Zovirax

Zovirax has antiviral properties.

Indications Zovirax

The tablets are used for the following disorders:

• elimination of infections caused by the activity of the chickenpox virus and shingles;
• treatment of infections occurring in the mucous membranes and skin, HSV of any type (this includes genital herpes, which has a primary or recurrent form);
• prevention of recurrence of HSV infections of any type in people with healthy immunity or with immunodeficiency;
• treatment of people with severe immunodeficiency (often HIV infection with CD4+ below 200 cells/μl and early symptoms of HIV, as well as clinical manifestations of AIDS ) or after bone marrow transplantation.

The use of the drug in ointment form is carried out for keratitis caused by HSV of any type.

The cream is prescribed to eliminate any type of HSV infection that occurs on the mucous membranes and skin surface (this includes herpes in the lip area).

Using injection fluid:

• treatment of HSV infections of any type;
• prevention of the development of infections of any type of HSV on the mucous membranes or surface of the skin in people with immunodeficiency;
• elimination of infections caused by the varicella-zoster virus;
• treatment of HSV infections of any form in newborn infants;
• prevention of CMV development after bone marrow transplantation procedure.

Release form

The drug is released in several forms:

• tablets, 5 pieces inside a blister pack, 5 packs inside a pack;
• 5% cream applied externally - in plastic bottles with a capacity of 2 g, equipped with a dispenser. Inside the box there is 1 such bottle. Also produced in tubes of 2, 5 or 10 g, 1 tube inside the package;
• ointment in a 4.5 g tube with a plastic nozzle. Inside the pack there is 1 such tube;
• injection lyophilisate - in glass vials with a capacity of 0.25 g. Inside the blister pack there are 5 such vials. The box contains 1 such package.

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Pharmacodynamics

An antiviral agent, a synthetic analogue of a purine nucleoside, which has the ability to slow down the viral replication of HSV of any type, CMV, Varicella zoster, and also EBV. The substance acyclovir has a powerful antiviral effect on the herpes virus type 1.

The drug's activity against viruses is highly selective. Thymidine kinase of the cells affected by the viruses described above converts the molecules of the active element of the drug into monophosphate, and then sequentially into 2-phosphate and 3-phosphate (under the influence of cellular enzymes). Due to the inclusion of 3-phosphate of the active element in the chain of viral DNA with subsequent rupture of this chain, the copying of pathogenic DNA is blocked.

In individuals with severe immunodeficiency, prolonged or repeated courses of therapy with acyclovir may cause the development of drug-resistant strains. Also, low values of viral thymidine kinase were observed in many strains with low sensitivity to Zovirax.

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Pharmacokinetics

Pharmacokinetic properties of injections and tablets.

After oral administration, the active element is only partially absorbed from the gastrointestinal tract. The level of the substance in the cerebrospinal fluid is approximately half of its values in the plasma. Only a small part of the drug is synthesized with blood protein (10-33%).

The main metabolic product is the substance 9-carboxymethoxymethylguanine. The half-life is 2.7-3.3 hours. The main part of the drug is excreted as an unchanged element through the kidneys. This occurs through the processes of glomerular filtration and tubular secretion.

In people with chronic renal failure, the half-life of the drug is approximately 19.5 hours. In older people, the drug clearance rate decreases with age, but changes in the half-life are almost imperceptible.

Pharmacokinetic characteristics of the ointment.

After using the ointment, the active element is quickly absorbed through the corneal epithelium and tissues located around the eyes, resulting in the formation of a therapeutic concentration in the intraocular fluid required to suppress the activity of the virus.

With this method of use, acyclovir is found in the urine in extremely low concentrations that have no medicinal value.

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Dosing and administration

Scheme of using the medicine tablets.

The tablets should be taken orally, with food, washed down with plain water (0.2 l).

To eliminate infections associated with HSV, it is necessary to take 0.2 g of the drug at intervals of 4 hours, 5 times a day. The treatment course usually lasts 5 days, but in the treatment of severe forms of the disease it can be extended. If the patient has a pronounced degree of immunodeficiency or a violation of the intestinal absorption of the drug, the size of the portion can be increased to 0.4 g while maintaining the above frequency of use. It is recommended to begin therapy as soon as possible after the onset of infection. In case of relapses of the disease, the drug is taken immediately after the first signs appear.

To prevent the development of relapses of HSV-associated infections in people with a healthy immune system, the drug should be taken four times a day, 0.2 g, with equal time intervals between doses. There is also an option with a more convenient regimen of use - 0.4 g twice a day. Sometimes, smaller doses of the drug - 0.2 g 2-3 times a day - demonstrate higher efficiency. In some patients, infection can only be prevented after taking the total daily dose of 0.8 g.

Treatment must be stopped periodically (at intervals of 0.5-1 year) to determine whether there are any changes in the course of the disease.

