What is famciclovir 500 mg used for?

Famciclovir

Famciclovir is an antiviral drug. It slows the growth and spread of the herpes virus so that the body can fight off the infection. Famciclovir will not cure herpes, but it can lessen the symptoms of the infections.

Famciclovir is used to treat infections caused by herpes viruses, including genital herpes, cold sores, and shingles.

There is no cure for herpes and famciclovir will not prevent you from developing symptoms in the future.

Famciclovir may also be used for purposes not listed in this medication guide.

You should not take this medication if you are allergic to famciclovir or penciclovir cream (Denavir).

Take this medicine for the full prescribed length of time. Your symptoms may improve before the infection is completely cleared.

Treatment with famciclovir should be started as soon as possible after the first appearance of symptoms (such as tingling, burning, blisters).

Herpes infections are contagious and you can infect other people, even while you are being treated with famciclovir. Avoid letting infected areas come into contact with other people. Avoid touching an infected area and then touching your eyes. Wash your hands frequently to prevent passing the infection to others.

You should not take this medication if you are allergic to famciclovir or penciclovir cream (Denavir).

To make sure you can safely take famciclovir, tell your doctor if you have any of these other conditions:

  • liver disease;
  • kidney disease;
  • a weak immune system;
  • galactose intolerance;
  • severe lactase deficiency; or
  • glucose-galactose malabsorption.

FDA pregnancy category B. This medication is not expected to be harmful to an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant during treatment. Herpes virus can be passed from an infected mother to her baby during childbirth. If you have genital herpes, it is very important to prevent herpes lesions during your pregnancy so that you do not have a genital lesion when your baby is born.

If you are pregnant, your name may be listed on a pregnancy registry. This is to track the outcome of the pregnancy and to evaluate any effects of famciclovir on the baby.

It is not known whether famciclovir passes into breast milk, or if it could harm a nursing baby. Do not take famciclovir without telling your doctor if you are breast-feeding a baby.

Do not give this medication to anyone under 18 years old without medical advice.

Famvir

WARNINGS

Included as part of the “PRECAUTIONS” Section

PRECAUTIONS

Acute Renal Failure

Cases of acute renal failure have been reported in patients with underlying renal disease who have received inappropriately high doses of FAMVIR for their level of renal function. Dosage reduction is recommended when administering FAMVIR to patients with renal impairment .

Patient Counseling Information

Advise the patient to read the FDA-approved patient labeling (Patient Information).

There is no evidence that FAMVIR will affect the ability of a patient to drive or to use machines. However, patients who experience dizziness, somnolence, confusion or other central nervous system disturbances while taking FAMVIR should refrain from driving or operating machinery.

Because FAMVIR contains lactose (FAMVIR 125 mg, 250 mg, and 500 mg tablets contain lactose 26.9 mg, 53.7 mg and 107.4 mg, respectively), patients with rare hereditary problems of galactose intolerance, a severe lactase deficiency or glucose-galactose malabsorption should be advised to discuss with their healthcare provider before taking FAMVIR.

Herpes Labialis (Cold Sores)

Patients should be advised to initiate treatment at the earliest sign or symptom of a recurrence of cold sores (e.g., tingling, itching, burning, pain, or lesion). Patients should be instructed that treatment for cold sores should not exceed 1 dose. Patients should be informed that FAMVIR is not a cure for cold sores.

Genital Herpes

Patients should be informed that FAMVIR is not a cure for genital herpes. There are no data evaluating whether FAMVIR will prevent transmission of infection to others. Because genital herpes is a sexually transmitted disease, patients should avoid contact with lesions or intercourse when lesions and/or symptoms are present to avoid infecting partners. Genital herpes is frequently transmitted in the absence of symptoms through asymptomatic viral shedding. Therefore, patients should be counseled to use safer sex practices.

If episodic therapy for recurrent genital herpes is indicated, patients should be advised to initiate therapy at the first sign or symptom of an episode.

There are no data on safety or effectiveness of chronic suppressive therapy of longer than 1-year duration.

Herpes Zoster (Shingles)

There are no data on treatment initiated more than 72 hours after onset of zoster rash. Patients should be advised to initiate treatment as soon as possible after a diagnosis of herpes zoster.

Nonclinical Toxicology

Carcinogenesis, Mutagenesis, Impairment Of Fertility

Carcinogenesis

Two-year dietary carcinogenicity studies with famciclovir were conducted in rats and mice. An increase in the incidence of mammary adenocarcinoma (a common tumor in animals of this strain) was seen in female rats receiving the high dose of 600 mg/kg/day (1.1 to 4.5x the human systemic exposure at the recommended total daily oral dose ranging between 500 mg and 2000 mg, based on area under the plasma concentration curve comparisons for penciclovir). No increases in tumor incidence were reported in male rats treated at doses up to 240 mg/kg/day (0.7 to 2.7x the human AUC), or in male and female mice at doses up to 600 mg/kg/day (0.3 to 1.2x the human AUC).

Mutagenesis

Famciclovir and penciclovir (the active metabolite of famciclovir) were tested for genotoxic potential in a battery of in vitro and in vivo assays. Famciclovir and penciclovir were negative in in vitro tests for gene mutations in bacteria (S. typhimurium and E. coli) and unscheduled DNA synthesis in mammalian HeLa 83 cells (at doses up to 10,000 and 5,000 mcg/plate, respectively). Famciclovir was also negative in the L5178Y mouse lymphoma assay (5000 mcg/mL), the in vivo mouse micronucleus test (4800 mg/kg), and rat dominant lethal study (5000 mg/kg). Famciclovir induced increases in polyploidy in human lymphocytes in vitro in the absence of chromosomal damage (1200 mcg/mL). Penciclovir was positive in the L5178Y mouse lymphoma assay for gene mutation/chromosomal aberrations, with and without metabolic activation (1000 mcg/mL). In human lymphocytes, penciclovir caused chromosomal aberrations in the absence of metabolic activation (250 mcg/mL). Penciclovir caused an increased incidence of micronuclei in mouse bone marrow in vivo when administered intravenously at doses highly toxic to bone marrow (500 mg/kg), but not when administered orally.

