Content
Most viral diseases present with flu-like symptoms of varying severity. Depending on the specific pathology, different antiviral agents can be used. Their classifications are based on the mechanism and spectrum of action, origin and some other criteria.
Classification of antiviral agents by mechanism of action
Groups of antiviral drugs according to this classification are distinguished taking into account the stage at which the virus interacts with the cell the drug begins to act. There are 4 options for how antiviral agents affect the body:
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Mechanism of action of antiviral agents |
Drug names |
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Blocking the penetration and release of the virus genome from the capsule inside the host cell. |
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Inhibition of the process of assembly of viral particles and their release from the cell cytoplasm. |
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Blocking viral RNA or DNA synthesis |
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Inhibition of virion assembly |
Metisazon. |
Types of antiviral drugs by spectrum of action
The difference between antiviral drugs is the selectivity of their action. Taking this into account, drugs are divided into types depending on the virus on which they are most capable of influencing. The classification of antiviral agents taking into account their spectrum of action is presented in the table:
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Funds group |
Name examples |
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Anti-flu |
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Broad-spectrum drugs |
These include interferons and interferonogens. |
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Medicines affecting human immunodeficiency virus |
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Antiherpetic |
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Against chickenpox virus |
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Anticytomegalovirus |
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Against hepatitis B and C virus |
Alpha interferons. |
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Antiretroviral |
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By origin
Different substances have antiviral properties, so drugs based on them are classified according to their origin. It distinguishes the following types of drugs:
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Funds group |
Examples of names |
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Nucleoside analogues |
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Lipid derivatives |
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Thiosemicarbazone derivatives |
Metisazon |
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Adamantane derivatives |
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Biological substances produced by the cells of a macroorganism |
Interferons. |
Classification according to M.D. Mashkovsky
The founder of Soviet pharmacology proposed his classification. According to it, antiviral drugs for children and adults were divided into the following groups:
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Group name |
Peculiarities |
Name examples |
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Interferons |
Interferons are cytokines, presented in the form of proteins that exhibit antitumor, immunomodulatory and antiviral properties. |
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Interferon inducers |
The antiviral effect of these drugs is to stimulate the production of your own interferon. |
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Immunomodulators |
When taking a therapeutic dose of immunomodulators, the function of the immune system is restored. |
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Derivatives of adamantane and other groups |
Affect human platelet aggregation. |
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Nucleosides |
These are glycosylamines containing a nitrogenous base. |
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Herbal preparations |
Obtained from plants. |
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Antiviral drugs are compounds of natural or synthetic origin used to treat and prevent viral infections. The action of many of them is selectively aimed at various stages of the development of viral infection and the life cycle of viruses.
Currently, more than 500 viruses are known to cause human diseases. Viruses contain single- or double-stranded ribonucleic acid (RNA) or deoxyribonucleic acid (DNA) enclosed in a protein shell called a capsid. Some of them also have an outer shell of lipoproteins. Many viruses contain enzymes or genes that enable reproduction in the host cell. Unlike bacteria, viruses do not have their own metabolism: they use the metabolic pathways of the host cell.
RNA viruses either synthesize messenger RNA (mRNA), or the RNA itself performs the function of mRNA. It synthesizes viral proteins, including RNA polymerase, with the participation of which viral mRNA is formed. Transcription of the genome of some RNA viruses occurs in the nucleus of the host cell. Under the influence of retroviral reverse transcriptase, complementary DNA (provirus) is synthesized based on viral RNA, which is integrated into the genome of the host cell. Subsequently, during transcription, both cellular RNA and viral mRNA are formed, on which viral proteins are synthesized for the assembly of new viruses. Viruses and the diseases they cause are shown in Table. 1.
Basic mechanisms of action of antiviral drugs
At the infection stage, the virus is adsorbed on the cell membrane and penetrates the cell. During this period, drugs are used that disrupt this process: soluble false receptors, antibodies to membrane receptors, inhibitors of the fusion of the virus with the cell membrane.
At the stage of virus penetration, when the virion is deproteinized and the nucleoprotein is “undressed,” ion channel blockers and capsid stabilizers are effective.
At the next stage, intracellular synthesis of viral components begins. At this stage, inhibitors of viral DNA polymerases, RNA polymerases, reverse transcriptase, helicase, primase, and integrase are effective. The translation of viral proteins is affected by interferons (IFN), antisense oligonucleotides, ribozymes and inhibitors of regulatory proteins. Proteolytic cleavage is affected by protase inhibitors.
IFN and inhibitors of structural proteins actively affect virus assembly.
The final stage of the replication cycle involves the release of daughter virions from the cell and the death of the infected host cell. At this stage, neuraminidase inhibitors, antiviral antibodies and cytotoxic lymphocytes are effective.
