Valavir

Valavir is an antiviral drug used for the complex therapy of cytomegalovirus, Epstein-Barr virus and herpesvirus infections.

Indications Valavira

Indications for use of the drug include:

• As a preventative measure for simple herpes during the period of remission (genital herpes is also taken into account);
• In case of occurrence of signs of herpes zoster (with postherpetic or acute form of neuralgia), as well as infectious infection of the skin or mucous membranes, which occurs as a result of the herpes simplex virus (among these is genital herpes in the primary stage or recurrent form);
• Prevention of cytomegalovirus infection resulting from immunodeficiency of the body (due to bone marrow or other organ transplantation, chemotherapy for cancer, as well as HIV infection).

Release form

The medicine is available in tablet form (No. 10 or No. 42).

Pharmacodynamics

The active component of the drug selectively neutralizes the DNA polymerase of the virus. Once in the patient's body, valacyclovir hydrochloride is metabolized into individual elements: acyclovir, as well as the amino acid valine. The main component affects the DNA polymerase of the virus, reacting with it - thereby slowing down the process of reproduction, as well as the replication of viruses. Prevents the reproduction of Varicella zoster viruses, as well as Hegres simplex groups 1 and 2, EBV, cytomegalovirus and HHV-6.

The selective antiherpetic effect is due to the relationship between the main element and thymidine kinase of the following viruses: Varicella zoster, EBV, and Hegres simplеx. This enzyme is synthesized in cells infected with viruses. As a result of the action of thymidine kinase, acyclovir is phosphorylated, transforming into the active component - acyclovir triphosphate. This element, by competitive substitution, inhibits the assembly of viral DNA.

Pharmacokinetics

Valaciclovir is rapidly absorbed, almost entirely converted into valine, as well as acyclovir. Bioavailability of acyclovir after taking 1 gram of valacyclovir is 54% (and this figure does not depend on food intake). The level of maximum concentration after taking a single dose (250-2500 mg) acyclovir reaches after 1-2 hours and it is equal to 10-37 μmol (within 2.2-8.3 μg / ml). Valaciclovir reaches the maximum saturation in plasma after about 30-100 minutes, and the figure is only 4% of the concentration of acyclovir. And after 3 hours it decreases to a mark below the possible measurable number. Valaciclovir slightly binds to plasma proteins - only 15%.

The half-life of acyclovir is approximately 3 hours, and in patients with end-stage renal failure it is approximately 14 hours. Valaciclovir is excreted in the urine, often as acyclovir (more than 80% of the total dose), and with it its metabolite 9-carboxymethoxymethylguanine.

Dosing and administration

The medicine should be taken orally. It does not depend on food intake.

For herpes zoster: dosage 2 tablets 3 times a day for 1 week (this drug will be most effective if used within 2 days from the onset of symptoms of the disease).

In case of prevention of recurrence of infection due to the herpes simplex virus: patients with a healthy immune status should take 1 tablet 1 time per day.

In case of simple herpes (including genital herpes, as well as its relapses), it is necessary to drink 1 tablet twice a day. The treatment course is 5 days. If severe symptoms are observed and prolonged treatment is required, the course can be extended to 10 days.

Patients with immunodeficiency should take 1 tablet twice a day.

As a preventive measure against cytomegalovirus, the drug is prescribed to children over 12 years of age, as well as adults, in a dosage of 4 tablets four times a day as soon as possible after transplantation.

In case of renal failure, dosage adjustments are required:

Patients with simple (including genital) herpes in case of creatinine clearance rate less than 15 ml/min should drink 1 tablet 1 time/day;

To prevent the recurrence of herpes simplex (in case of creatinine clearance rate less than 15 ml/min or hemodialysis), you need to take 0.5 tablets 1 time/day;

Patients with herpes zoster with a creatinine ratio of 15-30 ml/min should drink 2 tablets twice a day; if the creatinine clearance ratio is less than 15 ml/min, 2 tablets per day are sufficient.

For cytomegalovirus prophylaxis: clearance 50-75 ml/min – 3 tablets four times a day; 25-50 ml/min – 3 tablets three times a day; 10-25 ml/min – 3 tablets twice a day; less than 10 ml/min, and also in case of dialysis – 3 tablets 1 time per day.

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Use Valavira during pregnancy

There is not enough information about the use of the drug during pregnancy, so it should be prescribed (especially in the first trimester) only in cases where the benefit of taking it for the mother is greater than the possible harm to the baby.

Contraindications

Contraindications to taking the drug include: increased individual sensitivity to valacyclovir or acyclovir, or other components of Valavir, as well as children under 12 years of age.

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Side effects Valavira

Side effects of the drug include:

• Gastrointestinal organs: diarrhea, nausea, liver laboratory test results are elevated;
• Organs of the circulatory system: in rare cases thrombocytopenia;
• Allergy: skin rash, itching, urticaria and photosensitivity; rarely, angioedema, dyspnea or anaphylactic shock may occur;
• Excretory system organs: sometimes the functional activity of the kidneys may be impaired;
• Nervous system organs: dizziness or hallucinations appear, in extremely rare cases – a state of coma (if the patient has renal failure);
• Others: In some cases, renal failure or hemolytic anemia, as well as microangiopathy, occurred.

Overdose

In case of overdose of Valavir, the likelihood of side effects may increase.

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Interactions with other drugs

Since acyclovir is excreted in the urine by active renal tubular secretion, other drugs whose metabolic products are excreted in the same way will compete with it for this excretory mechanism. As a result, the blood saturation of acyclovir may increase.

In combination with probenecid, as well as cimetidine, dosage adjustment of Valavir is not necessary, because these drugs slightly reduce the renal clearance rate of acyclovir.

When combined with nephrotoxic drugs, there is a risk of disruption of the functional activity of the central nervous system, as well as the development of renal failure.

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Storage conditions

The drug should be kept in a dry place, protected from sunlight, with a temperature below 25°C.

Shelf life

Valavir is permitted to be used for 2 years from the date of manufacture.