Famvir, 250 mg 21 pcs

Famvir is an antiviral drug. After oral administration, penciclovir is rapidly converted to penciclovir, which has activity against human herpes viruses, including Varicella zoster (herpes zoster virus) and Herpes simplex virus types 1 and 2 (labial and genital herpes virus), as well as Epstein-Barr virus and cytomegalovirus.

Penciclovir enters virus-infected cells where it is rapidly converted into monophosphate by viral thymidine kinase, which in turn is converted into triphosphate with the help of cellular enzymes. Penciclovir triphosphate stays in virus-infected cells for more than 12 hours, suppressing viral DNA replication.

The concentration of penciclovir triphosphate in uninfected cells does not exceed the minimum detectable, so in therapeutic concentrations penciclovir has no effect on uninfected cells.

Penciclovir is active against recently discovered acyclovir-resistant strains of Herpes simplex virus with an altered DNA polymerase.

The incidence of resistance to famiclovir (penciclovir) does not exceed 0.3%, in patients with compromised immunity – 0.19%.
Resistance was detected at the beginning of treatment and did not develop during treatment or after completion of therapy. Famcyclovir has been shown to significantly reduce the severity and duration of post-herpetic neuralgia in patients with herpes zoster.
In immunocompromised patients due to HIV infection, famcyclovir at a dose of 500 mg twice daily has been shown to reduce the number of days of herpes simplex virus excretion (both with and without clinical manifestations).

Pharmacokinetics

Intake
After oral administration, famcyclovir is quickly and almost completely absorbed and rapidly converted to active penciclovir. Bioavailability of pencyclovir after oral administration of Famvir is 77%. Cmax of pencyclovir after oral administration with doses of 125 mg, 250 mg or 500 mg of Famciclovir is reached in 45 minutes on average and is 0.8 µg/ml, 1.6 µg/ml and 3.3 µg/ml, respectively.

Distribution
Pharmacokinetic curves “concentration – time” coincide with a single dose of famcyclovir and when dividing the daily dose into 2 or 3 doses.

The binding to plasma proteins of penciclovir and its 6-deoxy precursor is less than 20%.
No cumulation was noted with repeated doses of the drug.

Excretion
T1/2 of pencyclovir from plasma in the terminal phase after single and repeated doses is about 2 hours.

Famcyclovir is excreted mainly in the form of penciclovir and its 6-deoxy precursor, which are excreted unchanged in the urine; famcyclovir is not detected in the urine.

Indications

Active ingredient

Composition

Active ingredient:

famcyclovir 250 mg.

Auxiliary substances:

hydroxypropylcellulose,

anhydrous lactose,

polyethylene glycol 6000 (macrogol).

How to take, the dosage

The drug is taken orally, regardless of meals, without chewing, with water.

Infections caused by Varicella zoster virus in patients with normal immunity: The recommended dose is 250 mg 3 times/day, or 500 mg 2 times/day, or 750 mg once/day, for 7 days (acute phase of disease). In ophthalmoherpes, the recommended dose is 500 mg 3 times/day for 7 days. To reduce the duration and frequency of postherpetic neuralgia, the recommended dose is 250-500 mg 3 times/day for 7 days.

Infections caused by Varicella zoster virus in immunocompromised patients: the recommended dose is 500 mg 3 times daily for 10 days.

Infections caused by Herpes simplex virus types 1 and 2 in patients with normal immunity: In primary infection, the recommended dose is 250 mg 3 times/day for 5 days. Treatment should be started as soon as possible, immediately after the appearance of the first symptoms of the disease. In relapses of chronic infection adults are prescribed 125 mg 2 times per day for 5 days. Treatment should be started as early as in the prodromal period or immediately after the onset of symptoms.

Infections caused by Herpes simplex virus types 1 and 2 in immunocompromised patients: The recommended dose is 500 mg 2 times per day for 7 days. Treatment should be started as soon as possible, immediately after the appearance of the first symptoms of the disease. As a suppressive therapy of recurrent herpes infection, 250 mg 2 times per day is prescribed. The duration of therapy depends on the severity of the disease. Periodic discontinuation of therapy every 12 months is recommended to assess possible changes in disease course. In HIV-infected patients, the effective dose is 500 mg 2 times per day.

Elderly patients: The dosing regimen of famcyclovir does not change if renal function is preserved.

In patients with impaired renal function there is a decrease in clearance of penciclovir. Adequate adjustment of the dosing regimen according to the CK is recommended:

Infections caused by Varicella zoster virus (regardless of the patient’s immune status) (CK (ml/min/1.73 m.s.) – dosing regimen:) ≥40 – 250 mg/500 mg 2 times/day or 500 mg 2 times/day, 30-39 – 250 mg 2 or 3 times/day, 10-29 – 125 mg 2 or 3 times/day.

Infections caused by Herpes simplex virus in patients with normal immunity (CK (ml/min/1.73 m.s.)-dosing regimen): first episode: ≥30 to 250 mg 3 times/day, 10-29 to 125 mg 3 times/day; recurrent infection: ≥10 to 125 mg 3 times/day.

Infections caused by Herpes simplex virus in immunocompromised patients (CK (ml/min/1.73 m.s.)-dosing regimen:) ≥40 – 500 mg 2 times/day, 30-39 – 250 mg 2 times/day, 10-29 – 125 mg 2 times/day.