There are different classifications of antiviral agents. This article presents a classification based on the effect on a particular virus (Table 2).
Let's look at anti-influenza and anti-herpetic drugs.
Classification of antiviral drugs approved for use in Russia.
- group of anti-influenza drugs:
- Amantadine;
- Arbidol;
- Oseltamivir;
- Rimantadine. - Drugs acting on herpes viruses:
- Alpizarin;
- Acyclovir;
- Bonafton;
- Valaciclovir;
- Ganciclovir;
- Glycyrrhizic acid;
- Idoxuridine;
- Penciclovir;
- Riodoxol;
- Tebrofen;
- Tromantadine;
- Famciclovir;
- Florenal. - Antiretroviral drugs:
- Abacavir;
- Amprenavir;
- Atazanavir;
- Didanosine;
- Zalcitabine;
- Zidovudine;
- Indinavir sulfate;
- Lamivudine;
- Nelfinavir;
- Ritonavir;
- Saquinavir;
- Stavudin;
- Phosphazide;
- Efavirenz. - Other antiviral drugs:
- Inosine pranobex;
- Interferon alpha;
- Interferon alpha-2;
- Interferon alpha-2b;
- Interferon beta-1a;
- Interferon beta-1b;
- Yodantipyrine;
- Ribavirin;
- Tetraoxo-tetrahydronaphthalene (Oxolin);
- Tiloron;
- Flacoside.
Anti-influenza drugs (Table 2)
Arbidol is a derivative of indole carboxylic acid. The mechanism of action of the drug consists of suppressing the reproduction of the influenza virus, influencing the synthesis of IFN, increasing the number of T-lymphocytes and the functional activity of macrophages, as well as an antioxidant effect.
The drug penetrates unchanged into both uninfected and infected cells and is detected in the nuclear and cytoplasmic fractions. Arbidol inhibits the process of fusion of the lipid viral envelope with endosome membranes (at pH 7.4), leading to the release of the viral genome and the beginning of transcription. Unlike amantadine and rimantadine, Arbidol inhibits the release of the nucleocapsid itself from external proteins, neuraminidase and the lipid membrane. Thus, Arbidol acts in the early stages of viral reproduction.
The drug has no strain specificity (in cell cultures it suppresses the reproduction of the influenza A virus by 80%, the influenza B virus by 60% and the influenza C virus by 20%, and also affects the avian influenza virus, but weaker than the reproduction human strains of influenza virus).
IFN synthesis increases, starting from taking 1 tablet to 3 tablets. However, there is no further increase in IFN levels when taking Arbidol. A rapid increase in IFN synthesis can have a preventive effect when taken before the onset of influenza.
Arbidol has an immunomodulatory effect, leading to an increase in the total number of T-lymphocytes and T-helper cells. Moreover, normalization of these indicators was observed in patients with an initially reduced number of CD3 and CD4 cells, and in individuals with normal functioning of the cellular component of immunity there were practically no changes in the number of T-lymphocytes and T-helper cells. At the same time, the use of Arbidol does not lead to a significant decrease in the absolute number of T-suppressor lymphocytes - thus, the stimulating activity of the drug is not associated with inhibition of the function of suppressor cells. Arbidol increases the total number of macrophages with engulfed bacteria and the phagocytic number. It is assumed that the activating stimuli for phagocytic cells were cytokines and, in particular, IFN, the production of which is enhanced under the influence of the drug. The content of natural killer cells, NK cells, also increases, which allows the drug to be characterized as an inducer of natural killer cell activity.
The drug is quickly absorbed from the gastrointestinal tract (GIT). T1/2 is 16-21 hours. It is excreted unchanged in feces (38.9%) and urine (0.12%). During the first day, 90% of the administered dose is eliminated.
Drug interactions of Arbidol with other drugs have not been described in the literature.
Almost the only side effects of the drug are allergic reactions. The drug is approved for use from 2 years of age.
Arbidol has a fairly wide spectrum of antiviral action and is used for the prevention and treatment of influenza types A and B, including those complicated by bronchitis and pneumonia; acute respiratory diseases (ARVI); chronic bronchitis, pneumonia, recurrent herpes infection; in the postoperative period - to normalize the immune status and prevent complications.
Amantadine and rimantadine are adamantane derivatives. Both drugs, even in small doses, suppress the reproduction of virus A. Their antiviral activity is due to two mechanisms.
Firstly, they act at the early stage of viral reproduction, suppressing the “undressing” of the virus. The primary target for these drugs is the M2 protein of the influenza A virus, which forms an ion channel in its envelope. Suppression of the function of this protein leads to the fact that protons from endosomes cannot enter the virus, blocking the dissociation of the ribonucleide and the release of the virus into the cytoplasm.
