Pharmacodynamics and pharmacokinetics
The active ingredient of the drug inhibits the activity of DNA polymerase herpes viruses , prevents the synthesis of viral DNA and inhibits replication processes.
After entering the body, valacyclovir is transformed into acyclovir and L-valine , then phosphorylation and acyclovir is converted into acyclovir triphosphate . The resulting compound is capable of inhibiting the DNA polymerase of a harmful agent (virus) through a competitive mechanism.
Phosphorylation usually occurs in two stages. In the first, the reaction is catalyzed by the enzyme thymidine kinase .
The drug exhibits particular activity against Herpes simplex; it is less sensitive to Varicella zoster. The substance is excreted by the kidneys or feces; the half-life is approximately three hours.
Valacyclovir - composition and action
The tablets contain valacyclovir hydrochloride (valacyclovirum) and excipients - cellulose, starch, castor oil, chemical compounds - titanium dioxide, polysorbate, polyethylene glycol. Auxiliary components provide the drug with a tablet form, uniform consistency and color.
In the human liver, valacyclovir is converted into acyclovir (a substance with a specific antiviral effect against herpes types 1 - 6). After transformation, it inhibits and stops the reproduction of viruses. The action of acyclovir is specific; it does not affect healthy cells, but destroys only those that are infected.
Note Viruses do not have their own cells. They are integrated into the DNA of the host (human) cell and use its structure for their own reproduction. An infected human cell ceases to perform its functions and becomes a factory for the production of foreign cells. Therefore, herpes is called an intracellular parasite. To reproduce, it needs a “master” whose vital juices it will use.
Due to their introduction into living cells, viruses are difficult to fight; it is necessary to destroy the cells of your own body. The specific effect of acyclovir is that it destroys only infected cells. It is integrated into the DNA of the cell (in fact, it is already the DNA of the virus
) and stops the synthesis of new viruses. As a result, new rashes stop appearing, healing of existing wounds accelerates, and crusts dry out.
Side effects
The drug has been well researched. As a result of laboratory studies and observations of patients with herpes zoster and herpes virus (including those with concomitant immunodeficiency ) taking valacyclovir , almost all possible adverse reactions were identified.
Possible:
- nausea, pain in the epigastric region, vomiting, anorexia and diarrhea , increased activity of liver enzymes, hepatitis ;
- impaired renal function, photosensitivity , shortness of breath, thrombocytopenia ;
- headaches, dizziness , hallucinations , depression , agitation , ataxia , psychosis , dysarthria , disturbances of consciousness and coma ;
- rash , itching , anaphylaxis , urticaria , Quincke's edema ;
- neutropenia , aplastic anemia , vasculitis , thrombocytopenia ;
- nasopharyngitis , facial swelling , tachycardia , increased blood pressure , increased fatigue;
- rhinorrhea , fever and dehydration .
Indications for use
For patients over 12 years of age, the use of Valaciclovir is indicated:
- treatment and prevention (including in adults with immunodeficiency) of infectious diseases of the mucous membranes and skin caused by the herpes simplex virus [including labial herpes (Herpes labialis) and newly diagnosed or recurrent genital herpes (Herpes genitalis)];
- prevention of infectious pathologies after solid organ transplantation;
- prevention of cytomegalovirus infections.
In addition, only adults are prescribed tablets for the treatment of herpes zoster, including ophthalmic herpes zoster.
Instructions for use of Valaciclovir (Method and dosage)
The drug is taken orally, regardless of food.
Valacyclovir tablets, instructions for use
For herpes zoster, a single dosage is 1000 mg (2 tablets), 3 times a day. The course of treatment is 7 days. The sooner the drug is started after the first symptoms of the disease appear, the more effective the treatment will be.
For herpes (including prophylactic use), the daily dosage is 1000 mg. It is recommended to divide into 2 doses, morning and evening, one tablet each. The duration of treatment is from 5 to 10 days (severe course of the disease).
If the patient has impaired renal function, the dose should be adjusted.
Reviews about the drug
According to reviews of people who treated herpetic rashes with valacyclovir, it is an average drug between the cheap acyclovir and the more expensive famvir. Valacyclovir is slightly more expensive than acyclovir. But at the same time, it treats not only simple rashes, but also herpes zoster more effectively and better.
Review statistics boil down to the following:
- The drug is available in pharmacies (it can be purchased at most pharmacies);
- Side effects are possible and not uncommon;
- Average efficiency;
- Adequate price-quality ratio;
- 60% of those treated with this drug would recommend the drug to friends.