When preventing the development of relapses of HSV-related infections in people with immunodeficiency, it is necessary to take 0.2 g of the drug four times a day. People with a pronounced degree of immunodeficiency or impaired intestinal absorption are allowed to increase the portion size to 0.4 g, which is taken five times a day. The period of preventive therapy is selected taking into account the duration of the infectious period.

To treat herpes zoster and chickenpox, take 0.8 g of the medicine five times a day (excluding the period of night sleep). This therapy lasts 7 days. The medicine should be prescribed as soon as possible after the infection develops to increase the effectiveness of the treatment.

In the treatment of patients with severe immunodeficiency, 0.8 g of Zovirax is prescribed four times a day (with equal time intervals between doses). People who have undergone bone marrow transplantation often require a 1-month course with parenteral administration of the drug before oral administration of the drug. Treatment in people who have had a bone marrow transplant lasts no more than 0.5 years. In people with an advanced clinical picture of HIV, the duration of therapy was 12 months.

For individuals with severe renal impairment, Zovirax dosages should be reduced to 0.2 g, taken twice daily.

When treating chickenpox or shingles, and in addition to this therapy for people with severe immunodeficiency, the standard portion sizes are:

• in severe stages of renal failure – 0.8 g twice a day;
• for moderate renal failure – 0.8 g three times a day.

Mechanism of application of eye ointment.

A 10 mm long strip of ointment should be placed in the conjunctival sac area. The procedure is performed a maximum of 5 times a day. After the symptoms of the disease have been eliminated, therapy should be continued for at least another 3 days.

Scheme of using the cream.

The cream should be applied with a cotton swab or clean hands to prevent reinfection of the affected areas.

A small amount of the preparation should be applied to the affected areas, as well as to the skin/mucous membranes near them. The procedure is performed up to 5 times a day.

The duration of therapy is usually 4 days. If the wound does not heal, the treatment can be extended to 10 days. If there is no result after 10 days of therapy, you should consult your doctor.

Mode of use of injection lyophilisate.

The prepared solution should be administered intravenously. Obese people are given the same doses of the drug as people with a healthy weight.

When eliminating infections caused by the activity of HSV, as well as the herpes zoster virus, the medication is administered intravenously in a dose of 5 mg/kg, three times per day.

For the treatment of infections associated with herpes encephalitis or herpes zoster in people with immunodeficiency, an intravenous injection of 10 mg/kg three times a day is required.

To prevent the development of CMV after bone marrow transplantation, the drug is administered intravenously in a dose of 0.5 mg/m2 ^, three times a day. Treatment begins on the 5th day before the transplant procedure and then continues until the 30th day after it.

It is necessary to carefully select dosages for elderly people with reduced CC values - the introduction of reduced portions is required.

People with renal failure should be given Zovirax IV injections with caution. The dose size should be adjusted according to the severity of the disease.

Infusion therapy usually lasts 5 days, although the course may vary depending on the patient's response to treatment and his condition. The length of the prophylactic period is selected depending on the duration of the infectious period.

Preparation of medicinal liquid and methods of administration.

The drug is administered intravenously at a slow speed. The procedure lasts more than 60 minutes.

To prepare a solution with an active ingredient concentration of 25 mg/ml, add 10 ml of regular water or saline solution into the ampoule with the lyophilisate, then shake it gently until the contents are completely dissolved.

Another method of preparing the infusion can be used: the ready-made solution is diluted to obtain a concentration of 5 mg/ml (in this case, the ready-made infusion fluid should be added to one of the solutions, and then shaken so that these solutions are completely mixed). Adults should be prescribed infusions in 0.1 l bags, despite the indicators of diluted acyclovir, which are less than 0.5%.

For intravenous injections, the drug can be combined with the following solutions (the drug will remain stable for 12 hours at temperatures within 15-24°C):

• 0.18% NaCl solution and 4% glucose solution;
• 0.45% NaCl solution and 2.5% glucose solution;
• 0.45% or 0.9% NaCl solution;
• Hartmann's solution.

Application for children

Using tablets.

For the elimination and prevention of diseases caused by HSV in children who suffer from immunodeficiency:

• infants under 2 years of age are prescribed half the adult portion;
• Children over 2 years of age are required to take the medicine in the doses recommended for adults.

When treating chickenpox, the following dosages are prescribed:

• infants under 2 years of age are required to take 0.2 g of the drug four times a day;
• children aged 2-6 years should take 0.4 g of the drug four times a day;
• Children over 6 years of age should take 0.8 g of the medicine four times a day.

A more precise portion size can be selected based on the child's weight - 20 mg/kg four times a day. The duration of treatment is usually 5 days.

Use of injection lyophilisate.

The dose sizes for intravenous injections for children aged 3 months to 12 years are determined taking into account the size of the body surface area.

