Waltrex

Valtrex is an effective antiviral drug.

Indications Waltrex

The drug is indicated in the situations described below:

• to eliminate the herpes zoster (which is triggered by the chickenpox virus) - helps to alleviate the pain and shorten its duration, and in addition the percentage of patients with similar pain (among such neuralgia in acute or postherpetic stage);
• elimination of infectious processes on the mucosa along with the skin, which are provoked by conventional herpes of types 1, and 2 (among those acquired for the first time or a recurrent form of genital herpes);
• elimination of herpes with localization on the lips;
• prevention of the formation of lesions on the skin (in case of taking the medicine immediately after the appearance of initial signs of recurrence of a simple form of herpes);
• prevention of the occurrence of recurrences of mucosal diseases together with the skin, which are provoked by ordinary herpes (type 1 and 2), as well as genital type;
• weakening the risk of contracting the genital herpes form of a healthy partner (when taken as a prophylactic and using contraception);
• prevention against the development of a cytomegalovirus form of infection that develops as a result of organ transplantation (reduces the manifestation of the response of a pronounced rejection of a transplanted organ in people with kidney transplants, and also the risk of opportunistic and other types of viral infection that are provoked by chickenpox and herpes simplex).

[1], [2]

Release form

Produced in tablet form - on blisters for 10 pieces. One package contains 1 blister plate.

[3], [4], [5], [6]

Pharmacodynamics

Inside the body, the valaciclovir component is fully and fairly quickly converted to acyclovir substance (by the action of valacyclovirhydrolase). In vitro, the substance exhibits a specific inhibitory activity relative to herpes simplex (type 1 and 2), chickenpox virus, and in addition Epstein-Barr with herpes simplex VI type, as well as cytomegalovirus.

Acyclovir inhibits the binding of DNA of the virus immediately after the phosphorylation reaction with conversion to the active element - acyclovir triphosphate. At the first stage of the phosphorylation process, virus-specific enzymes act. For the above viruses (except for cytomegalovirus with type VI herpes), a similar enzyme becomes viral thymidine kinase, the presence of which is observed inside the cells affected by the virus. Partial selectivity of phosphorylation remains in the cytomegalovirus and is mediated indirectly with the participation of the product produced by the UL 97 kinase gene. Since acyclovir is activated with the help of a specific viral enzyme, this basically explains its selectivity.

At the final stage of phosphorylation of the active component (conversion from mono- to triphosphate components), there are cellular kinases. The newly formed substance competitively suppresses the DNA polymerase within the virus and, therefore, as an analogue of the nucleoside, penetrates into its DNA, promoting complete rupture of this chain and stopping the DNA binding process. As a result, there is a blockage of viral replication.

In people with preserved immunity, chickenpox and herpes simplex viruses, as well as low sensitivity to valaciclovir, are very rare (less than 0.1%). Occasionally, they can occur in patients who have severe disorders in the immune system (for example, with bone marrow transplant, undergoing chemotherapy, and in people infected with the HIV virus).

Stability is due to a lack of viral thymidine kinase, which causes the virus to spread widely around the body. In some cases, a decrease in sensitivity with respect to acyclovir is due to the emergence of viral strains, which disrupts the DNA polymerase or thymidine kinase structure of the virus. The pathogenicity of these types of virus is similar to that of a wild strain of this pathogenic organism.

[7], [8],

Pharmacokinetics

After oral administration of valaciclovir with acyclovir, they acquire the same pharmacokinetic properties.

Once inside the body, valacyclovir is effectively absorbed from the digestive tract - almost entirely and very quickly converted to valine with acyclovir. The catalyzer of this process is the enzyme valacyclovirhydrolase, which is produced by the liver.

With a single use of valacyclovir in the amount of 0.25-2 g, the peak of the acyclovir in the healthy participants taking the drug (normal kidney function) was equal (average) 10-37 μmol (or 2.2-8.3 μg / ml), and the time interval required to reach this level was equal to 1-2 hours.

After using valacyclovir in the amount of 1 + g, the bioavailability of acyclovir was 54% (regardless of food intake).

The peak of the plasma concentration of valacyclovir is only 4% of the acyclovir index. Achievement of the medication of this level occurs on average 30-100 minutes after the use of the dose. After 3 hours, this indicator remains at the same level or decreases.

With plasma protein, acyclovir is synthesized weakly - only by 15%.

In normal kidney function, the half-life of acyclovir is approximately 3 hours. Valaciclovir excretion is carried out with urine, mostly under the guise of acyclovir (80% of the total dosage), as well as its decay product: 9-carboxymethoxymethylguanine. Unchanged excreted less than 1% of drugs.

[9], [10], [11], [12], [13]

Dosing and administration

To eliminate the herpes zoster, adults are required to take the medicine at a rate of 1 g three times a day during the first week.

When treating pathologies triggered by the herpes simplex virus, it is required to drink a medicine in the amount of 500 mg twice a day. If relapses occur, the course of treatment should last 3 or 5 days. With more severe forms of primary diseases, therapy should be started as quickly as possible, increasing its duration to 10 days. When relapsing the disease, it is optimal to start taking the medicine in the prodromal period or immediately after the appearance of the first signs.

