Famvir is an antiviral drug intended for the treatment of infections caused by herpes viruses. The drug effectively inhibits the reproduction of viruses, such as herpes simplex virus (HSV) and varicella-zoster virus (causative agent of shingles), reducing the duration of symptoms and accelerating the healing of affected tissues. Its action is based on blocking viral DNA polymerase, which makes Famvir an important tool in the therapy of acute and recurrent herpetic infections, including genital herpes and ophthalmic herpes. The drug is well tolerated and is suitable for patients with normal and compromised immune systems.
no RX
Dosage | Package | Per Item | Per Pack | Order |
250 mg |
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The trade name of the drug is Famvir. This is the registered name under which the drug is known in medical practice and is available in pharmacies.
The international nonproprietary name is famciclovir. It denotes the active active ingredient and is used in pharmacology internationally.
Famvir is available as film-coated tablets with dosages of 125 mg, 250 mg and 500 mg. Tablets have white color, round or oval shape (depending on the dosage) and are packed in blisters of 7, 10 or 21 pieces. This form provides accurate dosing and convenience of use for patients of all age groups, where the drug is authorized for use.
The main active ingredient is famciclovir. One tablet contains 125 mg, 250 mg or 500 mg of famciclovir, depending on the dosage.
The tablets include substances such as lactose monohydrate, microcrystalline cellulose, croscarmellose sodium, magnesium stearate, and a coating of hypromellose, titanium dioxide, and polyethylene glycol. These components ensure stability, solubility and convenience of the drug.
Famziclovir, the active substance of Famvir, is a prodrug, which in the body is converted into penciclovir - a potent inhibitor of viral DNA polymerase. After oral administration, famciclovir is rapidly metabolized in the liver and intestinal mucosa to penciclovir, which penetrates into infected cells. Within cells, penciclovir is phosphorylated by viral thymidine kinase to the active form, penciclovir triphosphate. This form competitively blocks DNA polymerase of herpes viruses, preventing viral DNA elongation and, consequently, virus replication.
The drug is highly selective to viral enzymes, minimally affecting human cellular DNA polymerases, which reduces its toxicity. Famvir is active against herpes simplex virus types 1 and 2 (HPV-1, HPV-2), varicella-zoster virus (VZV) and to a lesser extent against Epstein-Barr virus and cytomegalovirus. The therapeutic effect is manifested by shortening the duration of rashes, reducing pain and accelerating the healing of lesions. Maximum efficacy is achieved when treatment is started in the first 24-48 hours after the onset of symptoms.
Famziclovir is rapidly absorbed from the gastrointestinal tract after oral administration. The maximum concentration of penciclovir in plasma is reached in 0.5-1 hour, and bioavailability is about 77%. Food intake slows down the rate of absorption, but does not affect the overall degree of absorption, which allows taking the drug regardless of food.
Penciclovir weakly binds to plasma proteins (less than 20%). The volume of distribution is about 1.1 L/kg, indicating penetration into tissues, including skin, mucous membranes and nervous system. The drug concentrates in infected cells, where its active form accumulates for 10-20 hours, providing prolonged action.
Famciclovir is metabolized in the liver and intestinal wall with the participation of aldehyde oxidase enzymes to penciclovir. About 60-65% of the administered dose is converted to the active form, the rest is excreted as intermediate metabolites (e.g. 6-deoxypenciclovir), which have no significant pharmacological activity.
The elimination half-life of penciclovir is 2-3 hours in patients with normal renal function. The drug is excreted mainly through kidneys (about 60-70% in the form of penciclovir, the rest in the form of metabolites) by tubular filtration and tubule secretion. Complete excretion takes about 24 hours, but with impaired renal function this period may increase.
Famvir is indicated for the treatment of the following conditions:
The drug is effective in reducing the duration of symptoms and preventing recurrences.
The use of Famvir is prohibited in:
Caution is used in severe hepatic insufficiency and immunodeficiency states.
Famvir tablets are taken orally, drinking water (100-150 ml), regardless of meals. Tablets are not chewed and crushed to preserve the stability of the active substance. For maximum efficacy, treatment should be started as soon as possible after the onset of symptoms.
For shingles: 500 mg 3 times daily for 7 days or 750 mg once daily for 7 days. For genital herpes: primary episode - 250 mg 3 times daily for 5 days; relapse - 125 mg 2 times daily for 5 days or 1000 mg once daily. For labial herpes: 1500 mg once or 750 mg twice daily for 1 day.
Dosage is similar to adults, but is used only in strict indications (e.g., shingles).
In renal insufficiency: creatinine clearance 30-59 ml/min - 250 mg 2 times a day (for shingles); 10-29 ml/min - 125 mg once a day. In hepatic insufficiency correction is not required, but monitoring of the condition is necessary.
Possible adverse reactions include:
The side effects are usually mild and pass independently.
Doses above 3000 mg may cause nausea, dizziness, confusion, and rarely acute renal failure.
Stop taking, call a doctor. Gastric lavage (if it has been less than an hour), give activated charcoal. If necessary, hemodialysis.
Famvir has no significant effect on the metabolism of other drugs. Probenecid and cimetidine increase the concentration of penciclovir in blood due to decreased renal clearance.
Alcohol does not affect efficacy but may increase dizziness. Food slows absorption without reducing the therapeutic effect.
Famvir is used in pregnancy only on strict indications; lactation is stopped due to penetration into milk.
The drug may cause dizziness and drowsiness, which requires caution when driving.
In the elderly, the dose is adjusted in case of impaired renal function. In children under 12 years of age the drug is not used due to lack of data.