During the treatment of pathologies caused by the activity of HSV (except for encephalitis of herpetic origin), and in addition to this herpes zoster virus, the sizes of intravenous infusions are selected based on the calculation of 0.25 g/m2 ^three times per day.

When eliminating infections caused by viral activity (herpes zoster, as well as herpes encephalitis), for children with immunodeficiency, dosages are selected according to the scheme of 0.5 g/m2 ^three times a day.

For newborns, portions are selected taking into account their weight.

To eliminate HSV-associated infections in newborns, a suitable dosage should be selected according to the scheme of 10 mg/kg, with three times a day. Usually, such treatment lasts 10 days.

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Use Zovirax during pregnancy

Zovirax should be prescribed to pregnant or lactating women with extreme caution, only if there are medical indications and after careful assessment of the likelihood of benefit from use and the risk to the woman and child/fetus.

Tests found no increase in birth defects in children whose mothers used the drug during pregnancy compared to children whose mothers did not use it.

Contraindications

The main contraindication is intolerance to valacyclovir or acyclovir and other components of the drug.

Intravenous injections are prohibited in the following cases:

• dehydration;
• renal failure;
• neurological disorders;
• negative reactions to intravenous injections of cytotoxic drugs (also their presence in the past).

Taking tablets is prohibited in case of dehydration and kidney failure.

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Side effects Zovirax

When using powder or tablets, the following side effects may occur:

• digestive disorders: nausea, diarrhea, vomiting, and abdominal pain (when taken orally);
• disorders of the hematopoietic system: anemia, thrombocytopenia or leukopenia;
• manifestations of hypersensitivity: fever, angioedema, dyspnea, rash, urticaria, anaphylaxis, itching, photosensitivity and severe forms of inflammation at the site of parenteral administration;
• renal impairment: increased urea and creatinine levels in the blood. To avoid such symptoms, instead of rapid intravenous injection, use a slower rate (the procedure should last 60 minutes). Renal failure caused by intravenous injections of drugs is often eliminated by reducing the dose of the drug or performing a rehydration procedure;
• liver disorders: transient increase in liver enzymes and bilirubin, as well as the development of hepatitis or jaundice (rarely, after parenteral administration);
• lesions affecting the function of the nervous system: a feeling of drowsiness, confusion, and nervous excitement. In addition, the development of seizures, psychosis, hallucinations, tremors, coma, and headaches (if taken orally);
• other disorders: alopecia and a state of severe fatigue.

Disorders caused by using eye ointment:

• immune disorders: manifestations of intolerance, which can lead to Quincke's edema;
• visual disturbances: conjunctivitis, mild transient burning, blepharitis, and also punctate keratopathy (disappears without complications; there is no need to stop therapy for this).

Negative symptoms that occur after using the cream:

• local symptoms: transient itching, burning sensation, redness, peeling, and tingling at the treatment site;
• manifestations of allergy: angioedema, as well as dermatitis.

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Overdose

Pill poisoning.

In case of a single accidental oral administration of doses of the drug up to 20 g, no side effects are observed.

Symptoms of overdose include vomiting, diarrhea, headaches, nausea, dyspnea, and a feeling of confusion. In addition, seizures, renal dysfunction, coma, and lethargy may also occur.

The patient should be closely monitored to detect symptoms of poisoning in a timely manner. Hemodialysis may be used.

Solution intoxication.

Symptoms of poisoning: development of kidney failure, convulsions, coma, feelings of excitement or confusion, and hallucinations. In addition, an increase in creatinine and urea nitrogen in the blood is noted.

To eliminate the disorders, a hemodialysis procedure is required, because it significantly increases the excretion of acyclovir from the body. Due to this, this procedure is considered the optimal method of treatment in case of intoxication with Zovirax solution.

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Interactions with other drugs

Unchanged acyclovir enters the urine via tubular secretion, so all drugs that have a similar excretion pathway are capable of increasing acyclovir levels in the blood.

It is necessary to combine intravenous injections of Zovirax with drugs that impair renal function (such as tacrolimus, cyclosporine, etc.) with caution.

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Storage conditions

Zovirax should be stored in a dry place, out of reach of children. Temperature conditions are standard for medicines.

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Shelf life

Zovirax can be used for 5 years from the date of manufacture of the therapeutic agent.

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Analogues

The following drugs are analogs of the drug: Acyclovir, Acyclovir-Akri, Acyclovir Belupo, as well as Acyclovir-Akrikhin and Acyclovir Sandoz. In addition, the list includes Atsigerpin, Acyclostad, Gerperax with Vivorax and Medovir, as well as Acivir, Virolex, Zovirax Duo and Provirsan with Gerpetad.

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Reviews

Zovirax receives mostly positive reviews, which note the high medicinal effectiveness of the drug. It is often used to treat herpes. In reviews, there are almost no reports of a lack of results after using the drug, as well as the development of side effects. The only downside, according to patients, is the high cost of the drug.