Secondly, they can also act at the stage of virus assembly, apparently by changing the processing of hemagglutinin. This mechanism is possible in some strains of viruses.
Among wild strains, drug resistance rarely occurs, but resistant strains are obtained from patients taking them. The sensitivity and resistance of viruses to amantadine and rimantadine are cross-sensitivity.
Both drugs are well absorbed when taken orally and have a large volume of distribution. Most amantadine is excreted unchanged in the urine. The half-life (T 1/2) in young people is 12-18 hours, in the elderly it almost doubles, and in case of renal failure it increases even more. Therefore, the dose of the drug must be reduced even if there is a slight change in renal function. Rimantadine is actively metabolized in the liver, T1/2 is on average 24-36 hours, 60-90% of the drug is excreted in the urine in the form of metabolites.
When taking both drugs, minor dose-dependent disturbances in the gastrointestinal tract (nausea, loss of appetite) and central nervous system (CNS) (irritability, insomnia, impaired concentration) are most often noted. When taking high doses of amantadine, significant neurotoxic effects are possible: confusion, hallucinations, epileptic seizures, coma (these effects may be enhanced by simultaneous administration of H1-blockers, M-anticholinergics, psychotropic drugs and ethanol). Safety of use during pregnancy has not been established. Allowed for use from 7 years of age.
The drugs are used to prevent and treat influenza A. Their use during influenza epidemics allows one to avoid infection in 70-90% of cases. In persons with uncomplicated influenza A, treatment with drugs for 5 days in age-specific dosages, started at an early stage of the disease, reduces the duration of fever and general symptoms by 1-2 days, accelerates recovery and sometimes shortens the period of virus shedding.
Oseltamivir is an inactive precursor that is converted in the body to an active metabolite, oseltamivir carboxylate. It is a transition analogue of sialic acid and a selective inhibitor of neuraminidase of influenza A and B viruses. In addition, it suppresses strains of influenza A virus that are resistant to drugs derived from adamantane.
Neuraminidase of the influenza virus cleaves off the terminal residues of sialic acids and, thus, destroys receptors located on the surface of cells and new viruses, i.e., promotes the exit of the virus from the cell at the end of reproduction. The active metabolite of oseltamivir causes changes in the active center of neuraminidase and suppresses its activity. Viruses aggregate on the cell surface and their spread slows down.
Resistant strains of influenza A virus are found in 1-2% of patients taking the drug. To date, no resistant strains of influenza B virus have been detected.
When taken orally, the drug is well absorbed. Eating does not affect its bioavailability, but reduces the risk of side effects on the gastrointestinal tract. The drug undergoes enzymatic hydrolysis in the gastrointestinal tract and liver with the formation of an active metabolite. The volume of distribution of the drug approaches the volume of fluid in the body. Half-life of oseltamivir and its active metabolite is 1-3 and 6-10 hours, respectively. Both compounds are excreted primarily by the kidneys unchanged.
When taken orally, minor abdominal discomfort and nausea are possible, which decrease when taking the drug with food. Gastrointestinal disorders usually disappear after 1-2 days, even if the patient continues to take the drug. No clinically significant interactions of oseltamivir with other drugs have been identified. The drug is used in children over 1 year of age.
Oseltamivir is used to treat and prevent influenza. Prophylactic administration of oseltamivir during epidemics reduces the incidence both among those vaccinated with influenza vaccine and among unvaccinated people. When treating influenza with this drug, recovery occurs 1-2 days earlier, and the number of bacterial complications is reduced by 40-50%.
Antiherpetic drugs
Before moving on to a discussion of antiherpetic drugs, it is necessary to recall the various herpes viruses and the diseases caused by them (Table 4). Unfortunately, the arsenal of modern antiviral drugs does not contain drugs that act on all herpes viruses simultaneously (Table 5).
Herpes simplex virus type 1 causes damage to the skin, mouth, esophagus and brain; herpes simplex virus type 2 causes damage to the external genitalia, rectum, skin and meninges. The first antiherpetic drug approved for use was vidarabine (1977). However, due to its high toxicity, it was used to treat diseases caused by the herpes simplex virus and Varicella-zostervirus, only for health reasons. Since 1982, acyclovir has been used to treat patients with less severe disease.
Acyclovir is an acyclic analogue of guanosine, and valacyclovir is the L-valine ester of acyclovir. Acyclovir inhibits viral DNA synthesis after phosphorylation by viral thymidine kinase inside infected cells. The acyclovir triphosphate formed in the cell is integrated into the DNA chain synthesized in the host cell, which leads to the cessation of growth of the viral DNA chain. The DNA molecule, which contains acyclovir, binds to DNA polymerase, irreversibly inactivating it.
Viral resistance may result from decreased viral thymidine kinase activity and changes in viral DNA polymerase. Changes in enzyme activity occur as a result of mutations.
