Dosing & Uses
Dosage Forms & Strengths
tablet
- 125mg
- 250mg
- 500mg
Acute Herpes Zoster (Shingles)
Treatment in immunocompetent adults
500 mg PO q8hr for 7 days; initiated within 72 hours of symptom or lesion onset
Herpes Labialis
Treatment of initial and recurrent episodes or suppressive therapy in immunocompetent adults
Initial episode: 250 mg PO q8hr for 7-10 days
Suppressive therapy: 250 mg PO q12hr for 12 months
Recurrent episodes: 1500 mg PO once; initiate therapy at first sign (within 1 hour) of symptoms such as tingling, itching or burning
Genital Herpes
Treatment of initial and recurrent episodes or suppressive therapy in immunocompetent adults
Initial episode (off-label): 250 mg PO q8hr for 7-10 days
Suppressive therapy: 250 mg PO q12hr for up to 12 months
Recurrent episodes: 1000 mg PO q12hr for 1 day; initiated within 6 hours of symptom or lesion onset
Herpes (HIV-Infected Adults)
Prevention of herpes simplex virus (HSV) reactivation and treatment of recurrent episodes
Prevention of HSV reactivation: 500 mg PO q12hr
Recurrent episodes: 500 mg PO q12hr for 5-10 days; initiated within 48 hours of symptom or lesion onset
Dosing Modifications
Acute herpes zoster
- CrCl ≥60 mL/min: Regular dosage
- CrCl 40-59 mL/min: 500 mg q12hr
- CrCl 20-39 mL/min: 500 mg once daily
- CrCl <20 mL/min: 250 mg once daily
- Hemodialysis: 250 mg after each session
Herpes labialis
- CrCl ≥60 mL/min: Regular dosage
- CrCl 40-59 mL/min: 750 mg once
- CrCl 20-39 mL/min: 500 mg once
- CrCl <20 mL/min: 250 mg once
- Hemodialysis: 250 mg once after dialysis
Genital herpes (treatment of recurrent disease)
- CrCl ≥60 mL/min: Regular dosage
- CrCl 40-59 mL/min: 500 mg q12hr for 1 day (2 doses total)
- CrCl 20-39 mL/min: 500 mg once
- CrCl <20 mL/min: 250 mg once
- Hemodialysis: 250 mg once after dialysis
Genital herpes (suppressive therapy)
- CrCl ≥40 mL/min: Regular dosage
- CrCl 20-39 mL/min: 125 mg q12hr
- CrCl <20 mL/min: 125 mg/day
- Hemodialysis: 125 mg after each session
Herpes (HIV-infected adults)
- CrCl ≥40 mL/min: Regular dosage
- CrCl 20-39 mL/min: 500 mg/day
- CrCl <20 mL/min: 250 mg/day
- Hemodialysis: 250 mg after each session
Dosage Forms & Strengths
tablet
- 125mg
- 250mg
- 500mg
Genital Herpes (Off-label)
Treatment of initial and recurrent episodes or suppressive therapy
<18 years: Safety and efficacy not established; may be considered in adolescents
Initial episode: 250 mg PO q8hr for 7-10 days
Suppressive therapy: 250 mg PO q12hr for up to 12 months
Recurrent episodes: 125 mg PO q12hr for 3-5 days
Renal impairment: As for adults; see Dosing Modifications
Interactions
Interaction Checker
No Results
Contraindicated
Serious
Significant - Monitor Closely
Minor
Contraindicated (2)
- varicella virus vaccine live
famciclovir will decrease the level or effect of varicella virus vaccine live by pharmacodynamic antagonism. Contraindicated. Avoid famciclovir use 24 h before and 14 days following varicella vaccine.
- zoster vaccine live
famciclovir will decrease the level or effect of zoster vaccine live by pharmacodynamic antagonism. Contraindicated. Avoid famciclovir use 24 h before and 14 days following zoster vaccine.
