Zovirax, pills 200mg, 25pcs

Composition

Active ingredient:  acyclovir 200.0 mg;

Other components:

lactose monohydrate,

microcrystalline cellulose,

sodium carboxymethyl starch,

povidone K 30,

magnesium stearate.

Pharmacological action

Pharmacological group: antiviral agent. ATX code: [J05AB01]Pharmacological PROPERTIESPHARMACODYNAMICMECHANISM ACYCLOVIR is a synthetic purine nucleoside analog that has the ability to inhibit in vitro and in vivo replication of human herpes viruses, including herpes simplex virus (HSV) types 1 and 2, varicella zoster virus (VZV), Epstein – Barr virus (EBV) and cytomegalovirus (CMV). In cell culture, acyclovir has the most pronounced antiviral activity against HSV-1, followed by HSV-2, VZV, EBV and CMV in descending order of activity. The effect of acyclovir on herpes viruses (HSV-1, HSV-2, VZV, EBV, CMV) is highly selective. Acyclovir is not a substrate for the enzyme thymidine kinase in uninfected cells, so acyclovir is not toxic to mammalian cells. Thymidine kinase in cells infected with HSV, VZV, EBV, and CMV viruses converts acyclovir to acyclovir monophosphate, a nucleoside analog that is then sequentially converted to diphosphate and triphosphate by cellular enzymes. The inclusion of acyclovir triphosphate in the viral DNA chain and subsequent chain breakage block further replication of viral DNA. In patients with severe immunodeficiency, prolonged or repeated courses of acyclovir therapy may lead to the formation of resistant strains, and therefore further treatment with acyclovir may not be effective. Most of the isolated strains with reduced sensitivity to acyclovir showed relatively low levels of viral thymidine kinase and impaired structure of viral thymidine kinase or DNA polymerases. Exposure of acyclovir to HSV strains in vitro can also lead to the formation of less sensitive strains. There is no correlation between the sensitivity of HSV strains to acyclovir in vitro and the clinical efficacy of the drug. Pharmacokinetics Acyclovir is only partially absorbed from the intestine. After taking 200 mg of acyclovir every 4 hours, the mean maximum steady-state plasma concentration (Cssmax) was 3.1 µmol (0.7 µg/ml), and the mean steady-state minimum plasma concentration (Cssmin) was 1.8 µmol (0.4 µg/ml). When taking 400 mg and 800 mg acyclovir every 4 hours, Cssmax was 5.3 mmol (1.2 mcg / ml) and 8 mmol (1.8 mcg/ml), respectively, and Cssmin was 2.7 mmol (0.6 mcg/ml) and 4 mmol (0.9 mcg/ml), respectively. The elimination half-life of acyclovir is 2.5-3.3 hours. Most of the drug is excreted unchanged by the kidneys. Renal clearance of acyclovir significantly exceeds creatinine clearance, which indicates that acyclovir is eliminated not only by glomerular filtration, but also by tubular secretion. The main metabolite of acyclovir is 9-carboxymethoxy-methylguanine, which accounts for about 10-15% of the administered dose in the urine. When acyclovir was administered 1 h after taking 1 g of probenecid, the half-life of acyclovir and the area under the plasma concentration – time curve increased by 18 and 40%, respectively. In the elderly, acyclovir clearance decreases with age in parallel with a decrease in creatinine clearance, however, the half – life of acyclovir changes slightly. In patients with chronic renal failure, the average elimination half-life of acyclovir was 19.5 hours. During hemodialysis, the average half-life of acyclovir was 5.7 hours, and the concentration of acyclovir in plasma decreased by approximately 60%. The concentration of acyclovir in the cerebrospinal fluid is approximately 50% of its plasma concentration. Acyclovir is slightly bound to plasma proteins (9-33%), so drug interactions through the protein binding mechanism are unlikely. When acyclovir and zidovudine were co-administered to HIV-infected patients, the pharmacokinetic characteristics of both drugs remained virtually unchanged.

Indications

• Treatment of infections of the skin and mucous membranes caused by the herpes simplex virus, including primary and recurrent genital herpes;
• Prevention of recurrent infections caused by the herpes simplex virus in patients with normal immune status;
• Prevention of infections caused by the herpes simplex virus in patients with immunodeficiency;
• Treatment of chickenpox and herpes zoster;
• Treatment of patients with severe immunodeficiency, mainly with advanced stages of HIV infection (CD4+ cell count less than 200 / mm in patients with AIDS or severe manifestations of the AIDS-associated complex) and patients who have undergone bone marrow transplantation. Studies have shown that combined therapy with Zovirax and antiretroviral agents (mainly oral zidovudine) significantly reduces mortality in patients with advanced stages of AIDS and patients who have undergone bone marrow transplantation.