The bioavailability of acyclovir when taken orally is only 10-30% and decreases with increasing dose. Unlike acyclovir, the bioavailability of valacyclovir when taken orally reaches 70%. The drug is quickly and almost completely converted to acyclovir. Acyclovir penetrates into many biological fluids, including the contents of chickenpox vesicles, cerebrospinal fluid, and accumulates in milk, amniotic fluid and the placenta. Its concentration in vaginal contents varies widely. Serum concentrations of the drug in mother and newborn are approximately the same. The drug is practically not absorbed through the skin. T1/2 of acyclovir averages 2.5 hours in adults, 4 hours in newborns, and can increase to 20 hours in patients with renal failure. The drug is almost completely excreted unchanged by the kidneys. During pregnancy, the pharmacokinetics of drugs does not change.
As a rule, acyclovir is well tolerated. When using an ointment based on polyethylene glycol, irritation of the genital mucosa and a burning sensation are possible. When taken orally, the drug occasionally causes headache, dizziness, rash and diarrhea. Renal failure and neurotoxic effects are even less common. Side effects of valacyclovir are similar to those of acyclovir - nausea, diarrhea, headache; high doses may cause confusion, hallucinations, kidney damage and, very rarely, thrombocytopenia. With intravenous administration of large doses of acyclovir, renal failure and central nervous system damage may develop.
Famciclovir itself is inactive, but upon its first passage through the liver it is quickly converted to penciclovir. Penciclovir is an acyclic analogue of guanosine. The mechanism of action of the drug is similar to the mechanism of action of acyclovir. Like acyclovir, penciclovir acts primarily against herpes simplex viruses and Varicella-zostervirus. Resistance to penciclavir is rare in the clinic.
Unlike penciclovir, whose bioavailability when taken orally is only 5%, famciclovir is well absorbed. When taking famciclovir, the bioavailability of penciclovir increases to 65-77%. Eating together with the drug slows down the absorption of the latter, but in general the bioavailability is not reduced. The volume of distribution of penciclovir is 2 times the volume of fluid in the body, T1/21/2 increases to 9.9 hours. The drug is easily removed by hemodialysis.
Acyclovir is well tolerated, but sometimes headache, nausea, diarrhea, urticaria may occur, and in older people - hallucinations and confusion. Topical preparations may cause contact dermatitis and ulceration.
The safety of the drug during pregnancy, as well as its interaction with other drugs, has not been established.
Ganciclovir is an acyclic analogue of guanosine. The mechanism of action of the drug is similar to the mechanism of action of acyclovir. Active against all herpes viruses, but most effective against cytomegalovirus.
The bioavailability of ganciclovir when taken orally with food is 6-9% and slightly less when taken on an empty stomach. Valganciclovir is well absorbed and quickly hydrolyzed to ganciclovir, the bioavailability of which increases to 61%. When taking valganciclovir with food, the bioavailability of ganciclovir increases by another 25%. With normal renal function, T1/2 is 2-4 hours. More than 90% of the drug is excreted unchanged by the kidneys. In case of renal failure, T1/2 increases to 28-40 hours.
The main dose-limiting side effect of ganciclovir is inhibition of hematopoiesis (neutropenia, thrombocytopenia). In 5-15% of patients, central nervous system lesions of varying severity are noted (from headache to convulsions and coma). With intravenous administration, phlebitis, azotemia, anemia, rashes, fever, changes in liver biochemical parameters, nausea, vomiting, and eosinophilia are possible.
In laboratory animals, the drug had a teratogenic and embryotoxic effect and irreversibly impaired reproductive function. Cytotoxic drugs increase the side effects of ganciclovir on the bone marrow.
Idoxuridine is an iodine-containing analogue of thymidine. The mechanism of antiviral action is not fully understood. It is known that phosphorylated derivatives of the drug are incorporated into viral and cellular DNA, but only inhibit the replication of viral DNA. At the same time, DNA becomes more fragile, easily destroyed, and errors occur more often during its transcription. Resistant strains are isolated from patients with herpetic keratitis treated with idoxuridine. The drug is approved only for topical use. When using it, pain, itching, inflammation and swelling in the eye area, and allergic reactions are possible.
Advances in antimicrobial therapy in the 20th century led to almost complete control of bacterial infections. The task of infectious disease specialists and pharmacologists of the 21st century is to ensure control over viral infection. In addition to being highly effective, new antiviral drugs must be well tolerated. Currently, new agents with fundamentally new mechanisms of action are being developed. Means for suppressing pathological immune reactions and immunotherapy with monoclonal antibodies and vaccines may be promising.