Impairment Of Fertility

Testicular toxicity was observed in rats, mice, and dogs following repeated administration of famciclovir or penciclovir. Testicular changes included atrophy of the seminiferous tubules, reduction in sperm count, and/or increased incidence of sperm with abnormal morphology or reduced motility. The degree of toxicity to male reproduction was related to dose and duration of exposure. In male rats, decreased fertility was observed after 10 weeks of dosing at 500 mg/kg/day (1.4 to 5.7x the human AUC). The no observable effect level for sperm and testicular toxicity in rats following chronic administration (26 weeks) was 50 mg/kg/day (0.15 to 0.6x the human systemic exposure based on AUC comparisons). Testicular toxicity was observed following chronic administration to mice (104 weeks) and dogs (26 weeks) at doses of 600 mg/kg/day (0.3 to 1.2x the human AUC) and 150 mg/kg/day (1.3 to 5.1x the human AUC), respectively.

Famciclovir had no effect on general reproductive performance or fertility in female rats at doses up to 1000 mg/kg/day (2.7 to 10.8x the human AUC).

Two placebo-controlled studies in a total of 130 otherwise healthy men with a normal sperm profile over an 8-week baseline period and recurrent genital herpes receiving oral FAMVIR (250 mg twice daily) (n=66) or placebo (n=64) therapy for 18 weeks showed no evidence of significant effects on sperm count, motility or morphology during treatment or during an 8-week follow-up.

Use In Specific Populations

Pregnancy

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.

In animal reproduction studies, pregnant rats and rabbits received oral famciclovir at doses (up to 1000 mg/kg/day) that provided 2.7 to 10.8 times (rats) and 1.4 to 5.4 times (rabbits) the human systemic exposure based on AUC. No adverse effects were observed on embryo-fetal development. In other studies, pregnant rats and rabbits received intravenous famciclovir at doses (360 mg/kg/day) 1.5 to 6 times (rats) and (120 mg/kg/day) 1.1 to 4.5 times (rabbits) or penciclovir at doses (80 mg/kg/day) 0.3 to 1.3 times (rats) and (60 mg/kg/day) 0.5 to 2.1 times (rabbits) the MRHD based on body surface area comparisons. No adverse effects were observed on embryo-fetal development.

Pregnancy Exposure Reporting

To monitor maternal-fetal outcomes of pregnant women exposed to FAMVIR, Novartis Pharmaceuticals Corporation maintains a FAMVIR Pregnancy Reporting system. Physicians are encouraged to report their patients by calling 1-888-NOW-NOVA (669-6682).

Nursing Mothers

It is not known whether famciclovir (prodrug) or penciclovir (active drug) are excreted in human milk. Following oral administration of famciclovir to lactating rats, penciclovir was excreted in breast milk at concentrations higher than those seen in the plasma. There are no data on the safety of FAMVIR in infants. FAMVIR should not be used in nursing mothers unless the potential benefits are considered to outweigh the potential risks associated with treatment.

Pediatric Use

The efficacy of FAMVIR has not been established in pediatric patients. The pharmacokinetic profile and safety of famciclovir (experimental granules mixed with OraSweet® or tablets) were studied in 3 open-label studies.

Study 1 was a single-dose pharmacokinetic and safety study in infants 1 month to <1 year of age who had an active herpes simplex virus (HSV) infection or who were at risk for HSV infection. Eighteen subjects were enrolled and received a single dose of famciclovir experimental granules mixed with OraSweet based on the patient’s body weight (doses ranged from 25 mg to 175 mg). These doses were selected to provide penciclovir systemic exposures similar to the penciclovir systemic exposures observed in adults after administration of 500 mg famciclovir. The efficacy and safety of famciclovir have not been established as suppressive therapy in infants following neonatal HSV infections. In addition, the efficacy cannot be extrapolated from adults to infants because there is no similar disease in adults. Therefore, famciclovir is not recommended in infants.

Study 2 was an open-label, single-dose pharmacokinetic, multiple-dose safety study of famciclovir experimental granules mixed with OraSweet in children 1 to <12 years of age with clinically suspected HSV or varicella zoster virus (VZV) infection. Fifty-one subjects were enrolled in the pharmacokinetic part of the study and received a single body weight adjusted dose of famciclovir (doses ranged from 125 mg to 500 mg). These doses were selected to provide penciclovir systemic exposures similar to the penciclovir systemic exposures observed in adults after administration of 500 mg famciclovir. Based on the pharmacokinetic data observed with these doses in children, a new weight-based dosing algorithm was designed and used in the multiple-dose safety part of the study. Pharmacokinetic data were not obtained with the revised weight-based dosing algorithm.