Serious (1)
- talimogene laherparepvec
famciclovir decreases effects of talimogene laherparepvec by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Although no drug interactions studies have been performed, antiherpetic viral agents may interfere with the effectiveness of talimogene laherparepvec.
Monitor Closely (7)
- digoxin
famciclovir increases levels of digoxin by unspecified interaction mechanism. Use Caution/Monitor. Coadministration increases digoxin Cmax by ~19%.
- probenecid
probenecid increases levels of famciclovir by acidic (anionic) drug competition for renal tubular clearance. Use Caution/Monitor. Coadministration of famciclovir with drugs that are significantly eliminated by active renal tubular secretion may increase plasma concentrations of famciclovir's active moiety (ie, penciclovir).
- raloxifene
raloxifene decreases levels of famciclovir by aldehyde dehydrogenase inhibition. Use Caution/Monitor. The conversion of 6-deoxy penciclovir to penciclovir is catalyzed by aldehyde oxidase. Interactions with other drugs metabolized by this enzyme and/or inhibiting this enzyme could potentially occur. Raloxifene, a potent aldehyde oxidase inhibitor in vitro, could decrease the formation of penciclovir.
- tenofovir DF
tenofovir DF increases levels of famciclovir by decreasing renal clearance. Use Caution/Monitor. Potential for increased toxicity. .
- ublituximab
ublituximab decreases effects of famciclovir by immunosuppressive effects; risk of infection. Use Caution/Monitor.
- xanomeline/trospium
famciclovir, xanomeline/trospium. Either increases levels of the other by decreasing elimination. Use Caution/Monitor. Coadministration of trospium with other drugs eliminated by active tubular secretion may increase plasma concentrations of trospium and/or the concomitantly used drug owing to competition for this elimination pathway. Monitor for increased frequency and/or severity of adverse reactions.
- zoster vaccine recombinant
famciclovir decreases effects of zoster vaccine recombinant by pharmacodynamic antagonism. Use Caution/Monitor. Immunosuppressive therapies may reduce the effectiveness of zoster vaccine recombinant.
Minor (2)
- cimetidine
cimetidine, famciclovir. aldehyde dehydrogenase inhibition. Minor/Significance Unknown. The conversion of 6-deoxy penciclovir to penciclovir is catalyzed by aldehyde oxidase. Interactions with other drugs metabolized by this enzyme and/or inhibiting this enzyme could potentially occur. Clinical interaction studies of famciclovir with cimetidine did not show relevant effects on the formation of penciclovir.
- promethazine
promethazine, famciclovir. aldehyde dehydrogenase inhibition. Minor/Significance Unknown. The conversion of 6-deoxy penciclovir to penciclovir is catalyzed by aldehyde oxidase. Interactions with other drugs metabolized by this enzyme and/or inhibiting this enzyme could potentially occur. Clinical interaction studies of famciclovir with promethazine did not show relevant effects on the formation of penciclovir.