N. M. Kiseleva, Candidate of Medical Sciences, Associate Professor
L. G. Kuzmenko, Doctor of Medical Sciences, Professor
RGMU, Moscow
The site provides reference information for informational purposes only. Diagnosis and treatment of diseases must be carried out under the supervision of a specialist. All drugs have contraindications. Consultation with a specialist is required!
What are antiviral drugs?
Antiviral drugs are medicines aimed at combating various types of viral diseases ( herpes, chicken pox, etc.). Viruses are a separate group of living organisms that can infect plants, animals and humans. Viruses are the smallest infectious agents, but also the most numerous.Viruses are nothing more than genetic information ( short chain of nitrogenous bases) in a shell of fats and proteins. Their structure is maximally simplified; they do not have a nucleus, enzymes, or energy supply elements, which makes them different from bacteria. That is why they have microscopic sizes, and their existence was hidden from science for many years. The existence of viruses passing through bacterial filters was first suggested in 1892 by the Russian scientist Dmitry Ivanovsky.
The number of effective antiviral drugs today is very small. Many drugs fight the virus by activating the body’s own immune forces. There are also no antiviral drugs that could be used in the case of a variety of viral infections; most existing drugs are narrowly aimed at treating one, maximum two diseases. This is due to the fact that viruses are very diverse; various enzymes and defense mechanisms are encoded in their genetic material.
History of the creation of antiviral drugs
The creation of the first antiviral drugs occurred in the middle of the last century. In 1946, the first antiviral drug, thiosemicarbazone, was proposed. It turned out to be ineffective. In the 50s, antiviral drugs appeared to combat the herpes virus. Their effectiveness was sufficient, but a large number of side effects almost completely excluded the possibility of its use in the treatment of herpes. In the 60s, amantadine and remantadine were developed, drugs that are still used today.All drugs until the beginning of the 90s were obtained empirically, using observations. Efficiency ( mechanism of action) these drugs were difficult to prove due to the lack of necessary knowledge. Only in recent decades have scientists obtained more complete data on the structure of the virus and its genetic material, as a result of which it became possible to produce more effective drugs. However, even today many drugs remain with clinically unproven effectiveness, which is why antiviral drugs are used only in certain cases.
A great success in medicine was the discovery of human interferon, a substance that carries out antiviral activity in the human body. It was proposed to be used as a medicine, after which scientists developed methods for purifying it from donor blood. Of all the antiviral drugs, only interferon and its derivatives can claim to be broad-spectrum drugs.
In recent years, the use of natural drugs to treat viral diseases has become popular ( for example echinacea). Also today, the use of various immunomodulatory drugs that provide prevention against viral diseases is popular. Their action is based on increasing the synthesis of its own interferon in the human body. A special problem of modern medicine is HIV infection and AIDS, so the main efforts of the pharmaceutical industry today are aimed at finding a treatment for this disease. Unfortunately, the necessary cure has not yet been found.
Production of antiviral drugs. The basis of antiviral drugs
There are a wide variety of antiviral drugs, but all of them have disadvantages. This is partly due to the complexity of developing, manufacturing and testing drugs. Antiviral drugs need to be tested, naturally, on viruses, but the problem is that viruses outside cells and outside other organisms do not live long and do not manifest themselves in any way. They are also quite difficult to identify. Unlike viruses, bacteria are cultivated in nutrient media, and the effectiveness of antibacterial drugs can be judged by the slowing of their growth.Today, antiviral drugs are obtained in the following ways:
- Chemical synthesis. The standard method of producing drugs is to obtain drugs through chemical reactions.
- Obtained from plant materials. Some parts of plants, as well as their extracts, have an antiviral effect, which is used by pharmacists in the production of medicines.
- Obtained from donor blood. These methods were relevant several decades ago, but today they have been practically abandoned. They were used to produce interferon. From 1 liter of donor blood, only a few milligrams of interferon could be obtained.
- Use of genetic engineering. This method is the latest in the pharmaceutical industry. Using genetic engineering, scientists change the structure of the genes of certain types of bacteria, as a result of which they produce the desired chemical compounds. They are subsequently purified and used as an antiviral agent. This is how, for example, some types of antiviral vaccines, recombinant interferon and other drugs are obtained.
Antiviral drugs, antifungals and antibiotics, differences. Can they be taken together?
Differences between antiviral, antifungal and antibacterial agents ( antibiotics) are implied in their name. All of them are created against different classes of microorganisms that cause diseases that differ in clinical manifestations. Naturally, they will be effective only if the pathogen has been correctly identified and the correct group of drugs has been selected for it.Antibiotics are directed against bacteria. Bacterial lesions include purulent lesions of the skin, mucous membranes, pneumonia, tuberculosis, syphilis, and many other diseases. Most inflammatory diseases ( cholecystitis, bronchitis, pyelonephritis and many others) is caused precisely by a bacterial infection. They are almost always characterized by standard clinical signs ( pain, fever, redness, swelling and dysfunction) and have minor differences. Diseases caused by bacteria constitute the largest group and have been studied most fully.
