Valavir
Valavir is an antiviral drug used for the complex treatment of cytomegalovirus, Epstein-Bar virus and herpesvirus infection.
Indications of the valavira
Among the indications for the use of the drug:
- As a prophylaxis in the simple form of herpes in the period of remission (genital herpes is also taken into account);
- In the event of signs of herpes zoster (with postherpetic or acute neuralgia), as well as infectious infection of the skin or mucous membranes that occurs as a result of the herpes simplex virus (among them, genital herpes in the primary stage or recurrent form);
- Prevention of cytomegalovirus infection caused by immunodeficiency of the body (due to transplantation to the patient of bone marrow or other organs, chemotherapy for oncological disease, and HIV infection).
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 to separate elements: acyclovir, and also amino acid valine. The main component affects the DNA polymerase of the virus, reacting with it - thereby slowing the reproduction process, as well as the replication of viruses. Prevents the multiplication of viruses Varicella zoster, as well as Negres simlleh 1 and 2 groups, VEB, cytomegalovirus and HHV-6.
Selective antiherpetic effect is due to the relationship of the main element and thymidine kinase of the following viruses: Varicella zoster, VEB, and also Negres simrlx. Synthesis of this enzyme occurs in cells infected with viruses. As a result of exposure to thymidine kinase, acyclovir is phosphorylated by being converted to the active ingredient, acyclovir triphosphate. This element, by competitive substitution, inhibits the assembly of viral DNA.
Pharmacokinetics
Valaciclovir has a rapid absorption, almost entirely converted to valine, as well as acyclovir. The indicators of bioaccessibility of acyclovir after consuming 1 gram of valaciclovir are 54% (moreover, this figure does not depend on the intake of food). Level of maximum concentration after the use of 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). The index of maximum saturation in plasma valacyclovir reaches approximately 30-100 minutes, and the figure is only 4% of the concentration of acyclovir. And after 3:00 it drops to a mark below the possible measurable number. Valaciclovir slightly binds to plasma proteins - only 15%.
The half-life of acyclovir is about 3:00, and in patients with end-stage renal failure it is approximately 14 hours. Valaciclovir excretion occurs together with urine, often as acyclovir (more than 80% of the total dose), and along with it its 9-carboxymethoxymethylguanine metabolite.
Side effects of the valavira
Among the side effects of the drug:
- Gastrointestinal organs: diarrhea, nausea, data on laboratory tests of the liver are increased;
- Organs of the circulatory system: in rare cases, thrombocytopenia;
- Allergies: skin rash, itching, hives and photosensitivity; Occasionally Quincke's edema may appear, shortness of breath or anaphylactic shock;
- The organs of the excretory system: sometimes the functional activity of the kidneys may be impaired;
- The organs of the nervous system: there is dizziness or hallucinations, in extremely rare cases - the state of coma (with renal failure in the patient);
- Other: in some cases, kidney failure or hemolytic anemia, as well as microangiopathy, occurred.
Dosing and administration
You need to take medicine inside. Admission is not dependent on eating.
When herpes zoster form: dosage 2 table. 3 rubles / day. For 1 week. (the most effective this drug will be if it is applied within 2 days from the moment of appearance of signs of the disease).
In the case of prevention of recurrence of infection due to herpes simplex virus: patients who have a healthy immune status should use 1 table. 1 rub. / Day.
In the case of herpes simplex, (including genital herpes, as well as its relapses) it is necessary to drink 1 table. Twice a day. Treatment course is 5 days. If there is severe symptoms and long treatment is required, the course can be prolonged up to 10 days.
Patients with immunodeficiency should use 1 table. Twice a day.
As a prophylaxis of cytomegalovirus, children over 12 years of age, as well as adults, are prescribed medication at a dosage of 4 tablets. Four times a day as soon as possible after transplantation.
When renal insufficiency is required, adjust the dosage:
Patients with simple (including genital) herpes in the case of a creatinine clearance rate of less than 15 ml / min should drink 1 table. 1 rub. / Day;
To prevent the recurrence of herpes simplex (in the case of a creatinine cleansing factor less than 15 ml / min or hemodialysis) 0.5 tablets should be used. 1 pp. / 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 is less than 15 ml / min, 2 tablets per day is sufficient.
When preventing cytomegalovirus: 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 rub. / Day.
Interactions with other drugs
Since acyclovir is excreted together with urine due to active secretion of the renal tubules, other drugs, the metabolic products of which are excreted in the same way, will compete with it for this excretory mechanism. As a result, the saturation in the blood of acyclovir may increase.
In combination with probenecid, as well as cimetidine, dosage adjustment of Valavir is not needed, because these drugs weakly lower the renal clearance factor of acyclovir.
When combined with nephrotoxic drugs, there is a risk of a disorder in the functional activity of the central nervous system, as well as the development of renal failure.