Adverse Effects
>10%
Headache (23%)
Nausea (13%)
1-10%
Diarrhea (2-9%)
Abdominal pain (8%)
Dysmenorrhea (<8%)
Vomiting (1-5%)
Flatulence (5%)
Pruritus (4%)
Rash (3%)
Paresthesia (3%)
Neutropenia (3%)
Increased transaminases (2-3%)
Increased bilirubin (2%)
Fatigue (1%)
<1%
Arthralgia
Confusion
Dizziness
Erythema multiforme
Hallucinations
Jaundice
Rigors
Thrombocytopenia
Upper respiratory tract infection
Postmarketing Reports
Blood and lymphatic system disorders: Thrombocytopenia
Immune system disorders anaphylactic shock and anaphylactic reaction under
Hepatobiliary disorders: Abnormal liver function tests, cholestatic jaundice
Nervous system disorders: Dizziness, somnolence, seizures
Psychiatric disorders: Confusion (including delirium, disorientation, and confusional state occurring predominantly in the elderly), hallucinations
Skin and subcutaneous tissue disorders: Urticaria, Stevens-Johnson syndrome, toxic epidermal necrolysis, angioedema (eg, face, eyelid, periorbital, pharyngeal edema), hypersensitivity vasculitis
Cardiac disorders: Palpitations
Warnings
Contraindications
Known hypersensitivity to this drug or its active metabolite, penciclovir
Cautions
Dosage must be adjusted in renal impairment; there is a risk of acute renal failure (ARF) with inappropriately high dosage
Patients with galactose intolerance, glucose-galactose malabsorption syndrome, or severe lactase deficiency should discuss it with practitioner (famciclovir tablets contain lactose)
Pregnancy & Lactation
Pregnancy
Healthcare providers are encouraged to report pregnancies and pregnancy outcomes to Novartis Adverse Event reporting line at 1-888-NOW-NOVA (669-6682)
Available data from pharmacovigilance reports in pregnant women have not identified a drug- associated risk of major birth defects, miscarriage or adverse maternal or fetal outcomes; there are risks to fetus associated with untreated herpes simplex virus during pregnancy; after oral administration, famciclovir (prodrug) is converted to penciclovir (active drug); in animal reproduction studies with famciclovir, no evidence of adverse developmental outcomes observed at systemic exposures of penciclovir (AUC) slightly higher than those at maximum recommended human dose (MRHD)
The risk of neonatal herpes infection varies from 30% to 50% for genital herpes simplex virus (HSV) infections that occur in late pregnancy (third trimester), whereas in early pregnancy, infection carries a risk of about 1%; primary herpes outbreak during first trimester of pregnancy associated with neonatal chorioretinitis, microcephaly and, in rare cases, skin lesions; in very rare cases, transplacental transmission can occur resulting in congenital infection, including microcephaly, hepatosplenomegaly, intrauterine growth restriction and stillbirth; co-infection with HSV increases the risk of perinatal HIV transmission in women who had a clinical diagnosis of genital herpes during pregnancy
Effects on reproductive potential
- Decreased fertility, due to testicular toxicity, observed in male animals following repeated administration of famciclovir or penciclovir; no evidence of significant effects on sperm count, motility or morphology during treatment or during an 8-week follow-up
Animal data
- No adverse effects on embryo-fetal (rats and rabbits) or pre/post-natal (rats) development observed up to highest dose administered orally to pregnant rats and rabbits (up to 1000 mg/kg/day) on gestation day(s) 6 to 15, and to rats on gestation day 15 to lactation/post-partum day 25; during organogenesis, systemic exposures of penciclovir (active metabolite) were 3.4 times (rats) and 1.6 times (rabbits) the human systemic exposure of penciclovir based on AUC at the MRHD
Lactation
There are no data on presence of famciclovir (prodrug) or penciclovir (active drug) in human milk, effects on breastfed infant, or on milk production; animal data indicate that penciclovir is present in the milk of lactating rats; developmental and health benefits of breastfeeding should be considered along with mother’s clinical need for therapy and any potential adverse effects on breastfed infant from therapy or from underlying maternal condition
Pregnancy Categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk. C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done. D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk. X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist. NA: Information not available.Pharmacology
Mechanism of Action
Prodrug of penciclovir, which selectively inhibits viral DNA replication in herpes simplex virus (HSV) type 1 (HSV-1), HSV-2, and varicella zoster virus (VZV)
Absorption
Bioavailability: 77%
Peak plasma time: 1 hr (penciclovir)
Food decreases Cmax and delays Tmax but does not change AUC
Distribution
Protein bound: <20% (penciclovir)
Vd: 0.91-1.25 L/kg
Metabolism
Rapidly deacetylated and oxidized to penciclovir; not metabolized via CYP isoenzymes
Metabolites: Penciclovir triphosphate (active)
Elimination
Half-life (penciclovir): 2-4 hr; prolonged with renal impairment
Excretion: Urine (73%), feces (27%)
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Formulary
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