As an alternative means to eliminate the herpes form of the herpes, Valtrex is prescribed in the amount of 2 g twice a day. The next one after the first dose is required to be taken after about 12 hours (but it must be taken into account that earlier than 6 hours later) after it. Treatment in this mode should last no more than 1 day, as it does not have additional therapeutic benefits. Begin a similar course should immediately when the first signs - burning, itching and tingling on the lips.

In the form of a preventive remedy for the relapse of infectious diseases provoked by the virus of ordinary herpes, adults with normal immunity should take 500 mg per day once. If relapses are extremely frequent (10+ times a year), it is more appropriate to take a daily dosage of drugs in 2 sets (250 mg each). People with immunodeficiency are prescribed 500 mg twice a day. This course lasts 4-12 months.

In the prevention of infection with the genital herpes form of a healthy partner (adults who have a saved type of immunity with no more than 9 exacerbations per year), the medicine is required to drink once per 500 mg per day for 1+ years. Drinking the drug with regular sexual intercourse is required daily. If the contacts are irregular, you should start to drink drugs for 3 days before possible sexual contact.

For the prevention of cytomegalovirus, children from 12 years and adults should take LS 4 times a day in the amount of 2 g. The medicine should be taken as soon as possible after the transplant. Dosage is reduced depending on the QC indices. The course lasts 90 days, but it can increase in patients who are predisposed to infections.

In the case of kidney failure, the dosage is calculated depending on the indices of the creatinine cleansing factor, as well as the indications.

[15], [16], [17], [18], [19], [20], [21], [22], [23], [24]

Use Waltrex during pregnancy

There are only limited information on the use of Valtrex in pregnant women. It is allowed to prescribe only if the possible benefit for a woman is higher than the risk of fetal side effects.

Contraindications

Contraindication is the patient's intolerance of acyclovir with valaciclovir, and in addition other substances contained in the drug.

Caution is required when prescribing to patients with severe clinical forms of HIV.

Side effects Waltrex

The use of a medicine can trigger the appearance of such side effects:

• organs of the central nervous system: most often headaches. In rare cases dizziness occurs, but also hallucinations, a sense of confusion, a deterioration in mental abilities. There is a single tremor, a feeling of excitement or dysarthria and ataxia, and besides this, convulsions, symptoms of psychotic disorders, as well as the state of coma and encephalopathy develop;

(these effects are reversible and often develop in patients with kidney problems or other health conditions predisposing them, in patients with transplant who take Waltrex as a prophylactic against cytomegalovirus (and in large doses - for a day 8 g), neurological reactions occur more often than with smaller doses)

• organs of the respiratory system: dyspnea appears occasionally;
• organs of the digestive system: occasionally develop diarrhea, vomiting, or discomfort in the abdomen; single - reversible degree of disorders in tests of hepatic function (they are sometimes taken for signs of hepatitis);
• Skin reactions: rashes may appear, as well as symptoms of photosensitization; occasionally itching develops;
• allergies: single - edema Quincke or urticaria;
• organs of the urination system: occasionally a disorder in the functioning of the kidneys; single - acute form of kidney failure;
• others: people with severe immunodeficiency disorders (especially in later stages of AIDS development) who take valaciclovir in large doses (every day for 8 g) for a long time, noted the incidence of kidney failure, thrombocytopenia, and the mechanical form of hemolytic anemia (in individual cases in combination). Similar negative reactions are also detected in patients with similar pathologies that do not take valacyclovir.

[14]

Overdose

There is not enough information about drug overdoses.

In the case of a single oral dose of a large dose of acyclovir (20 g), it is partially absorbed through the gastrointestinal tract without causing toxic effects. Continuing for several days, the use of large doses of acyclovir causes gastrointestinal disturbances (in the form of nausea with vomiting), and also neurologic manifestations (a sense of confusion, and in addition headaches). High doses of the substance, administered intravenously, increase the serum creatinine and, subsequently, the development of kidney failure. Neurological symptoms - the appearance of hallucinations, feelings of excitement or confusion, the development of convulsions, as well as a coma.

The patient needs to stay under constant medical supervision to determine the presence of symptoms of intoxication. The procedure of hemodialysis accelerates the process of excretion from the blood of acyclovir, so it can be considered suitable for patients with overdose of this drug.

[25], [26]

Interactions with other drugs

There was no significant clinical interaction of Valtrex with other drugs.

Excretion of acyclovir in unchanged form is carried out with urine - due to the active process of tubular secretion. With the use of drugs (1 g) in combination with probenecid and cimetidine (they are blockers of tubular secretion), the AUC of acyclovir increases, and its clearance within the kidneys decreases. But you do not need to adjust the dosage of the medicine, because acyclovir has a wide therapeutic index.

Caution should be taken of Valtrex at a higher daily dosage (4 g), combining with acyclovir competitor drugs for the route of elimination, because there is a risk of increasing the performance of any of these drugs (or their decay products) or both of them together inside the blood plasma. In the case of combination with the inactive product of decomposition mycophenolate mofetil (this is an immunosuppressor used in organ transplantation) there is an increase in the AUC of this drug and acyclovir.

It is required to combine the medicine with caution (in doses of 4+ g per day) with drugs that disrupt the work of the kidneys (among them cyclosporin, as well as tacrolimus).

Storage conditions

The drug is contained in standard conditions for medicines, inaccessible to young children. Temperature - no more than 30 ° C.

[27],

Shelf life

Valtrex is suitable for use within 3 years from the date of release of the medicinal product.

[28]