Fungal infections usually occur when the immune system is weakened and mainly affect the surface of the skin, nails, hair, and mucous membranes. The best example of fungal infections is candidiasis ( thrush). To treat fungal infections, only antifungal drugs should be used. The use of antibacterial drugs is a mistake, since fungi very often develop precisely when the balance of the bacterial flora is disturbed.
Finally, antiviral drugs are used to treat viral diseases. You can suspect that you have a viral disease by the presence of flu-like symptoms ( headache, body aches, fatigue, mild fever). This onset is typical for many viral diseases, including chickenpox, hepatitis and even intestinal viral diseases. Viral diseases cannot be treated with antibiotics; they cannot even be used to prevent the addition of a bacterial infection. However, it is worth considering that in the presence of simultaneous viral and bacterial infections, doctors prescribe drugs from both groups.
The listed groups of drugs are considered potent drugs and are sold only with a doctor's prescription. To treat viral, bacterial or fungal diseases, you should consult a doctor and not self-medicate.
Antiviral drugs with proven effectiveness. Are modern antiviral drugs effective enough?
There are currently a limited number of antiviral drugs available. The number of active ingredients with proven effectiveness against viruses is about 100 items. Of these, only about 20 are widely used in the treatment of various diseases. Others have either a high price or a large number of side effects. Some drugs have never undergone clinical trials, despite many years of practice. For example, only oseltamivir and zanamivir have proven effectiveness against influenza, despite the fact that pharmacies sell a large number of anti-influenza drugs.Antiviral drugs that have proven effectiveness include:
- valacyclovir;
- vidarabine;
- foscarnet;
- interferon;
- remantadine;
- oseltamivir;
- ribavirin and some other drugs.
In general, you need to be very careful when using antiviral drugs, especially those sold over the counter in pharmacies. Most of them do not have the necessary medicinal properties, and the benefits of their use are equated by many doctors to placebo ( a dummy substance that has no effect on the body). Viral infections are treated infectious disease doctors ( sign up) , in their arsenal there are the necessary drugs that definitely help against various pathogens. However, treatment with antiviral drugs should be carried out under the supervision of doctors, since most of them have significant side effects ( nephrotoxicity, hepatotoxicity, nervous system disorders, electrolyte disturbances and many others).
Can I buy antiviral drugs at the pharmacy?
Not all antiviral drugs can be purchased at the pharmacy. This is due to the serious effect of drugs on the human body. Their use requires permission and supervision from a physician. This applies to interferons, drugs against viral hepatitis, and systemic antivirals. To purchase a prescription drug, you need a special form with the seal of the doctor and medical institution. In all infectious diseases hospitals, antiviral drugs are provided without a prescription.However, there are various antiviral medications that can be purchased without a prescription. For example, ointments against herpes ( containing acyclovir), eye and nasal drops containing interferon and many other products are available over the counter. Immunomodulators and herbal antiviral drugs can also be purchased without a prescription. They are usually equated to dietary supplements ( dietary supplement).
Antiviral drugs according to their mechanism of action are divided into the following groups:
- drugs acting on extracellular forms of the virus ( oxolin, arbidol);
- drugs that prevent the virus from entering the cell ( remantadine, oseltamivir);
- drugs that stop the reproduction of the virus inside the cell ( acyclovir, ribavirin);
- drugs that stop the assembly and exit of the virus from the cell ( mixed breed);
- interferons and interferon inducers ( alpha, beta, gamma interferon).
Drugs acting on extracellular forms of the virus
This group includes a small number of drugs. One of these drugs is oxolin. It has the ability to penetrate the shell of a virus located outside cells and inactivate its genetic material. Arbidol affects the lipid membrane of the virus and makes it unable to merge with the cell.Interferon has an indirect effect on the virus. These drugs can attract immune system cells to the area of infection, which manage to inactivate the virus before it penetrates other cells.
Drugs that prevent the virus from entering the body's cells
This group includes the drugs amantadine and remantadine. They can be used against the influenza virus, as well as against the tick-borne encephalitis virus. These drugs have in common the ability to disrupt the interaction of the virus envelope ( in particular M protein) with a cell membrane. As a result, foreign genetic material does not enter the cytoplasm of the human cell. In addition, a certain obstacle is created during the assembly of virions ( virus particles).It is advisable to take these drugs only in the first days of the disease, since at the height of the disease the virus is already inside the cells. These drugs are well tolerated, but due to the peculiarities of the mechanism of action, they are used only for preventive purposes.
