Penciclovir
from famciclovir
Pronunciation: pen-SYE-kloe-veer
What it isThe active form of famciclovir, inhibiting viral DNA polymerase; herpes simplex and zoster.
Why it mattersA long intracellular half-life allows less frequent dosing than aciclovir.
What it changesIt requires viral thymidine kinase, so TK-mutant resistant virus escapes it entirely. Renally cleared.
FDA label
Read the full label on DailyMed ↗
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Recurrent herpes labialis (cold sores) | Adults & children ≥12 yr | Apply q2h while awake × 4 days | q2h while awake × 4 days |
Renal Undefined
Hepatic Undefined
Instructions
- Topical to lips/face only — not on mucous membranes; avoid in or near eyes
- Start as early as possible (prodrome or when lesions appear)
Available strengths
- cream 1 %
Cautions
- Topical use only on herpes labialis of lips/face (no mucous membranes; avoid eyes); evaluate non-improving lesions for bacterial superinfection; not established in immunocompromised patients
Adverse reactions
- Application site reaction (1%)
- Hypesthesia/local anesthesia (<1%)
- Taste perversion (<1%)
- Erythematous rash (<1%)
Pregnancy Not absorbed systemically after topical use; maternal use not expected to cause fetal exposure.
Lactation Not absorbed systemically; breastfeeding not expected to expose the child.
Cost
Penciclovir (FROM FAMCICLOVIR)
| Strength | #/mo | generic $/unit | CostPlus | |
|---|---|---|---|---|
| 1 % | cream | per unit | not offered |
NADAC is a voluntary CMS survey of what retail community pharmacies pay for the drugs they stock. Penciclovir is dispensed outside retail pharmacies, so it rarely appears on surveyed invoices.
NO BOXED WARNINGS
Principal riskTK-mutant virus escapes it entirely