A total of 100 patients were enrolled in the multiple-dose safety part of the study; 47 subjects with active or latent HSV infection and 53 subjects with chickenpox. Patients with active or latent HSV infection received famciclovir twice a day for 7 days. The daily dose of famciclovir ranged from 150 mg to 500 mg twice daily depending on the patient’s body weight. Patients with chickenpox received famciclovir three times daily for 7 days. The daily dose of famciclovir ranged from 150 mg to 500 mg three times daily depending on the patient’s body weight. The clinical adverse events and laboratory test abnormalities observed in this study were similar to these seen in adults. The available data are insufficient to support the use of famciclovir for the treatment of children 1 to <12 years of age with chickenpox or infections due to HSV for the following reasons:

Chickenpox

The efficacy of famciclovir for the treatment of chickenpox has not been established in either pediatric or adult patients. Famciclovir is approved for the treatment of herpes zoster in adult patients. However, extrapolation of efficacy data from adults with herpes zoster to children with chickenpox would not be appropriate. Although chickenpox and herpes zoster are caused by the same virus, the diseases are different.

Clinical information on genital herpes in children is limited. Therefore, efficacy data from adults cannot be extrapolated to this population. Further, famciclovir has not been studied in children 1 to <12 years of age with recurrent genital herpes. None of the children in Study 2 had genital herpes.

Herpes Labialis

There are no pharmacokinetic and safety data in children 1 to <12 years of age to support a famciclovir dose that provides penciclovir systemic exposures comparable to the penciclovir systemic exposures in adults after a single dose administration of 1500 mg. Moreover, no efficacy data have been obtained in children 1 to <12 years of age with recurrent herpes labialis.

Study 3 was an open-label, single-arm study to evaluate the pharmacokinetics, safety, and antiviral activity of a single 1500 mg dose (three 500 mg tablets) of famciclovir in children 12 to <18 years of age with recurrent herpes labialis. A total of 53 subjects were enrolled in the study; 10 subjects in the pharmacokinetic part of the study and 43 subjects in the non-pharmacokinetic part of the study. All enrolled subjects weighed ≥40 kg. The 43 subjects enrolled in the nonpharmacokinetic part of the study had active recurrent herpes labialis and received a single 1500 mg dose of famciclovir within 24 hours after the onset of symptoms (median time to treatment initiation was 21 hours). The safety profile of famciclovir observed in this study was similar to that seen in adults. The median time to healing of patients with non-aborted lesions was 5.9 days.

In a phase 3 trial in adults in which patients received a single 1500 mg dose of famciclovir or placebo, the median time to healing among patients with non-aborted lesions was 4.4 days in the famciclovir 1500 mg single-dose group and 6.2 days in the placebo group. Of note, in the adult study treatment was initiated by patients within 1 hour after the onset of symptoms . Based on the efficacy results in Study 3, famciclovir is not recommended in children 12 to <18 years of age with recurrent herpes labialis.

Geriatric Use

Of 816 patients with herpes zoster in clinical studies who were treated with FAMVIR, 248 (30.4%) were ≥65 years of age and 103 (13%) were ≥75 years of age. No overall differences were observed in the incidence or types of adverse events between younger and older patients. Of 610 patients with recurrent herpes simplex (type 1 or type 2) in clinical studies who were treated with FAMVIR, 26 (4.3%) were >65 years of age and 7 (1.1%) were >75 years of age. Clinical studies of FAMVIR in patients with recurrent genital herpes did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently compared to younger subjects.

No famciclovir dosage adjustment based on age is recommended unless renal function is impaired . In general, appropriate caution should be exercised in the administration and monitoring of FAMVIR in elderly patients reflecting the greater frequency of decreased renal function and concomitant use of other drugs.

Patients With Renal Impairment

Apparent plasma clearance, renal clearance, and the plasma-elimination rate constant of penciclovir decreased linearly with reductions in renal function. After the administration of a single 500 mg famciclovir oral dose (n=27) to healthy volunteers and to volunteers with varying degrees of renal impairment (CLCR ranged from 6.4 to 138.8 mL/min), the following results were obtained (Table 4):

Table 4 Pharmacokinetic Parameters of Penciclovir in Subjects with Different Degrees of Renal Impairment

In a multiple-dose study of famciclovir conducted in subjects with varying degrees of renal impairment (n=18), the pharmacokinetics of penciclovir were comparable to those after single doses.

A dosage adjustment is recommended for patients with renal impairment .

Patients With Hepatic Impairment

Mild or moderate hepatic impairment (chronic hepatitis , chronic ethanol abuse , or primary biliary cirrhosis ) had no effect on the extent of availability (AUC) of penciclovir following a single dose of 500 mg famciclovir. However, there was a 44% decrease in penciclovir mean maximum plasma concentration (Cmax) and the time to maximum plasma concentration (tmax) was increased by 0.75 hours in patients with hepatic impairment compared to normal volunteers. No dosage adjustment is recommended for patients with mild or moderate hepatic impairment. The pharmacokinetics of penciclovir has not been evaluated in patients with severe hepatic impairment. Conversion of famciclovir to the active metabolite penciclovir may be impaired in these patients resulting in a lower penciclovir plasma concentrations, and thus possibly a decrease of efficacy of famciclovir .

Black And African American Patients

In a randomized, double-blind, placebo-controlled trial conducted in 304 immunocompetent black and African American adults with recurrent genital herpes there was no difference in median time to healing between patients receiving FAMVIR or placebo. In general, the adverse reaction profile was similar to that observed in other FAMVIR clinical trials for adult patients . The relevance of these study results to other indications in black and African American patients is unknown .

Generic Name: famciclovir (fam SYE klo veer)
Brand Names: Famvir

Medically reviewed by P. Thornton, DipPharm Last updated on Jul 4, 2019.

  • Overview
  • Side Effects
  • Dosage
  • Professional
  • Interactions
  • More

The Famvir brand name has been discontinued in the U.S. If generic versions of this product have been approved by the FDA, there may be generic equivalents available.