Drugs that block the activity of the virus inside the cells of the human body
This group of drugs is the widest. One way to stop the virus from reproducing is to block DNA ( RNA) – polymerases. These enzymes, brought into the cell by the virus, produce large numbers of copies of the viral genome. Acyclovir and its derivatives inhibit the activity of this enzyme, which explains their antiherpetic effect. Ribavirin and some other antiviral drugs also inhibit DNA polymerases.This group also includes antiretroviral drugs that are used to treat HIV. They inhibit the activity of reverse transcriptase, which converts viral RNA into cell DNA. These include lamivudine, zidovudine, stavudine and other drugs.
Drugs that block the assembly and release of the virus from cells
One of the representatives of the group is metisazon. This drug blocks the synthesis of the viral protein that makes up the virion envelope. The drug is used to prevent chickenpox, as well as to reduce complications of chickenpox vaccination. This group is promising in terms of creating new drugs, since the drug metisazon has pronounced antiviral activity, is easily tolerated by patients and is prescribed orally.Interferons. Use of interferons as medicine
Interferons are low molecular weight proteins that the body produces independently in response to infection with a virus. There are different types of interferons ( alpha, beta, gamma), which differ in various properties and the cells that produce them. Interferons are also produced during some bacterial infections, but these compounds play the greatest role in the fight against viruses. Without interferons, the immune system cannot function and the body cannot protect itself from viruses.Interferons have the following qualities that allow them to exhibit an antiviral effect:
- suppress the synthesis of viral proteins inside cells;
- slow down the assembly of the virus inside the body’s cells;
- block DNA and RNA polymerases;
- activate cellular and humoral immunity systems against viruses ( attracts leukocytes, activates the complement system).
Interferon inducers ( kagocel, trekrezan, cycloferon, amiksin)
The use of interferon inducers is an alternative to the use of interferons. Such treatment is usually several times cheaper and more accessible to consumers. Interferon inducers are substances that increase the body's production of its own interferon. Interferon inducers have a weak direct antiviral effect, but have a pronounced immunostimulating effect. Their activity is mainly due to the effects of interferon.The following groups of interferon inducers are distinguished:
- natural remedies ( amiksin, poludanum and others);
- synthetic drugs ( polyoxidonium, galavit and others);
- herbal preparations ( echinacea).
Antiviral drugs have a specific, selective effect. They are usually divided into types according to the virus on which they have the greatest impact. The most common classification involves dividing drugs according to their spectrum of action. This division facilitates their use in certain clinical situations. Types of antiviral drugs by spectrum of action
Pathogen | Most commonly used drugs |
Herpes virus |
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Influenza virus |
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Varicella zoster virus |
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Cytomegalovirus |
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Human immunodeficiency virus(HIV) |
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Hepatitis virus B and C |
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Paramyxovirus |
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Antiherpetic drugs ( acyclovir ( Zovirax) and its derivatives)
Herpes viruses are divided into 8 types and are relatively large viruses containing DNA. Manifestations of herpes simplex are caused by viruses of the first and second types. The main drug in the treatment of herpes is acyclovir ( Zovirax). It is one of the few drugs with proven antiviral activity. The role of acyclovir is to stop the growth of viral DNA.Acyclovir, entering a cell infected with a virus, undergoes a series of chemical reactions ( phosphorylated). The modified substance of acyclovir has the ability to inhibit ( stop development) viral DNA polymerase. The advantage of the drug is its selective action. In healthy cells, acyclovir is inactive, and against ordinary cellular DNA polymerase its effect is hundreds of times weaker than against the viral enzyme. The drug is used locally ( as a cream or eye ointment), and systemically in the form of tablets. But, unfortunately, only about 25% of the active substance is absorbed from the gastrointestinal tract when used systemically.
The following drugs are also effective in treating herpes:
- Ganciclovir. The mechanism of action is similar to acyclovir, but has a stronger effect, due to which the drug is also used in the treatment of tick-borne encephalitis. Despite this, the drug does not have a selective effect, which is why it is several times more toxic than acyclovir.
- Famciclovir. The mechanism of action is no different from acyclovir. The difference between them is the presence of a different nitrogenous base. In terms of effectiveness and toxicity, it is comparable to acyclovir.
- Valaciclovir. This medicine is more effective than acyclovir when used in tablet form. It is absorbed from the gastrointestinal tract in a fairly large percentage, and after undergoing a series of enzymatic changes in the liver it is converted into acyclovir.
- Foscarnet. The drug has a special chemical structure ( formic acid derivative). It does not undergo changes in the cells of the body, due to which it is active against strains of the virus that are resistant to acyclovir. Foscarnet is also used for cytomegalovirus, herpetic and tick-borne encephalitis. It is administered intravenously, which is why it has a large number of side effects.
