Famvir

Famvir

Generic: famciclovir

Famvir
DOSAGE Herpes Zoster: Famciclovir 500mg PO TID for 7-10 days
Herpes Simplex: Famciclovir 250mg PO TID x 7-10 days
GENERIC famciclovir
SIZE 125mg, 250mg, 500mg
TREATMENT REGIMEN HERPES ZOSTER HERPES SIMPLEX
Conjunctivitis: (1) Oral Antiviral (Choose one): Acyclovir 800 mg PO 5x/day x 7-10 days, Valacyclovir 1000mg PO TID x 7-10 days or Famciclovir 500mg PO TID x 7-10 days (2) Cool compresses BID (3) Erythromycin ung BID Conjunctivitis: (1) Topical Antiviral (Choose one): Viroptic 1% 5/day x 7 days or Zirgan 0.15% (gel) 5/day x 7 days
SPK Cornea: (1) Oral Antiviral (Choose one): Acyclovir 800 mg PO 5x/day x 7-10 days, Valacyclovir 1000mg PO TID x 7-10 days or Famciclovir 500mg PO TID x 7-10 days (2) Preservative-free artificial tears q1-2hrs + ung qHS Cornea Dendrites Epithelial (1) Topical Antiviral (Choose one): Viroptic 1% 9x/day x 7 days or Zirgan 0.15% (gel) 5x/day x 7 days (2) Oral Antiviral (choose one): Acyclovir 400 mg PO 5x/day x 7-10 days, Valacyclovir 500mg PO TID x 7-10 days or Famciclovir 250mg PO TID x 7-10 days (3) Consider Cyclopentolate 1% TID if AC reaction or photophobia (4) DO NOT use topical steroids with epithelial
Cornea Pseudodendrites: (1) Oral Antiviral (Choose one): Acyclovir 800 mg PO 5/day x 7-10 days, Valacyclovir 1000mg PO TID x 7-10 days or Famciclovir 500mg PO TID x 7-10 days (2) Preservative-free artificial tears q1-2hrs + ung qHS (3) Topical antiviral: Zirgan 0.15% (gel) TID-QID x 7-10 days Cornea Stromal (Disciform Keratitis) (1) Cyclopentolate 1% TID (2) Antiviral prophylaxis Oral (choose one): Acyclovir 400 mg PO BID or Valacyclovir 500mg PO qDay to BID (3) Antiviral prophylaxis Drops (choose one): Viroptic 1% TID or Zirgan 0.15% (gel) 3-5/day (4) If moderate/Severe with central vision loss: Add on Predforte 1% q2hr to QID
Stromal Cornea Keratitis: (1) Oral Antiviral (Choose one): Acyclovir 800 mg PO 5/day x 7-10 days, Valacyclovir 1000mg PO TID x 7-10 days or Famciclovir 500mg PO TID x 7-10 days (2) Predforte 1% 4-8/day, then taper, usually with weaker steroid with goal of q1week.
INDICATIONS Indicated for acute herpes zoster and herpes simplex infections Use oral treatment when topical toxicity is encountered. Initiate treatment within 6 hrs of symptom onset if possible
MECHANISM OF ACTION guanine analogue antiviral: Famciclovir is a prodrug of penciclovir which is absorbed poorly when given orally. Activated form inhibits viral DNA polymerase, impairing virus replication within the cell.
MICROBIOLOGY Famciclovir is a prodrug of penciclovir, which has demonstrated inhibitory activity against herpes simplex virus types 1 (HSV-1) and 2 (HSV-2). In cells infected with HSV-1 or HSV-2 the viral thymidine kinase phosphorylates penciclovir to a monophosphate form that, in turn, is converted by cellular kinases to the active form penciclovir triphosphate. Biochemical studies demonstrate that penciclovir triphosphate inhibits HSV-2 DNA polymerase competitively with deoxyguanosine triphosphate. Consequently, herpes viral DNA synthesis and, therefore, replication are selectively inhibited. Penciclovir triphosphate has an intracellular half-life of 10 hours in HSV-1- and 20 hours in HSV-2-infected cells grown in culture. However, the clinical significance of the intracellular half-life is unknown.
CONTRAINDICATIONS & WARNINGS Famciclovir tablets are contraindicated in patients with known hypersensitivity to the product, its components, or penciclovir cream. Acute renal failure: Cases of acute renal failure have been reported in patients with underlying renal disease who have received inappropriately high doses of famciclovir for their level of renal function.
PEDIATRIC USE The efficacy of famciclovir tablets have not been established in pediatric patients.
PREGNANCY Category B. After oral administration, famciclovir (prodrug) is converted to penciclovir (active drug). There are no adequate and well-controlled studies of famciclovir or penciclovir use in pregnant women. No adverse effects on embryofetal development were observed in animal reproduction studies using famciclovir and penciclovir at doses higher than the maximum recommended human dose (MRHD) and human exposure. Because animal reproduction studies are not always predictive of human response, famciclovir should be used during pregnancy only if needed.
NOTE Steroids are indicated with stromal involvement, maintaining antiviral coverage if the epithelium is compromised.
Two thirds of early Acanthamoeba keratitis are misdiagnosed as HSV