KEY POINTS
- Famciclovir (Famvir) is an antiviral medication that inhibits DNA synthesis and replication
- Famciclovir undergoes rapid biotransformation to penciclovir, which is phosphorylated to a monophosphate form by viral thymidine kinase in herpes simplex virus (HSV)-1, HSV-2 and varicella zoster virus (VZV)-infected cells. It is then converted to penciclovir triphosphate, which competes with deoxyguanosine triphosphate, leading to inhibition of herpes viral DNA synthesis and replication.
- FDA-labeled and non-labeled uses for:
- Herpes zoster (shingles)
- Varicella infection (chickenpox)
- Genital herpes simplex virus
- Orolabial or labialis herpes (cold sores)
- When used for herpes, initiate therapy as soon as possible after diagnosis and within 72 hours of rash onset
- When treatment for herpes labialis is initiated within one hour of symptom onset, healing time is reduced by about two days
- Tablets contain lactose, not recommended for patients with galactose intolerance, severe lactase deficiency, or glucose-galactose malabsorption syndromes
- Beware renal toxicity and be sure to adjust doses for renal function
- Common side effects are headache and nausea
RESOURCES