What is Famvir?

Famvir (famciclovir) is an antiviral drug. It slows the growth and spread of the herpes virus so that the body can fight off the infection. Famciclovir will not cure herpes, but it can lessen the symptoms of the infections.

Famvir is used to treat infections caused by herpes viruses, including genital herpes, cold sores, and shingles.

Famvir is sometimes used in people with human immunodeficiency virus (HIV) who develop herpes outbreaks around the mouth, genitals, or anal area.

Famvir may not be effective in treating your first episode of genital herpes, but may help prevent future episodes. Famciclovir also may not be effective in Black or African-American people with genital herpes, and may not be effective in any person with shingles (herpes zoster) affecting the eyes.

Famvir is used to treat infections caused by herpes viruses, including genital herpes, cold sores, and shingles.

There is no cure for herpes and famciclovir will not prevent you from developing symptoms in the future.

Important Information

You should not take Famvir if you are allergic to famciclovir or penciclovir cream (Denavir). Take this medicine for the full prescribed length of time. Your symptoms may improve before the infection is completely cleared.

Treatment with Famvir should be started as soon as possible after the first appearance of symptoms (such as tingling, burning, blisters).

Herpes infections are contagious and you can infect other people, even while you are being treated with Famvir. Avoid letting infected areas come into contact with other people. Avoid touching an infected area and then touching your eyes. Wash your hands frequently to prevent passing the infection to others.

Before taking this medicine

You should not use Famvir if you are allergic to famciclovir or penciclovir cream (Denavir).

To make sure Famvir is safe for you, tell your doctor if you have ever had:

  • liver disease;

  • kidney disease;

  • a weak immune system;

  • galactose intolerance;

  • severe lactase deficiency; or

  • glucose-galactose malabsorption.

Tell your doctor if you are pregnant or plan to become pregnant. Herpes can be passed to your baby during childbirth if you have a genital lesion when your baby is born. If you have genital herpes, it is very important to prevent herpes lesions during pregnancy. Take your medicine as directed to best control your infection.

If you are pregnant, your name may be listed on a pregnancy registry to track the effects of famciclovir on the baby.

It may not be safe to breast-feed while using this medicine. Ask your doctor about any risk.

Famciclovir is not approved for use by anyone younger than 18 years old.

How should I take Famvir?

Take Famvir exactly as prescribed by your doctor. Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose.

Taking more Famvir than prescribed will not make this medicine more effective

For cold sores or genital herpes, you should start taking Famvir as soon as possible after the first appearance of symptoms (such as tingling, burning, blisters).

You may take Famvir with or without food.

Lesions caused by herpes viruses should be kept as clean and dry as possible. Wearing loose clothing may help to prevent irritation of the lesions.

To prevent recurrent genital herpes, you may need to take Famvir for up to 1 year. Follow your doctor’s instructions.

Use this medicine for the full prescribed length of time, even if your symptoms quickly improve. Skipping doses may increase the risk of your virus becoming resistant to medication.

Store at room temperature away from moisture and heat.

Famvir dosing information

Usual Adult Dose for Herpes Simplex — Mucocutaneous/Immunocompetent Host:

Genital herpes:
Initial episode: 250 mg orally 3 times a day for 7 to 10 days has been recommended by the US Centers for Disease Control and Prevention (CDC)
Recurrent episodes: 1000 mg orally twice a day for 1 day; alternatively, 125 mg orally twice a day for 5 days has been recommended by the CDC
Famciclovir should be started at the first sign or symptom of a recurrent episode (such as tingling, burning, itching, pain, or lesion). The efficacy has not been established if started more than 6 hours after onset of symptoms or lesions.

Usual Adult Dose for Herpes Simplex — Mucocutaneous/Immunocompromised Host:

Recurrent episodes of orolabial or genital herpes in HIV-infected patients: 500 mg orally twice a day for 7 days (5 to 10 days recommended by the CDC)
Famciclovir should be started at the first sign or symptom of a recurrent episode (such as tingling, burning, itching, pain, or lesion). The efficacy has not been established if started more than 48 hours after onset of symptoms or lesions.

Usual Adult Dose for Herpes Simplex — Suppression:

Chronic suppression of recurrent genital herpes:
Immunocompetent patients: 250 mg orally twice a day
HIV-infected patients: 500 mg orally twice a day has been recommended by the CDC
Therapy should be continued as clinically appropriate, although the safety and efficacy of famciclovir therapy beyond 1 year have not been established.

Usual Adult Dose for Herpes Zoster:

500 mg orally every 8 hours for 7 days
Famciclovir is most effective if started within 48 hours of onset of rash. The efficacy has not been established if started more than 72 hours after onset of rash.

Usual Adult Dose for Herpes Simplex Labialis:

Recurrent herpes labialis: 1500 mg orally as a single dose
Famciclovir is most effective if started at the earliest sign or symptom of a cold sore (such as tingling, burning, itching, pain, or lesion).

What happens if I miss a dose?

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while taking Famvir?

Taking this medicine will not prevent you from passing genital herpes to other people. Herpes infections are contagious and you can infect other people even while you are taking Famvir.

Avoid driving or hazardous activity until you know how this medicine will affect you. Your reactions could be impaired.

Avoid sexual intercourse or use a latex condom to help keep you from spreading the virus to others. Avoid letting infected areas come into contact with other people. Avoid touching an infected area and then touching your eyes. Wash your hands frequently to prevent the spread of infection.