- Svetlana, Veliky Novgorod: Valtrex was prescribed for the treatment of genital herpes immediately in a large dose (three times a day, 1 g). The next day there was severe lower back pain and diarrhea. My kidneys are healthy. You probably can’t start with large doses of the drug right away, you need to be sure that your body will not react to it the way mine did.
- Andrey, Rostov-on-Don: Valtrex and Famvir are less toxic to the liver than acyclovir. They are expensive, but my liver is more expensive to me. Treatment for relapses of herpes must be done periodically. Therefore, it is better to overpay and be sure that there will be no side complications or anything else.
- Orina, Vanadzor: For me, Valavir is salvation. Prescribed by an infectious disease specialist, I have been suffering from herpetic rash for many years with varying success - it goes away and then appears again. In general, it helped me, although it was expensive, I would like it to be cheaper.
- Sergey, Khabarovsk: Valavir was prescribed by a doctor. Herpes appeared in the corner of the lips. I don’t suffer from frequent herpes, but it does happen. After three days the bubbles disappeared almost completely (a pink spot remained). This is good - it usually takes longer. There were no allergies.
Interaction
There were no clinically significant cases of interaction between tablets and other drugs.
However, the active substance is excreted from the body through the kidneys by tubular secretion . Any medications that are prescribed simultaneously with Valacyclovir will interfere with its normal elimination from the body. This primarily applies to Cimetidine and other drugs that block the mechanism of tubular secretion.
When combined with Mycophenolate , the concentration of acyclovir in the blood plasma increases.
When the drug is combined with Cyclosporine , Tacrolimus and drugs that interfere with the normal functioning of the kidneys, the load on these organs increases.
Use during pregnancy and lactation
Valacyclovir is prescribed with caution during pregnancy/lactation after assessing the ratio of expected benefits to possible risks.
According to registration records of pregnancy outcomes in women who took Valaciclovir and other drugs containing acyclovir, there was no increase in the number of birth defects in their children compared to the general population. However, reliable and definite conclusions about the safety of the use of valacyclovir during pregnancy cannot be made, since only a small number of women who took valacyclovir during pregnancy are included in the registry.
special instructions
If you have kidney problems, use the drug with caution. Possible development of acute renal failure , disorders of the central nervous system.
For elderly patients, no dose adjustment is required, but the amount of fluid consumed should be increased.
During treatment for genital herpes, you should refrain from sexual intercourse, as the drug does not protect you from transmitting the virus to your partner.
Caution should be exercised when treating patients with liver disease.
There is no clinical experience with the use of the drug for children under 12 years of age; therefore, the medicine is not prescribed to children.
If the patient has undergone a bone marrow or kidney transplant, a clinically pronounced form of HIV infection , and acute immunodeficiency , then taking the drug can lead to thrombocytopenic purpura , hemolytic-uremic syndrome and death.
hallucinations, convulsions, agitation, confusion and delirium are observed during treatment with the drug , the drug should be discontinued.
Overdose
Main symptoms: vomiting, nausea, acute renal failure, neurological disorders (including hallucinations, confusion, depression of consciousness, agitation, coma). In most cases, the development of such conditions was observed in patients with impaired renal function and in elderly patients who received repeated doses of valacyclovir that exceeded the recommended dose, which was associated with non-compliance with the dosage regimen.
Therapy: Patients' condition should be closely monitored. The removal of acyclovir from the blood is greatly facilitated by hemodialysis; it can be considered the method of choice in the treatment of acyclovir overdose.
Valacyclovir analogs
Level 4 ATC code matches:
Herperax
Vivorax
Vairova
Acyclostad
Geviran
Walcyte
Valavir
Ribavirin
Valtrex
Valvir
Rebetol
Cyclovir
Famciclovir Teva
Famvir
The closest analogues: Vayora, Valaciclovir Canon, Valaciclovir hydrochloride, Valogard, Valcicon, Virdel, Valavir, Valvir, Valtrex, Vacirex .
Which is better: Valaciclovir or Valtrex?
Valtrex is an imported analogue with the same active ingredient. In terms of effectiveness and frequency of adverse reactions, the drugs are identical. However, the cost of Valtrex is significantly higher than Valaciclovir.
Which is better, Valaciclovir or Famvir?
Famvir is a Swiss antiviral drug that is available in three dosages. Positioned as an effective remedy against herpes simplex and herpes zoster.
The disadvantage of the drug is that it is prohibited for patients under 18 years of age, otherwise the list of contraindications and side effects and medications is the same. The price of the Swiss medicine starts at 1,300 rubles per package, which is twice as high as its Russian counterpart, so specialists often choose Valacyclovir, especially to combat the genital form of the disease.
