Herpeval

Gerpeval is an antiviral drug. Its active ingredient is valacyclovir (the substance is an L-valine ester of acyclovir, which is an analogue of the nucleoside of purines (guanine)).

Inside the liver, the active component of the drug, with the participation of the valacyclovir hydrolase element, is transformed into two substances – valine and acyclovir. The therapeutic selectivity of acyclovir can mainly be explained by the fact that it is activated by a specific enzyme of the virus. [ 1 ]

Indications Herpeval

It is used in the treatment of the following diseases:

• herpes zoster;
• lesions of the mucous membranes and epidermis associated with the herpes simplex virus (this also includes the genital form of herpes of the primary and recurrent type);
• lip fever.

It is used for preventive therapy of recurrent infections of the epidermis and mucous membranes caused by common herpes (also its genital form). It can be prescribed to reduce the likelihood of transmitting genital herpes to a healthy partner during sexual contact.

Prescribed to prevent CMV infection and the development of pathologies after organ transplantation.

Release form

The medicinal product is released in tablets - 10 pieces in a cell pack; in a box - 1, 2 or 4 such packs.

Pharmacodynamics

Acyclovir specifically slows down the viral action of herpes in vitro (regarding common herpes types 1 and 2, CMV, herpes zoster, EBV and herpes virus type 5). Its active form is acyclovir 3-phosphate, formed during phosphorylation processes with the help of cell kinases (thymidine kinase of the virus). This element competitively slows down the DNA polymerase of the virus and is integrated into its DNA.

Resistance is associated with a deficiency of viral thymidine kinase, which allows the virus to spread excessively within the body. Sometimes, decreased sensitivity to acyclovir is associated with the emergence of viral strains in which the integrity of the DNA polymerase or viral TK structure is impaired. [ 2 ]

In individuals with healthy immunity, a virus with weakened sensitivity to acyclovir is observed sporadically and sometimes develops only in people with severe immune disorders. [ 3 ]

Pharmacokinetics

Valaciclovir has good absorption, almost completely at high speed is transformed into valine with acyclovir. The bioavailability index of acyclovir in case of taking 1 g of valaciclovir is 54% (without reference to food intake). The Cmax values of acyclovir are 10-37 μmol when administering a single portion of 0.25-2 g (after 1-2 hours from the moment of taking the drug). The plasma level of valaciclovir is 4% of the acyclovir values and is recorded after 30-100 minutes (on average); after 3 hours it decreases to a mark below the detectable limit.

Protein synthesis of valacyclovir is extremely low – 15%.

The half-life of acyclovir is approximately 3 hours; in people with terminal renal failure, it is approximately 14 hours. Valaciclovir is excreted in the urine, primarily as acyclovir (over 80% of the dose) and its metabolic unit 9-carboxymethoxymethylguanine.

Dosing and administration

For herpes zoster: take 2 tablets (1 g) of the drug, 3 times a day, during the first week.

Therapy for infections associated with the herpes simplex virus.

For people with healthy immunity – 1 tablet (0.5 g), 2 times a day.

In case of relapses, therapy lasts 3-5 days. In case of primary treatment, which may be more complicated, the course is 10 days. Therapy for relapses of the herpes simplex virus should be started as early as possible - the optimal time to take the drug is during the prodromal stage or immediately after the first signs appear. The drug can prevent the appearance of lesions during a relapse if therapy is started immediately after the development of the first manifestations of the disease.

Alternatively, for the treatment of labial fever, the dosage is 4 tablets (2 g), 2 times per day. The second portion should be taken approximately 12 hours later (at least 6 hours later) from the time of taking the first dose. In the indicated doses, the duration of therapy should be a maximum of 1 day, since it has been found that longer use does not increase the drug's effectiveness. Treatment should be started immediately after the onset of early signs of labial fever (itching, tingling or burning of the lips).

Suppression of recurrence of infections associated with the herpes simplex virus:

• people with healthy immunity are prescribed 1 tablet of the drug (0.5 g), 1 time per day;
• In case of immunodeficiency, it is necessary to take 1 tablet (0.5 g) 2 times a day.

Reducing the likelihood of transmission of genital herpes.

For healthy immunity in individuals with nine or fewer exacerbations of the disease per year, Gerpeval is prescribed in a dosage of 0.5 g once a day.

Prevention of the development of CMV and pathologies after organ transplantation.

The drug is used in a dosage of 4 tablets (2 g), 4 times a day, as soon as possible after the transplant. In case of kidney failure, the doses are reduced. Therapy usually lasts 3 months, but can be prolonged in people with an increased risk.

• Application for children

Prescribed to children aged 12 years and older to prevent the development of CMV or pathologies after transplantation.

Use Herpeval during pregnancy

The use of Gerpeval during pregnancy is permitted only in cases where the possible benefit from it is more likely than the risks of complications for the fetus.

During breastfeeding, the medication is prescribed with caution, only if absolutely necessary. At the same time, valacyclovir can be used in therapy for newborns.

Contraindications

Contraindicated for use in cases of severe intolerance to acyclovir and other components of the drug.

Side effects Herpeval

Main side effects:

• disorders in the nervous system and psyche: dizziness, hallucinations, headache, agitation, confusion, decreased intellectual abilities and ataxia, as well as convulsions, tremors, dysarthria, encephalopathy, psychotic symptoms and comatose state;
• problems with the gastrointestinal tract: diarrhea, nausea, abdominal discomfort and vomiting;
• disorders associated with the hepatobiliary system: temporary increase in liver function tests (sometimes described as hepatitis);
• signs in the lymph and blood system: thrombocytopenia or leukopenia (the latter is mainly observed in people with immunodeficiency);
• immune damage: anaphylaxis occurs occasionally;
• disorders of the respiratory system and sternum organs: dyspnea;
• symptoms affecting the subcutaneous layer and epidermis: rash, which includes signs of photosensitivity, Quincke's edema, urticaria and itching;
• renal and urinary system disorders: acute renal failure, renal dysfunction, lumbar pain and hematuria (often associated with other renal dysfunctions). Kidney pain may be associated with renal failure;
• Others: there are reports of renal failure, hemolytic anemia of the microangiopathic type and thrombocytopenia (sometimes in combination) in people with severe immunodeficiency, especially in people with late-stage HIV, who have used valacyclovir in large doses (8 g per day) for a long time. Similar symptoms have also been noted in people with similar pathologies who have not used valacyclovir.

Overdose

Signs of poisoning: vomiting, acute renal failure, nausea, neurological manifestations including hallucinations, confusion, loss of consciousness, agitation and coma.

Symptomatic measures and hemodialysis are carried out.

Interactions with other drugs

Valaciclovir is excreted in the urine by active tubular secretion, and other drugs competing for this route of excretion may increase plasma levels of one or both drugs and their metabolites.

Administration in combination with mycophenolate mofetil (an immunosuppressant used in organ transplantation) increases plasma levels of acyclovir and the inactive metabolic component of mycophenolate mofetil.

It is necessary to carefully combine large doses of Gerpeval (4+ g) with other drugs that change renal function (for example, tacrolimus or cyclosporine).

Storage conditions

Gerpeval should be kept out of the reach of small children. Temperature readings are no more than 30°C.

Shelf life

Herpeval can be used for a period of 24 months from the date of production of the therapeutic substance.

Analogues

Analogues of the drug are Vairowa, Vacirex, Valcicon with Valavir, Valmik and Valmax with Valacitek. In addition, the list includes Valogard, Valtrovir with Herpacivir, Valcik and Virdel.