Famvir side effects

Get emergency medical help if you have signs of an allergic reaction to Famvir: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

  • confusion; or

  • kidney problems – little or no urination, swelling in your feet or ankles, feeling tired or short of breath.

Common Famvir side effects may include:

  • headache; or

  • nausea.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect Famvir?

Other drugs may interact with famciclovir, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Famvir only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Copyright 1996-2020 Cerner Multum, Inc. Version: 5.01.

Medical Disclaimer

More about Famvir (famciclovir)

  • Side Effects
  • During Pregnancy or Breastfeeding
  • Dosage Information
  • Drug Images
  • Drug Interactions
  • En Español
  • 15 Reviews
  • Generic Availability
  • Drug class: purine nucleosides

Consumer resources

  • Famvir
  • Famvir (Advanced Reading)

Professional resources

  • Famvir (AHFS Monograph)
  • … +1 more

Related treatment guides

  • Cold Sores
  • Herpes Simplex, Mucocutaneous/Immunocompetent Host
  • Herpes Zoster
  • Herpes Simplex, Mucocutaneous/Immunocompromised Host
  • Herpes Simplex, Suppression

SIDE EFFECTS

Acute renal failure is discussed in greater detail in other sections of the label .

The most common adverse events reported in at least 1 indication by >10% of adult patients treated with FAMVIR are headache and nausea.

Clinical Trials Experience In Adult Patients

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared with rates in the clinical trials of another drug and may not reflect the rates observed in practice.

Immunocompetent Patients

The safety of FAMVIR has been evaluated in active-and placebo-controlled clinical studies involving 816 FAMVIR-treated patients with herpes zoster (FAMVIR, 250 mg three times daily to 750 mg three times daily); 163 FAMVIR-treated patients with recurrent genital herpes (FAMVIR, 1000 mg twice daily); 1,197 patients with recurrent genital herpes treated with FAMVIR as suppressive therapy (125 mg once daily to 250 mg three times daily) of which 570 patients received FAMVIR (open-labeled and/or double-blind) for at least 10 months; and 447 FAMVIR-treated patients with herpes labialis (FAMVIR, 1500 mg once daily or 750 mg twice daily). Table 2 lists selected adverse events.

Table 2 Selected Adverse Events (all grades and without regard to causality) Reported by ≥2% of Patients in Placebo-Controlled Famvir Trials*

Table 3 lists selected laboratory abnormalities in genital herpes suppression trials.

Table 3 Selected Laboratory Abnormalities in Genital Herpes Suppression Studies*

HIV-Infected Patients

Postmarketing Experience

The adverse events listed below have been reported during postapproval use of FAMVIR. Because these events are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure:

Blood and lymphatic system disorders: Thrombocytopenia

Hepatobiliary disorders: Abnormal liver function tests, cholestatic jaundice

Immune system disorders: Anaphylactic shock, anaphylactic reaction

Nervous system disorders: Dizziness, somnolence, seizure

Psychiatric disorders: Confusion (including delirium, disorientation, and confusional state occurring predominantly in the elderly), hallucinations

Skin and subcutaneous tissue disorders: Urticaria, erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis, angioedema (e.g., face, eyelid, periorbital, and pharyngeal edema), hypersensitivity vasculitis

Cardiac disorders: Palpitations

Read the entire FDA prescribing information for Famvir (Famciclovir)

Valacyclovir vs. Acyclovir vs. Famciclovir: The Facts

There are several drugs used to treat herpes, all of which are antiviral medications. The most popular, effective and widely used herpes medications currently available are valacyclovir (or Valtrex), acyclovir (or Zovirax) and famciclovir (or Famvir). All of these drugs work through a similar mechanism, and all have their place in treating cases of HSV-1 and HSV-2. In this guide, we’re doing a valacyclovir vs. acyclovir vs. famciclovir—the three most popular and widely used herpes medications—comparison to explain which one is the best choice for treating and managing the virus.

How Do Herpes Drugs Work?

Herpes medications like valacyclovir, acyclovir and famciclovir belong to a class of medications called antiviral drugs.

Antiviral drugs are designed to inhibit the growth and development of viruses in the body. Unlike antibiotics, which eliminate the bacteria that cause infections, antiviral drugs simply control viral proliferation, rather than completely eliminating the target virus from the body.

None of the antiviral drugs on the market today can cure herpes. However, consistent use of an antiviral drug can make living with herpes much easier by speeding up healing after an outbreak and reducing your risk of transmitting the virus to other people.

Herpes drugs are taken for several reasons. People with active HSV-1 or HSV-2 infections can take them during outbreaks to control and treat their symptoms. Antiviral drugs are also used as part of suppressive therapy for herpes to reduce the severity and frequency of outbreaks.

Even people with asymptomatic herpes can benefit from using antiviral drugs by lowering their risk of spreading the virus to other people through sexual or oral contact.

Valacyclovir

Valacyclovir is one of the most widely used drugs for treating herpes. It’s been approved for use as a herpes treatment since 1995 and has a consistent safety record. Most people know of this drug as Valtrex, a brand name used to market the medication by GlaxoSmithKline.

Valacyclovir is a prodrug, meaning it converts into another drug inside the body. After you take a tablet of valacyclovir, it’s converted into the active substance acyclovir. Acyclovir then blocks the herpes virus from reproducing, helping to control the symptoms of a herpes outbreak.

Like other herpes medications, valacyclovir is highly effective. Studies show that it reduces the amount of time required for healing during a herpes outbreak, as well as reducing your risk of transmitting the herpes virus to other people.

