famciclovir (Rx)

Brand and Other Names:Famvir
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Dosing & Uses

AdultPediatric

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

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Interactions

Interaction Checker

and famciclovir

No Results

     activity indicator 
    No Interactions Found
    Interactions Found

    Contraindicated

      Serious - Use Alternative

        Significant - Monitor Closely

          Minor

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             activity indicator 

            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 - Use Alternative (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 (5)

            • 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. .

            • 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.

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            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

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            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)

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            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.

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            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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            Images

            BRAND FORM. UNIT PRICE PILL IMAGE
            famciclovir oral
            -
            500 mg tablet
            famciclovir oral
            -
            250 mg tablet
            famciclovir oral
            -
            125 mg tablet
            famciclovir oral
            -
            500 mg tablet
            famciclovir oral
            -
            250 mg tablet
            famciclovir oral
            -
            125 mg tablet
            famciclovir oral
            -
            500 mg tablet
            famciclovir oral
            -
            250 mg tablet
            famciclovir oral
            -
            250 mg tablet
            famciclovir oral
            -
            125 mg tablet
            famciclovir oral
            -
            250 mg tablet
            famciclovir oral
            -
            125 mg tablet
            famciclovir oral
            -
            500 mg tablet
            famciclovir oral
            -
            125 mg tablet
            famciclovir oral
            -
            500 mg tablet
            famciclovir oral
            -
            500 mg tablet
            famciclovir oral
            -
            250 mg tablet
            famciclovir oral
            -
            125 mg tablet

            Copyright © 2010 First DataBank, Inc.

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            Patient Handout

            Patient Education
            famciclovir oral

            FAMCICLOVIR - ORAL

            (fam-SYE-kloe-vir)

            COMMON BRAND NAME(S): Famvir

            USES: Famciclovir is used to treat infections caused by certain types of viruses. It treats shingles caused by herpes zoster. It also treats outbreaks of herpes simplex that cause cold sores around the mouth, sores around the anus, and genital herpes. In people with frequent outbreaks of genital herpes, famciclovir is used to help reduce the number of future episodes.Famciclovir is an antiviral drug. However, it is not a cure for these infections. The viruses that cause these infections continue to live in the body even between outbreaks. Famciclovir decreases the severity and length of these outbreaks. It helps the sores heal faster, keeps new sores from forming, and decreases pain/itching. This medication may also help reduce how long pain remains after the sores heal. In addition, in people with a weakened immune system, famciclovir can decrease the risk of the virus spreading to other parts of the body and causing serious infections.

            HOW TO USE: Read the Patient Information Leaflet if available from your pharmacist before you start taking famciclovir and each time you get a refill. If you have any questions, ask your doctor or pharmacist.Take this medication by mouth with or without food, usually 2 to 3 times a day or as directed by your doctor.This medication works best when started at the first sign of an outbreak, as directed by your doctor. It may not work as well if you delay treatment.The dosage is based on your medical condition and response to treatment.This medication works best when the amount of drug in your body is kept at a constant level. Take this drug at evenly spaced intervals. To help you remember, take it at the same times each day.Continue to take this medication until the full prescribed amount is finished. Do not change your dose, skip any doses, or stop this medication early without your doctor's approval.Tell your doctor if your condition persists or worsens.

            SIDE EFFECTS: Headache, nausea, and diarrhea may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.Tell your doctor right away if you have any serious side effects, including: mental/mood changes (such as agitation, slowed thinking, confusion, hallucinations), dizziness, drowsiness, signs of kidney problems (such as change in the amount of urine), yellowing eyes/skin, easy bruising/bleeding.A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.In the US -Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

            PRECAUTIONS: Before taking famciclovir, tell your doctor or pharmacist if you are allergic to it; or to penciclovir; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.Before using this medication, tell your doctor or pharmacist your medical history, especially of: kidney problems.This drug may rarely make you dizzy or drowsy. Alcohol or marijuana (cannabis) can make you more dizzy or drowsy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).This medication may contain lactose. If you have certain conditions such as galactose intolerance, severe lactase deficiency (not lactose or milk intolerance), or glucose-galactose malabsorption that require you to restrict your intake of lactose, consult your doctor or pharmacist before taking this medication.Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).Do not have certain immunizations/vaccinations (such as vaccines against the varicella virus) without the consent of your doctor.Older adults may be more sensitive to the side effects of this drug, especially dizziness, drowsiness, confusion, and change in the amount of urine (kidney problems).Famciclovir does not protect against the spread of genital herpes. To lower the chance of giving herpes to your partner, do not have sexual contact during an outbreak or if you have symptoms. You can spread genital herpes even if you do not have symptoms. Always use an effective barrier method (latex or polyurethane condoms/dental dams) during all sexual activity. Consult your doctor or pharmacist for more details.During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.It is unknown if this medication passes into breast milk. It may have undesirable effects on a nursing infant. Consult your doctor before breast-feeding.

            DRUG INTERACTIONS: Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

            OVERDOSE: If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center.

            NOTES: Do not share this medication with others.This medication has been prescribed for your current condition only. Do not use it later for another infection unless your doctor tells you to.

            MISSED DOSE: If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.

            STORAGE: Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets.Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.

            Information last revised August 2021. Copyright(c) 2021 First Databank, Inc.

            IMPORTANT: HOW TO USE THIS INFORMATION: This is a summary and does NOT have all possible information about this product. This information does not assure that this product is safe, effective, or appropriate for you. This information is not individual medical advice and does not substitute for the advice of your health care professional. Always ask your health care professional for complete information about this product and your specific health needs.

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            Formulary

            FormularyPatient Discounts

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            The above information is provided for general informational and educational purposes only. Individual plans may vary and formulary information changes. Contact the applicable plan provider for the most current information.

            Tier Description
            1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
            2 This drug is available at a middle level co-pay. Most commonly, these are "preferred" (on formulary) brand drugs.
            3 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs.
            4 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            5 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            6 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            NC NOT COVERED – Drugs that are not covered by the plan.
            Code Definition
            PA Prior Authorization
            Drugs that require prior authorization. This restriction requires that specific clinical criteria be met prior to the approval of the prescription.
            QL Quantity Limits
            Drugs that have quantity limits associated with each prescription. This restriction typically limits the quantity of the drug that will be covered.
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            Drugs that have step therapy associated with each prescription. This restriction typically requires that certain criteria be met prior to approval for the prescription.
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