famciclovir (Rx)

Brand and Other Names:Famvir
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Dosing & Uses

AdultPediatric

Dosage Forms & Strengths

tablet

  • 125mg
  • 250mg
  • 500mg
more...

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
more...

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

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    No Interactions Found
    Interactions Found

    Contraindicated

      Serious - Use Alternative

        Significant - Monitor Closely

          Minor

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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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            Formulary

            FormularyPatient Discounts

            Adding plans allows you to compare formulary status to other drugs in the same class.

            To view formulary information first create a list of plans. Your list will be saved and can be edited at any time.

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            • View the formulary and any restrictions for each plan.
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            • Compare formulary status to other drugs in the same class.
            • Access your plan list on any device – mobile or desktop.

            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.
            ST Step Therapy
            Drugs that have step therapy associated with each prescription. This restriction typically requires that certain criteria be met prior to approval for the prescription.
            OR Other Restrictions
            Drugs that have restrictions other than prior authorization, quantity limits, and step therapy associated with each prescription.
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            Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.