Valacyclovir starts working almost as soon as you start taking it. It’s effective against all forms of the herpes virus, but valacyclovir dosage differs depending on whether it’s being used to treat outbreaks of oral herpes, genital herpes or shingles.

The top reason people use valacyclovir vs. acyclovir for cold sores is because of its higher level of oral bioavailability. Acyclovir is almost completely broken down by the liver when taken orally, whereas valacyclovir has an oral bioavailability level of approximately 55 percent.

This means that more of the drug makes it into your body, helping to control a herpes outbreak and reduce your risk of transmitting the virus.

Cheap, effective and readily available, valacyclovir is usually the first medication your doctor will recommend for a herpes outbreak. Our Valacyclovir 101 guide includes more information on this drug, including common dosages, potential side effects, interactions and brand names.

Acyclovir

Acyclovir, or ACV, is an older antiviral medication that’s still commonly used to treat herpes. It’s effective against HSV-1, HSV-2 and shingles. Acyclovir is also used to treat chickenpox and as a preventative treatment against cytomegalovirus.

Acyclovir was discovered in the late 1970s and was widely used as a treatment for herpes for decades. Although it’s still widely available and remains in use today, alternative antiviral drugs like valacyclovir tend to be prescribed more often for long-term herpes management.

When taken orally, valacyclovir converts into acyclovir after it passes through the liver. As such, the effects of acyclovir are the same as valacyclovir—faster recovery during an oral or genital herpes outbreak and a reduced risk of transmitting the virus to other people.

The main reason people choose valacyclovir vs. acyclovir for cold sores because of its improved bioavailability, which allows a lower dose of the drug to be used in treatment. Studies show that a small 500 mg dose of valacyclovir is as effective as a larger 800 mg dose of acyclovir in treating HSV.

Famciclovir is another antiviral drug that’s used for certain herpes infections. Unlike valacyclovir and acyclovir, which are usually prescribed for HSV-1 and HSV-2, famciclovir is typically used to treat shingles, or herpes zoster.

Famciclovir was introduced in the 1990s by Novartis and is sold under as Famvir in the United States. Since 2007, it’s been available as a generic medication at a relatively affordable cost.

Most prescriptions of famciclovir are for shingles, or herpes zoster. The drug is also effective at controlling HSV-1 and HSV-2 symptoms in patients with compromised immune systems and is occasionally used as an alternative to valacyclovir and acyclovir for this purpose.

Which Herpes Medication is Best?

In the war between valacyclovir vs. acyclovir vs. famciclovir, the truth is, there is no “best” herpes medication. All three of the drugs are safe and proven to be effective as treatments for HSV-1, HSV-2, shingles and other forms of the herpes virus.

If you think you might have herpes, the best approach is to speak to your doctor about treatment options. Your doctor will be able to provide advice on the most effective drug for treating herpes based on your symptoms, immune system, lifestyle and overall health.

About famciclovir

Type of medicine An antiviral medicine
Used for Viral infections in adults
Available as Tablets

Famciclovir is used to treat infections caused by two common viruses – herpes zoster and herpes simplex. The herpes zoster virus is the cause of shingles. Herpes simplex viruses cause genital herpes. You will have been prescribed famciclovir to treat either shingles, or genital herpes. Famciclovir works by preventing viruses from multiplying, and this reduces the severity of the infection.

Before taking famciclovir

Some medicines are not suitable for people with certain conditions, and sometimes a medicine can only be used if extra care is taken. For these reasons, before you start taking famciclovir it is important that your doctor knows:

  • If you are pregnant, trying for a baby, or breastfeeding.
  • If you have any problems with the way your liver works, or if you have any problems with the way your kidneys work.
  • If you are taking or using any other medicines. This includes any medicines you are taking which are available to buy without a prescription, as well as herbal and complementary medicines.
  • If you have ever had an allergic reaction to a medicine.

How to take famciclovir

  • Before you start the treatment, read the manufacturer’s printed information leaflet from inside the pack. It will give you more information about famciclovir, and it will also provide you with a full list of the side-effects which you could experience from taking it.
  • Your dose will depend upon the type of infection you have, so take famciclovir exactly as your doctor tells you to. Typically, doses range from 250 mg to 750 mg, and doses are taken either one, two or three times daily. Your doctor or pharmacist will tell you what dose is right for you, and this information will also be printed on the label of the pack to remind you.
  • Space out your doses evenly during the day. You can take famciclovir tablets either with or without food.
  • Even if you feel your infection has cleared up, keep taking the tablets until the course is finished (unless your doctor tells you to stop sooner). This is to prevent the infection from coming back. A course of treatment usually lasts for around 5-10 days, although some people need to take famciclovir for only one day, and other people need a course lasting for several months. If you still feel unwell after finishing your course of treatment, go back to see your doctor.
  • If you forget to take a dose, take it as soon as you remember and then continue as before. Try to take the correct number of doses each day, but do not take two doses at the same time to make up for a missed dose.

Getting the most from your treatment

  • If you have been prescribed famciclovir for genital herpes, do not have sex while you have sores or blisters. Even after these have healed, there is still a small chance that you may pass on the virus when you have sex – using a condom reduces this risk.
  • If you are having an operation or any other medical treatment, tell the person carrying out the treatment that you are taking famciclovir.

Can famciclovir cause problems?

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the more common ones associated with famciclovir. The best place to find a full list of the side-effects which can be associated with your medicine, is from the manufacturer’s printed information leaflet supplied with the medicine. Alternatively, you can find an example of a manufacturer’s information leaflet in the reference section below. Speak with your doctor or pharmacist if any of the following continue or become troublesome.

