exposure
Penciclovir is cleared mainly through the kidneys. Reduced renal function can increase exposure, and official labelling provides adjusted regimens according to kidney function and clinical use. That makes renal status an important part of product review.
Headache and nausea are among commonly reported effects. Confusion, dizziness or unusual drowsiness warrants attention, especially in an older person or someone with impaired renal function. Famciclovir can reduce the severity or duration of an episode, but transmission precautions remain relevant because treatment does not eradicate infection.