Famciclovir
From IDWiki
Background
- Antiviral closely related to acyclovir
- Oral prodrug to penciclovir, which is phosphorylated by viral thymidine kinase then by cellular kinases to its active triphosphate form inside of infected cells
- Competitively inhibits DNA polymerase by competing with deoxyguanosing triphosphate, getting incorporate into the replicating DNA strand and halting further replication
- Indicated for the treatment of herpes zoster virus and herpes simplex virus
- Formulations include 125 mg, 250 g, and 500 mg tablets
Dosage
- VZV: 500 mg p.o. three times daily for 7 days, started within 3 days of rash onset
- HSV:
- Recurrent genital herpes: 125 mg p.o twice daily for 5 days
- Suppression of recurrent genital herpes: 250 mg p.o. twice daily for up to 1 year
- Recurrent mucocutaneous herpes in patients with HIV: 500 mg p.o. twice daily for 7 days
Renal Dosing
| CrCl | VZV | Recurrent HSV | Suppression of HSV | Recurrent HSV in HIV |
|---|---|---|---|---|
| >60 | 500 mg q8h | 125 mg q12h | 250 mg q12h | 500 q12h |
| 40-59 | 500 q12h | |||
| 20-39 | 500 q24h | 125 mg q12h | 500 mg q24h | |
| <20 | 250 mg q24h | 125 mg q24h | 125 mg q24h | 250 mg q24h |
| HD | 250 mg after each dialysis | 125 mg after each dialysis | 125 mg after each dialysis | 250 mg after each dialysis |
