Favirox tablets 500mg, No. 21

• Varicella zoster virus infections (shingles, including herpes zoster with ocular complications);

• infections caused by the Herpes simplex virus (primary infection, exacerbation of chronic infection, suppression of recurrent infection).

Treatment should begin immediately after diagnosis.

When taken orally, a single dose is 250-500 mg. The frequency and duration of use depend on the indications, the state of immunity, kidney function, and the effectiveness of treatment.

White film-coated tablets, round, biconvex.

1 tab.

famciclovir 125 mg

'-' 250 mg

'-' 500 mg

Excipients: pregelatinized starch - 18.7 mg, microcrystalline cellulose - 11 mg, croscarmellose sodium - 10.2 mg, sodium lauryl sulfate - 1.7 mg, colloidal anhydrous silicon dioxide - 1.7 mg, stearic acid - 1.7 mg.

Hypersensitivity to famciclovir and penciclovir.

pharmachologic effect

Antiviral agent.

After oral administration, famciclovir is rapidly converted in vivo to penciclovir, which has in vivo and in vitro activity against human herpes viruses, including Varicella zoster and Herpes simplex types 1 and 2, as well as Epstein-Barr virus and cytomegalovirus. Penciclovir enters the cells infected with the virus, where, under the action of viral thymidine kinase, it quickly turns into monophosphate, which in turn, with the participation of cellular enzymes, is converted into triphosphate. Penciclovir triphosphate is in the cells infected with viruses for more than 12 hours, suppressing the synthesis of viral DNA and viral replication in them. The half-life of penciclovir triphosphate in cells affected by Varicella zoster, Herpes simplex is 9, 10 and 20 hours, respectively. The concentration of penciclovir triphosphate in uninfected cells does not exceed the minimum detectable,therefore, at therapeutic concentrations, penciclovir has no effect on uninfected cells. Penciclovir is active against recently discovered acyclovir-resistant strains of the Herpes simplex virus with altered DNA polymerase. Famciclovir significantly reduces the intensity and duration of postherpetic neuralgia in patients with herpes zoster. In a placebo-controlled study in patients with immunodeficiency due to HIV infection, it was shown that famciclovir at a dose of 500 mg 2 times / day reduced the number of days of isolation of the Herpes simplex virus (both with and without clinical manifestations).Famciclovir significantly reduces the intensity and duration of postherpetic neuralgia in patients with herpes zoster. In a placebo-controlled study in patients with immunodeficiency due to HIV infection, it was shown that famciclovir at a dose of 500 mg 2 times / day reduced the number of days of isolation of the Herpes simplex virus (both with and without clinical manifestations).Famciclovir significantly reduces the intensity and duration of postherpetic neuralgia in patients with herpes zoster. In a placebo-controlled study in patients with immunodeficiency due to HIV infection, it was shown that famciclovir at a dose of 500 mg 2 times / day reduced the number of days of isolation of the Herpes simplex virus (both with and without clinical manifestations).

Pharmacokinetics

After oral administration, famciclovir is rapidly and almost completely absorbed and rapidly converted to active penciclovir. The bioavailability of penciclovir after oral administration of famciclovir is 77%. At doses of 125 mg, 250 mg or 500 mg of famciclovir, the Cmax of penciclovir is reached after an average of 45 minutes. With repeated doses of the drug, cumulation was not observed. Plasma protein binding of penciclovir and its 6-deoxy precursor is less than 20%. T1 / 2 of penciclovir from plasma in the final phase after taking a single and repeated doses is about 2 hours. Famciclovir is excreted mainly in the form of penciclovir and its 6-deoxy precursor, which are excreted in the urine unchanged; famciclovir is not detected in urine.

Side effect

Possible: mild to moderate headaches, nausea. Rarely: vomiting, dizziness, skin rash; mainly in elderly patients - confusion, hallucinations. In patients with reduced immunity: possible abdominal pain, fever; rarely - granulocytopenia and thrombocytopenia.

Application during pregnancy and lactation

Since the safety of famciclovir during pregnancy and lactation has not been studied, its use is not recommended unless the expected benefit of therapy to the mother outweighs the potential risk to the fetus or infant. It is not known whether penciclovir is excreted in human breast milk. Famciclovir does not have a pronounced effect on spermogram, morphology or motility of human sperm. In experimental studies, no embryotoxic and teratogenic effects of famciclovir and penciclovir were detected. Studies in rats receiving oral famciclovir have shown that penciclovir is excreted in breast milk. A decrease in fertility was noted in an experimental model in male rats receiving famciclovir at a dose of 500 mg / kg body weight; in female rats, no pronounced decrease in fertility was noted.

Application for impaired renal function

Use with caution in patients with impaired renal function.

special instructions

Use with caution in patients with impaired renal function. In the presence of clinical manifestations of genital herpes, even if antiviral treatment is started, patients should avoid sexual intercourse.

Drug interactions

Probenecid and other drugs that affect kidney function can alter plasma levels of penciclovir.