Suppressive therapy for recurrent herpetic infection (CK (ml/min/1.73 m.s.)-dosing regimen): ≥30 – 250 mg 2 times/day, 10-29 – 125 mg 2 times/day.

Patients with renal impairment who are on hemodialysis: Since after 4 hours of hemodialysis the plasma concentration of penciclovir decreases by approximately 75%, the drug should be taken immediately after the hemodialysis procedure. The recommended dose is 250 mg (for patients with herpes zoster) and 125 mg (for patients with genital herpes).

Patients with hepatic impairment do not require dose adjustment.

Interaction

No clinically significant pharmacokinetic interaction of famcyclovir with other drugs was observed.

No effect of famcyclovir on cytochrome P450 system was found.

Drugs that block tubular secretion may increase the concentration of penciclovir in plasma.

In the conducted clinical studies no interaction of zidovudine and famcyclovir was noted when they are taken together.

Special Instructions

The treatment should be started as soon as the diagnosis is established. Caution should be exercised when treating patients with impaired renal function, which may require dosing regimen adjustment. Special precautions in elderly patients are not required. Genital herpes is a sexually transmitted disease.

The risk of infection increases during relapses. In the presence of clinical manifestations of the disease, even if antiviral treatment is started, patients should avoid sexual contact. During maintenance treatment with antivirals, the frequency of viral infection is considerably reduced, but the risk of transmission is theoretically present. Therefore, patients should take appropriate protective measures during sexual contact.

The drug tablets 125 mg, 250 mg, and 500 mg contain lactose (26.9 mg, 53.7 mg, and 107.4 mg, respectively). Famvir should not be used in patients with rare hereditary disorders associated with galactose intolerance, severe lactase deficiency or glucose-galactose malabsorption.

The tolerated doses of Famvir and duration of treatment. Famvir was well tolerated in treatment of infection caused by Varicella zoster virus when administered at a dose of 750 mg 3 times daily for 7 days; in patients with genital herpes when administered at a dose of up to 750 mg 3 times daily for 5 days and at a dose of up to 500 mg 3 times daily for 10 days.

The drug was also shown to be well tolerated when taken 250 mg 3 times/day for 12 months for the treatment of genital herpes. Famvir was well tolerated in immunocompromised patients when treating infections caused by Varicella zoster virus when given 500 mg 3 times/day for 10 days, and infections caused by Herpes simplex viruses when given up to 500 mg 2 times/day for 7 days or 500 mg 2 times/day for 8 weeks.

Pediatric use:

The efficacy and safety of Famvir in children has not been established. Thus, the use of Famciclovir in children is not recommended unless the expected benefits of treatment justify the potential risks associated with the use of the drug.

Impact on the ability to drive and operate machinery:

Famvir is not expected to affect patients’ ability to drive or operate machinery, but patients who experience dizziness, somnolence, confusion or other CNS disturbances while using Famvir should refrain from driving or operating machinery while using the drug.

Contraindications

Hypersensitivity; hypersensitivity to penciclovir.

Side effects

Clinical studies have shown good tolerability of Famvir, including in immunocompromised patients. Headache and nausea have been reported, but these were mild to moderate in frequency in patients receiving placebo.

The following are adverse reactions and their frequency of occurrence based on spontaneous reports as well as cases described in the literature for the entire period in which Famvir is used in clinical practice. The adverse events reported in clinical studies in immunocompromised patients were consistent with those reported in patients with normal immunity.

The following criteria were used to assess the incidence of adverse reactions: very common (> 1/10); common (> 1/100, < 1/10); sometimes (> 1/1000, 1/10000, < 1/1000); very rare (< 1/10000), including individual reports.

Hematopoietic system disorders: very rare – thrombocytopenia.

CNS disorders: rare – headache, confusion (mainly in elderly patients); very rare – dizziness, somnolence (mainly in elderly patients), hallucinations.

The digestive system: rarely – nausea; very rarely – vomiting, jaundice.

Dermatological reactions: very rare – rash, itching, severe skin reactions.

Allergic reactions: very rare – urticaria, severe skin reactions (including erythema multiforme).

Overdose

Described cases of overdose (10.5 g) of Famvir were not accompanied by clinical manifestations.

Treatment: conducting symptomatic and supportive therapy. If the recommendations to reduce the dose of famcyclovir are not followed, taking into account renal function, cases of acute renal failure have been reported in patients with renal disease.

Penciclovir is excreted by hemodialysis.

Penciclovir plasma concentrations are reduced by 75% after hemodialysis for 4.

Pregnancy use

Since the safety of Famvir in pregnant and breastfeeding women has not been studied, its use in pregnancy and lactation is not recommended unless the possible benefits of treatment exceed the potential risks.

It is not known whether pencyclovir is excreted with breast milk in humans. Famiclovir has no pronounced effect on the spermogram, morphology or motility of human sperm.

In experimental studies no embryotoxic and teratogenic effects of famcyclovir and penciclovir were found.

Studies on rats in which famcyclovir was administered orally showed that penciclovir was excreted with breast milk.

Decreased fertility was noted in an experimental model in male rats receiving famcyclovir at a dose of 500 mg/kg body weight, in female rats no pronounced reduction in fertility was noted.

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