Valacyclovir price
The price of Valaciclovir tablets in Russia is approximately 600 rubles for 10 pieces.
Together with tablets, as a rule, an ointment containing valacyclovir is used.
The price of Valacyclovir in Ukraine is slightly higher. You can buy the drug for 360 UAH (10 tablets).
- Online pharmacies in RussiaRussia
ZdravCity
- Valaciclovir tablets p.p.o.
500 mg 10 pcs. Izvarino Pharma LLC 811 rub. order - Valaciclovir tablets p.p.o. 500 mg 50 pcs. Izvarino Pharma LLC
RUR 2,446 order
- Valaciclovir tablets p.p.o. 500 mg 10 pcs. Ozone LLC
480 rub. order
- Valacyclovir Canon tablets p.p.o. 500 mg 10 pcs. CJSC Kanonpharma Production
340 rub. order
- Valaciclovir tablets p.p.o. 500 mg 10 pcs. JSC Sintez
415 rub. order
Preparations with the active ingredient - valacyclovir
Valacyclovir is the active ingredient. It is included in various drugs (from different manufacturers):
- Valaciclovir and Valcicon (manufacturer - Russia) - 500 mg tablets. Valaciclovir can be in higher concentrations - 1000 mg.
- Valavir (Ukraine) - 500 mg tablets.
- Vairova, Virdel, Valmik (Indian-made drugs) - 500 mg tablets, Valmik can also be 250 mg.
- Valaciclovir canon (Chinese valacyclovir) - 500 mg tablets.
- Valvir (drug produced in Iceland) - tablets in two dosages - 500 mg and 1000 mg.
- Valtrex (valacyclovir from Poland) - 500 mg tablets.
The price of the listed drugs may differ several times. At the same time, the active substance in them is the same, which means the therapeutic effect in the treatment of herpes is the same. Tablets from different manufacturers differ in additional binders, excipients, packaging and price.
Difference between Acyclovir and Valaciclovir
Both drugs are very similar in characteristics, so Valacyclovir and Acyclovir are usually prescribed for treatment. Patients do not understand what the difference is and often try to find out details from the doctor.
Typically, differences between drugs are important in certain situations, including the treatment of children under 3 years of age. In this case, Acyclovir is prescribed, since it has more flexible indications for use.
You can understand which is better, Valaciclovir or Acyclovir, by comparing the main characteristics. The main differences are the following parameters:
- Release form . Valaciclovir is available only in tablet form. Acyclovir can be purchased in different forms.
- Assimilation . Compared to Acyclovir, Valaciclovir is more quickly absorbed by the body.
- Duration of the course . If you take Valacyclovir in large dosages, complete recovery of the body will take less time than when taking Acyclovir. However, the final dosage and duration of therapy is determined by the attending physician.
If we compare both drugs, the short duration of administration and rapid absorption of Valacyclovir are significant advantages.
Indications and contraindications
Despite the rather narrow specificity of action, Valacyclovir is used in several directions. The drug is prescribed both for the appearance of small blisters on the lips and for the detection of genital herpes. The full list of indications includes:
- acute manifestations of herpes in the initial stages of the disease;
- relapses;
- exacerbation of chronic herpes;
- to prevent the transmission of sexually transmitted infections.
In some cases, it is necessary to start taking the medication within two days from the moment the first symptoms are detected. This applies to treatment or prevention:
- infectious diseases caused by herpes;
- cytomegalovirus infection.
A timely start of treatment affects the effectiveness of drug therapy. So, for herpes zoster, it is recommended to start taking the medication within the first 3 days from the moment the initial symptoms appear. This will help avoid the development of complications.
Valaciclovir is strongly not recommended if at least one of the possible contraindications is observed:
- hypersensitivity to the active substance or other components of the drug;
- organ transplantation within six months;
- weakened immune system;
- age less than 12 years when treating mild herpes;
- age less than 2 years and more than 18 years when treating chickenpox;
- genital herpes and herpes zoster in patients under 18 years of age;
- renal failure.
In such situations, only in extreme cases can a doctor prescribe Valacyclovir. Throughout the course, the patient must be under strict supervision so that in case of negative reactions of the body, the dosage of the drug can be adjusted within a short time.
Terms, conditions of sale and storage
The medication is dispensed only after providing a prescription from the attending physician. It is recommended to store the purchased product out of the reach of children at a temperature not exceeding 25 degrees.
Important! Exposure of tablets to direct sunlight is unacceptable.
The shelf life of the medicine is 3 years. It is not recommended to use the drug after the expiration date, since the effect of the expired drug on the body has not been studied.