Use during pregnancy and lactation

Pregnancy Analysis of acyclovir treatment in women during pregnancy showed no increase. the number of birth defects in their children compared to the general population. However, caution should be exercised when prescribing Zovirax to women during pregnancy and evaluating the intended benefit to the mother and the possible risk to the fetus. Lactation After taking Zovirax orally at a dose of 200 mg 5 times a day, acyclovir was detected in breast milk at a concentration ranging from 60 to 410% of the plasma concentration. At such concentrations in breast milk, children who are breastfed can receive acyclovir at a dose of up to 0.3 mg / kg / day. Given this, caution should be exercised when prescribing Zovirax to nursing women.

Contraindications

Zovirax is contraindicated in cases of hypersensitivity to acyclovir or valacyclovir.

Zovirax should be used with caution in patients with dehydration and renal failure.

Zovirax in tablet dosage form is not used in children under the age of 3 years.

Side effects

From the digestive system: nausea, vomiting, diarrhea, abdominal pain; rarely-reversible increase in the level of bilirubin and activity of liver enzymes. From the hematopoietic system: very rarely – anemia, leukopenia, thrombocytopenia. From the urinary system: rarely-increased levels of urea and creatinine in the blood; very rarely-acute renal failure. From the central nervous system: headache; rarely-reversible neurological disorders, such as dizziness, confusion, hallucinations, drowsiness, convulsions, coma. Usually, these side effects were observed in patients with renal insufficiency who took the drug at doses higher than recommended. Allergic reactions: rash, photosensitivity, urticaria, pruritus; rarely-shortness of breath, angioedema, anaphylaxis. Other: rapid fatigue; rarely-rapid diffuse hair loss. Since this type of alopecia is observed in various diseases and during therapy with many medications, its relationship with acyclovir has not been established. In patients receiving antiretroviral drugs, additional Zovirax use did not cause a significant increase in toxic effects.

Interaction

Acyclovir is excreted unchanged in the urine by active tubular secretion. All drugs with a similar elimination route may increase the plasma concentration of acyclovir. BCC and cimetidine increase the AUC of acyclovir and decrease its renal clearance (no dose adjustment is required due to the wide range of therapeutic doses of acyclovir).

In patients receiving intravenous Zovirax, caution should be exercised when prescribing concomitant medications that compete for the elimination route due to the potential increase in plasma levels of one, both drugs or their metabolites. The combined use of acyclovir and mycophenolate mofetil leads to an increase in the AUC for acyclovir and the inactive metabolite mycophenolate mofetil. With caution, intravenous use of Zovirax should be combined (monitoring of renal function is necessary) with drugs that violate renal function (for example, cyclosporine, tacrolimus).

How to take, course of use and dosage

Zovirax tablets can be taken with a meal, since food intake does not significantly interfere with its absorption. Tablets should be washed down with a full glass of water.

Adults

Treatment of infections caused by the herpes simplex virus For the treatment of infections caused by the herpes simplex virus, the recommended dose of Zovirax is 200 mg 5 times a day every 4 hours, with the exception of nighttime sleep. Usually, the course of treatment is 5 days, but can be extended for severe primary infections.

In the case of severe immunodeficiency (for example, after bone marrow transplantation) or with impaired intestinal absorption, the dose of Zovirax for oral use can be increased to 400 mg 5 times a day.

Treatment should be started as early as possible after the infection occurs; in case of relapses, the drug is recommended to be prescribed already in the prodromal period or when the first elements of the rash appear.

Prevention of relapses of infections caused by herpes simplex virus To prevent relapses of infections caused by herpes simplex virus in patients with normal immune status, the recommended dose of Zovirax is 200 mg 4 times a day (every 6 hours).

For many patients, a more convenient treatment regimen of 400 mg 2 times a day (every 12 hours) is suitable.

In some cases, lower doses of Zovirax 200 mg 3 times a day (every 8 hours) or 2 times a day (every 12 hours) are effective. In some patients, interruption of infection may occur with a total daily dose of 800 mg.

Treatment with Zovirax should be periodically interrupted for 6-12 months to detect possible changes in the course of the disease.

Prevention of herpes simplex virus infections in immunodeficient patients:For the prevention of infections caused by the herpes simplex virus, in patients with immunodeficiency, the recommended dose of Zovirax is 200 mg 4 times a day (every 6 hours).

In the case of severe immunodeficiency (for example, after bone marrow transplantation) or with impaired intestinal absorption, the dose of Zovirax for oral use can be increased to 400 mg 5 times a day. The duration of the preventive course of therapy is determined by the duration of the period when there is a risk of infection.