Very common famciclovir side-effects (these affect more than 1 in 10 people) What can I do if I experience this?
Headache Drink plenty of water and ask your pharmacist to recommend a suitable painkiller. If the headaches continue, speak with your doctor
Common famciclovir side-effects (these affect less than 1 in 10 people) What can I do if I experience this?
Feeling sick (nausea) or being sick (vomiting), diarrhoea, stomach ache Stick to simple foods – avoid fatty or spicy meals
Itchy rash If this becomes troublesome, speak with your doctor
Feeling dizzy Do not drive and do not use tools or machines while affected

If you experience any other symptoms which you think may be due to the medicine, speak with your doctor or pharmacist for further advice.

How to store famciclovir

  • Keep all medicines out of the reach and sight of children.
  • Store in a cool, dry place, away from direct heat and light.

Important information about all medicines

Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital. Take the container with you, even if it is empty.

This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.

If you buy any medicines, check with a pharmacist that they are suitable to take with your other medicines.

Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.

If you have any questions about this medicine ask your pharmacist.

FAMCICLOVIR 500MG TABLETS

Famvir® 500 mg Tablets
2438
01.05.15
(famciclovir)
PATIENT INFORMATION LEAFLET
Your medicine is available using the above name but will be referred to as
Famvir throughout this leaflet.
Famvir is also available in 125 mg and 250 mg strength.
Pregnancy, breast-feeding and fertility
If you are pregnant or breast feeding, think you may be pregnant or are
planning to have a baby, ask your doctor for advice before taking this
medicine. Famvir is not to be used during pregnancy unless clearly
necessary. Your doctor will discuss with you the potential risks of taking
Famvir during pregnancy.
Famvir is not to be used during breast-feeding unless clearly necessary.
Your doctor will discuss with you the possible risks of taking Famvir during
breast-feeding.
Read all of this leaflet carefully before you start taking this medicine
because it contains important information for you.
– Keep this leaflet. You may need to read it again.
– If you have any further questions, ask your doctor or pharmacist.
– Famvir has been prescribed for you only. Do not pass it on to others. It
may harm them, even if their signs of illness are the same as yours.
– If you get any side effects, talk to your doctor or pharmacist. This
includes any possible side effects not listed in this leaflet. See section 4.
Driving and using machines
Famvir can cause dizziness, drowsiness or confusion. Do not drive or use
machines if you have any of these symptoms while taking Famvir.
What is in this leaflet:
1. What Famvir is and what it is used for
2. What you need to know before you take Famvir
3. How to take Famvir
4. Possible side effects
5. How to store Famvir
6. Contents of the pack and other information
3. HOW TO TAKE FAMVIR
Always take this medicine exactly as your doctor has told you. Check with
your doctor or pharmacist if you are not sure.
– The daily dose and length of treatment will depend on the type of viral
infection you have – see below. Your doctor will prescribe the correct
dose for you.
– For the best results start the medicine as soon as possible after the first
signs and symptoms appear.
– Do not have sexual contact with anyone if you have symptoms of genital
herpes – even if you have started treatment with Famvir. This is
because you could pass the herpes infection to your partner.
– If you have or have had kidney problems, your doctor may decide to
give you a lower dose of Famvir.
1. WHAT FAMVIR IS AND WHAT IT IS USED FOR
Famvir is an antiviral medicine. It stops the infecting virus from reproducing.
Since the virus reproduces very early in the infection, you will benefit most
from treatment if you take Famvir as soon as the first symptoms appear.
Famvir is used to treat two types of viral infections in adults:
– Shingles (herpes zoster), which is a viral infection caused by a virus
called varicella zoster (the same virus that causes chickenpox). Famvir
stops the virus from spreading in the body so that healing can occur
faster.
– Famvir is also used for the treatment of shingles in the area around the
eye or of the eye itself (ophthalmic zoster).
– Genital herpes. Genital herpes is a viral infection caused by herpes
simplex virus type 1 or 2. It is normally spread by sexual contact. It
causes blisters and burning or itching around the genitals, which may be
painful. Famvir is used to treat genital herpes infections in adults.
People who have frequent episodes of genital herpes can also take
Famvir to help to prevent the attacks.
2. WHAT YOU NEED TO KNOW BEFORE YOU TAKE FAMVIR
Do not take Famvir
– If you are allergic to famciclovir, to any of the other ingredients of this
medicine (listed in section 6), or to penciclovir (the active metabolite of
famciclovir and an ingredient of some other medicines).
Ask your doctor for advice, if you think you may be allergic.
Warnings and precautions
Talk to your doctor before taking Famvir
– If you have kidney problems (or have had them before). Your doctor
may decide to give you a lower dose of Famvir.
– If you have problems with your body’s immune system.
– If you have liver problems.
If any of these applies to you, tell your doctor before you take Famvir.
Children and adolescents (below the age of 18 years)
Famvir is not recommended for use in children and adolescents.
Prevent passing genital herpes to others
If you are taking Famvir to treat or to suppress genital herpes, or you have
had genital herpes in the past, you should still practise safe sex, including
the use of condoms. This is important to prevent you passing the infection
on to others. You should not have sex if you have genital sores or blisters.
Other medicines and Famvir
Tell your doctor or pharmacist if you are taking, have recently taken or
might take any other medicines, including medicines obtained without a
