Familar pills 250mg №21

Mechanism of action

Antiviral agent. After oral administration, famciclovir in vivo is rapidly transformed into penciclovir, which has in vivo and in vitro activity against human herpes viruses, including the Varicella zoster and Herpes simplex types 1 and 2 viruses, as well as Epstein-Barr virus and the cytomegalovirus.

Penciclovir enters the virus-infected cells, where under the action of viral thymidine kinase quickly turns into monophosphate, which in turn, with the participation of cellular enzymes, goes into triphosphate. Penciclovir triphosphate is found in virus-infected cells for more than 12 hours, inhibiting viral DNA synthesis and viral replication. 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, in therapeutic concentrations, penciclovir does not affect uninfected cells.

Penciclovir is active against newly 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, famciclovir at a dose of 500 mg 2 times / day reduced the number of days for isolation of the Herpes simplex virus (with or without clinical manifestations).

After ingestion, famciclovir is rapidly and almost completely absorbed and quickly becomes active penciclovir. The bioavailability of penciclovir after oral administration of famciclovir is 77%. At doses of famciclovir 125 mg, 250 mg or 500 mg C_max Penciclovir is reached on average after 45 minutes.

With repeated doses of the drug cumulation is not observed. The plasma protein binding of penciclovir and its 6-deoxy precursor is less than 20%.

T_1/2 penciclovir from plasma in the final phase after administration of single and repeated doses is about 2 hours.

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

Indications and usage

Infection caused by the virus Varicella zoster (shingles, including shingles with ocular complications); Herpes simplex infections (primary infection, exacerbation of chronic infection, suppression of recurrent infection).

Treatment should begin immediately after diagnosis.

When ingested a single dose - 250-500 mg. The frequency and duration of use depend on the evidence, immune status, renal function, treatment effectiveness.

Adverse reactions

Possible: mild to moderate headaches, nausea.

Seldom: vomiting, dizziness, skin rash; primarily in elderly patients - confusion, hallucinations.

In patients with reduced immunity: possible abdominal pain, fever; rarely - granulocytopenia and thrombocytopenia.

Contraindications

Hypersensitivity to famciclovir and penciclovir.

Use during pregnancy and lactation

Since the safety of famciclovir during pregnancy and lactation has not been studied, the use is not recommended, unless the expected benefit of therapy for 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 the spermogram, morphology, or motility of human sperm.

In experimental studies, no embryotoxic and teratogenic effects of famciclovir and penciclovir were detected.

Studies on rats fed famciclovir orally 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, and in female rats there was no marked decrease in fertility.

Application for violations of kidney function

Use with caution in patients with impaired renal function.

Special notes

Use with caution in patients with impaired renal function.

In the presence of clinical manifestations of genital herpes, even in the event of the start of antiviral treatment, patients should avoid sexual intercourse.

Drug Interactions

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