Treatment of chickenpox and herpes zoster:For the treatment of chickenpox and herpes zoster, the recommended dose of Zovirax is 800 mg 5 times a day; the drug is taken every 4 hours, with the exception of the nighttime sleep period. The course of treatment is 7 days. The drug should be prescribed as early as possible after the onset of infection, since in this case the treatment is more effective.

Treatment of patients with severe immunodeficiency:For the treatment of patients with severe immunodeficiency, the recommended dose of Zovirax is 800 mg 4 times a day (every 6 hours).

Patients who have undergone a bone marrow transplant are usually recommended to receive intravenous therapy with Zovirax for 1 month before being prescribed Zovirax for oral use.

In clinical trials, the maximum duration of treatment for recipients of bone marrow transplants was 6 months (from 1 to 7 months after transplantation). In patients with a developed clinical picture of HIV infection, the course of treatment with Zovirax was 12 months, but there is reason to believe that longer courses of therapy may be effective in such patients.

Children aged 3 years and older

Treatment and prevention of herpes simplex virus infections in children with immunodeficiency and normal immune status: from 3 years and older – the same doses as for adults;

Treatment of chickenpox

• older than 6 years-800 mg 4 times a day;
• from 3 to 6 years-400 mg 4 times a day;

More precisely, the dose can be determined at the rate of 20 mg/kg of body weight (but not more than 800 mg) 4 times a day. The course of treatment is 5 days.

There are no data on the prevention of recurrent infections caused by the herpes simplex virus and on the treatment of herpes zoster in children with normal immune parameters.

Treatment of paediatric patients with severe immunodeficiency According to very limited information, the same doses of Zovirax can be used for the treatment of children over 3 years of age with severe immunodeficiency as for the treatment of adults with immunodeficiency (i. e. 800 mg 4 times a day every 6 hours).

Elderly patients In the elderly, acyclovir clearance decreases in the body in parallel with a decrease in creatinine clearance.

Elderly patients should receive sufficient fluids while taking high doses of Zovirax orally, and if they have renal insufficiency, they should decide whether to reduce the dose of Zovirax.

Patients with renal insufficiency Caution should be exercised when prescribing Zovirax to patients with renal insufficiency.

In patients with renal insufficiency, oral use of acyclovir at the recommended doses for the treatment and prevention of infections caused by the herpes simplex virus does not lead to accumulation of the drug to concentrations exceeding the established safe levels. However, in patients with severe renal insufficiency (creatinine clearance less than 10 ml / min), the dose of Zovirax is recommended to be reduced to 200 mg 2 times a day (every 12 hours).

In the treatment of varicella, herpes zoster, and in the treatment of patients with severe immunodeficiency recommended dose of Zovirax are:

• severe renal insufficiency (creatinine clearance less than 10 ml/min) 800 mg 2 times a day every 12 hours;
• moderate renal insufficiency (CRCL 10-25 ml/min) 800 mg 3 times per day every 8 hours.

Overdose

Symptoms Acyclovir is only partially absorbed in the gastrointestinal tract. No toxic effects have been reported with random single oral doses of acyclovir up to 20 g. Repeated oral doses exceeding the recommended dose range for several days were associated with gastrointestinal disorders (nausea, vomiting) and neurological disorders (headache and confusion).

Sometimes there may be shortness of breath, diarrhea, impaired kidney function, agitation, confusion, hallucinations, seizures, coma.

Treatment Patients should be closely monitored for possible symptoms of intoxication. Acyclovir is eliminated from the body by hemodialysis, so hemodialysis can be used if symptoms of intoxication develop.

Special instructions

Hydration status: Patients taking high oral doses of Zovirax should receive sufficient fluids. Elderly patients and patients with renal insufficiency: Patients in this group are at an increased risk of developing side effects from the nervous system (usually such reactions are reversible in response to drug withdrawal), respectively, should be under close medical supervision. Transmission of infection: Patients should be informed about the possibility of transmission of genital herpes virus during rashes, as well as about cases of asymptomatic virus transmission. IMPACT ON THE ABILITY TO DRIVE A CAR WITHOUT data.

Form of production

Tablets of 200 mg. 5 tablets in a blister of PVC/GSHDH/A 1; 5 blisters in a cardboard pack together with the instructions for use.

Storage conditions

Store in a dry place, at temperatures below 25°C. Keep out of reach of children.

Shelf life

5 years

Active ingredient

Acyclovir

Conditions of release from pharmacies

By prescription

Dosage form

Tablets

Indications

HIV Infection, Genital Herpes, Herpes Zoster, Chickenpox