Famvir
Generic Name: Famciclovir
Brand Name: Famvir
Indications
Famvir (famciclovir) is indicated for the treatment of acute herpes zoster (shingles). It is also indicated for treatment or suppression of recurrent genital herpes in immunocompetent patients, treatment of recurrent herpes labialis (cold sores) in immunocompetent patients and treatment of recurrent mucocutaneous herpes simplex infections in HIV-infected patients.
Dosage and Administration
Famvir is available for oral administration as 125mg, 250mg and 500mg tablets.
Normal Dosage
Herpes Zoster: The recommended dosage is 500 mg every 8 hours for 7 days. Therapy should be initiated promptly as soon as herpes zoster is diagnosed. No data are available on efficacy of treatment started greater than 72 hours after rash onset.
Herpes Simplex Infections: Recurrent genital herpes: The recommended dosage is 1000 mg twice daily for 1 day. Initiate therapy at the first sign or symptom if medical management of a genital herpes recurrence is indicated. The efficacy of Famvir (famciclovir) has not been established when treatment is initiated more than 6 hours after onset of symptoms or lesions.
Suppression of recurrent genital herpes: The recommended dosage is 250 mg twice daily for up to 1 year. The safety and efficacy of Famvir therapy beyond 1 year of treatment have not been established.
Recurrent herpes labialis (cold sores): The recommended dosage is 1500 mg as a single dose. Initiate therapy at the earliest sign or symptom of a cold sore (e.g. tingling, itching or burning).
HIV-Infected Patients; For recurrent orolabial or genital herpes simplex infection, the recommended dosage is 500 mg twice daily for 7 days.
Overdose: Symptoms of an over dose of this drug include- seizures, and hallucinations.
Drug Description
Famvir (famciclovir) contains famciclovir, an orally administered prodrug of the antiviral agent penciclovir. Chemically, famciclovir is known as 2-[2-(2-amino-9H-purin-9-yl)ethyl]- 1,3-propanediol diacetate. Its molecular formula is C14H19N504; its molecular weight is 321.3. It is a synthetic acyclic guanine derivative and has the following structure
Famciclovir is a white to pale yellow solid. It is freely soluble in acetone and methanol, and sparingly soluble in ethanol and isopropanol. At 25°C famciclovir is freely soluble (> 25% w/v) in water initially, but rapidly precipitates as the sparingly soluble (2%-3% w/v) monohydrate. Famciclovir is not hygroscopic below 85% relative humidity. Partition coefficients are: octanol/water (pH 4.8) P=1.09 and octanol/phosphate buffer (pH 7.4) P=2.08.
Side Effects
The following are some of the side effects that are known to be associated with this medicine. Because a side effect is stated here, it does not mean that all people using this medicine will experience that or any side effect.
- Headache
- Nausea and vomiting
- Rash
- Confusion
- False perceptions of things that are not really there (hallucinations)
- Dizziness
Precautions
- This medicine should be used with caution during pregnancy, and only if the expected benefit to the mother is greater than any possible risk to the foetus. Seek medical advice from your doctor.
- The safety of this medicine during breastfeeding has not been established. Seek medical advice from your doctor.
- Herpes infections are contagious and you can infect other people, even during treatment. Avoid letting infected areas come into contact with other people. Wash your hands frequently to prevent transmission.
- Will not prevent the spread of genital herpes. Avoid sexual intercourse or use a latex condom to prevent spreading the virus to others.
Drug Interactions
- Probenecid (Benemid) may increase the effects of this medication and lead to dangerous side effects. You may need a dosage adjustment or special monitoring during treatment if you are taking probenecid.
- Drugs other than probenecid may also interact. Talk to your doctor before taking any prescription or over-the-counter medicines,which include vitamins,minerals and medicines prescribed by other doctors.