prescription.
It is especially important that you tell your doctor or pharmacist if you are
taking any of the following medicines:
– Raloxifen (used to prevent and treat osteoporosis).
– Probenecid (used to treat high blood levels of uric acid associated with
gout and to increase blood levels of penicillin-type antibiotics), or any
other medicine that can affect your kidneys.
Famvir with food and drink
You can take Famvir with or without food.
Famvir contains lactose
If you have been told by your doctor that you have an intolerance to some
sugars, e.g. lactose, contact your doctor before taking this medicine
(Famvir 125 mg and 250 mg tablets only).
Dose for shingles
If you have a normal immune system, the recommended dose is
– 500 mg, three times a day, for seven days
If you have a reduced immune system, the recommended dose is
– 500 mg three times a day, for ten days.
Dose for genital herpes
The dose depends on the state of your immune system, and the stage of
your infection.
If you have a normal immune system, the doses are as follows:
For the first outbreak, the recommended dose is:
– 250 mg three times a day, for five days.
To treat further outbreaks, the recommended dose is:
– 125 mg twice a day, for five days.
To prevent future outbreaks, the recommended dose is:
– 250 mg twice a day.
Your doctor will tell you how long you need to continue taking your tablets.
If you have a reduced immune system, the doses are as follows:
To treat the current outbreak, the recommended dose is:
– 500 mg twice a day, for seven days.
To prevent future outbreaks, the dose is
– 500 mg twice a day.
Your doctor will tell you how long you need to continue taking your tablets.
If you take more Famvir than you should
If you have taken more tablets than you have been told to take, or if
someone else accidentally takes your medicine, go to your doctor or
hospital for advice immediately. Show them your pack of tablets.
Taking too much Famvir may affect the kidneys. In people who already
have kidney problems it may, rarely, lead to kidney failure if their dose is
not correctly lowered.
If you forget to take Famvir
If you forget to take a dose of Famvir, you should take it as soon as you
remember. Then take your next dose as scheduled. However, do not take
two doses within a time interval of less than 1 hour, in that case you should
skip the missed dose. Furthermore, do not take a double dose to make up
for a forgotten dose.
If you have any further questions on the use of this medicine, ask your
doctor or pharmacist.
4. POSSIBLE SIDE EFFECTS
Like all medicines, this medicine can cause side effects, although not
everybody gets them.
Serious side effects of Famvir are:
Most of these side effects are rare or uncommon (they affect between 1 to
100 in every 10,000 patients)
– Severe blistering of the skin or mucous membranes of the lips, eyes,
mouth, nasal passages or genitals (these could be signs of a serious
allergic skin reaction).
– Unexplained bruising, reddish or purplish patches on the skin or
nosebleeds (these could be signs of a decrease in the number of blood
platelets).
– Swelling below the surface of the skin (e.g. facial swelling, swelling
around eye, eyelid swelling, throat swelling).
– Yellowing of the skin and/or eyes (signs of jaundice).
– Purple skin patches, itching, burning (signs of inflamed blood
vessels).
Contact a doctor or go to the emergency department at your nearest
hospital straight away if you get any of these effects.
Very common side effects (these side effects affect more than 1 in 10
people)
– Headache
Common side effects (these side effects affect up to 1 in 10 people)
– Feeling sick (nausea)
– Vomiting
– Abdominal pain
– Diarrhoea
– Dizziness
– Rash
– Itching
– Liver function test giving abnormal results
Uncommon side effects (these side effects affect up to 1 in 100 people)
– Confusion
– Drowsiness (usually in older people)
– Itchy rash (urticaria)
Rare side effects (these side effects affect up to 1 in 1,000 people)
– Hallucinations (seeing or hearing things that are not really there)
– Palpitations (signs of abnormal heart beat)
Reporting of side effects
If you get any side effects, talk to your doctor, pharmacist or nurse. This
includes any possible side effects not listed in this leaflet. You can also
report side effects directly via the Yellow Scheme at:
www.mhra.gov.uk/yellowcard. By reporting side effects you can help
provide more information on the safety of this medicine.
5. HOW TO STORE FAMVIR
Keep all medicines out of the sight and reach of children.
Do not store above 30ºC. Store in the original package.
Do not take the tablets after their expiry date which is printed on the outside
of the pack.
If the medicines become discoloured or show any other signs of
deterioration, consult your pharmacist who will tell you what to do.
Medicines should not be disposed of via wastewater or household waste.
Ask you pharmacist how to dispose of medicine no longer required. These
measures will help to protect the environment.
6. CONTENTS OF THE PACK AND OTHER INFORMATION
What Famvir contains
The active ingredient in your tablets is called famciclovir.
Each film-coated tablet contains 500mg famciclovir.
The tablets also contain hydroxypropyl cellulose, sodium starch glycollate,
magnesium stearate, hypromellose, macrogol 4000, macrogol 6000 and
titanium dioxide (E171).
What Famvir looks like and contents of the pack
Famvir tablets are white, oval, biconvex film-coated tablets, marked ‘FV500’
on one side and plain on other side.
Available in packs of 14, 21, 28 and 56 tablets.
MANUFACTURER AND PRODUCT LICENCE HOLDER
Manufactured by
Novartis Farmaceutica S.A., Ronda Santa Maria, 158- Barbera Del VallesBarcelona, Spain.
Novartis Farma S.p.A., Via Provinciale Schito, 131-80058 Torre Annunziata
(NA), Italy.
Procured from within the EU by Product Licence holder
Star Pharmaceuticals Ltd, 5 Sandridge Close, Harrow, Middlesex HA1 1XD.
Repackaged by Servipharm Ltd.
POM
PL 20636/2438
Leaflet revision issue date (Ref) 01.05.15
Famvir is trademark of Novartis AG.

About the author

Leave a Reply

Your email address will not be published. Required fields are marked *