Anti-flu drugs ( arbidol, remantadine, Tamiflu, Relenza)
There are many variants of influenza viruses. There are three types of influenza viruses ( A, B, C), as well as their division according to variants of surface proteins - hemagglutinin ( H) and neuraminidase ( N). Due to the fact that it is very difficult to determine the specific type of virus, anti-influenza drugs are not always effective. Anti-influenza drugs are usually used for severe infection, since in mild clinical manifestations the body copes with the virus on its own.The following types of anti-influenza drugs are distinguished:
- Inhibitors of viral protein M ( remantadine, amantadine). These drugs prevent the virus from entering the cell, therefore, they are mainly used as a prophylactic rather than a therapeutic agent.
- Inhibitors of the viral enzyme neuraminidase ( zanamivir, oseltamivir). Neuraminidase helps viruses destroy mucous secretions and penetrate the cells of the mucous membrane of the respiratory tract. Drugs in this group prevent the spread and replication ( reproduction) virus. One such drug is zanamivir ( release). It is used in aerosol form. Another drug is oseltamivir ( Tamiflu) – applied internally. It is this group of drugs that is recognized by the medical community as the only one with proven effectiveness. The drugs are tolerated quite easily.
- RNA polymerase inhibitors ( ribavirin). The principle of action of ribavirin does not differ from acyclovir and other drugs that inhibit the synthesis of viral genetic material. Unfortunately, drugs of this kind have mutagenic and carcinogenic properties, so they must be used with caution.
- Other drugs ( arbidol, oxolin). There are many other medications that can be used for the influenza virus. They have a weak antiviral effect, some additionally stimulate the production of their own interferon. However, it is worth noting that these drugs do not help everyone and not in all cases.
Drugs aimed at combating HIV infection
Treatment of HIV infection is one of the most serious problems in medicine today. The drugs that are available to modern medicine can only contain this virus, but not get rid of it. The human immunodeficiency virus is dangerous because it destroys the immune system, as a result of which the patient dies from bacterial infections and various complications.Drugs to combat HIV infection are divided into two groups:
- reverse transcriptase inhibitors ( zidovudine, stavudine, nevirapine);
- HIV protease inhibitors ( indinavir, saquinavir).
A relatively new group of antiretroviral drugs are protease inhibitors. They reduce the formation of enzymes and structural proteins of the virus, which is why immature forms of the virus are formed as a result of the life activity of the virus. This significantly delays the development of infection. One such drug is saquinavir. It inhibits the multiplication of retroviruses, but it also has the potential to develop resistance. That is why doctors use combinations of drugs from both groups in the treatment of HIV and AIDS.
Are there broad-spectrum antiviral drugs?
Despite claims from drug manufacturers and advertising information, there are no broad-spectrum antiviral drugs. The drugs that exist today and are recognized by official medicine are characterized by a targeted, specific effect. The classification of antiviral drugs implies their division according to the spectrum of action. There are some exceptions in the form of drugs that are active against 2 - 3 viruses ( for example, foscarnet), but nothing more.Antiviral drugs are prescribed by doctors in strict accordance with the clinical signs of the underlying disease. So, with the influenza virus, antiviral drugs intended for the treatment of herpes are useless. Drugs that can actually increase resistance ( resistance) of the body to viral diseases, are actually immunomodulators and have a weak antiviral effect. They are used primarily for prevention rather than treatment of viral diseases.
Interferons are also considered an exception. These drugs are allocated to a special group. Their action is unique, since the human body uses its own interferon in the fight against any viruses. Thus, interferons are indeed active against almost all viruses. However, the complexity of interferon therapy ( duration of treatment, the need to take it as part of courses, a large number of side effects) make it impossible to use it against mild viral infections. That is why interferons are used today mainly for the treatment of viral hepatitis.
Antiviral drugs - immunostimulants ( amiksin, kagocel)
Today, various drugs that stimulate the immune system are very common on the market. They have the ability to stop the growth of viruses and protect the body from infections. Such drugs are harmless, but do not have a direct effect against the virus. For example, Kagocel is an interferon inducer, which, after administration, increases the interferon content in the blood several times. It is used no later than the 4th day from the onset of infection, since after the fourth day the level of interferon increases on its own. Amixin has a similar effect ( tiloron) and many other drugs. Immunostimulants have many disadvantages that make their use inappropriate in most cases.The disadvantages of immunostimulants include:
- weak direct antiviral effect;
- limited period of use ( before the height of the disease);
- the effectiveness of the drug depends on the state of the human immune system;
- with prolonged use, the immune system is depleted;
- lack of clinically proven effectiveness of this group of drugs.
Herbal antiviral drugs ( echinacea preparations)
Herbal antiviral drugs are one of the best options in preventing viral infections. This is due to the fact that they do not have side effects like conventional antiviral drugs, and also do not have the disadvantages of immunostimulants ( immunodepletion, limited effectiveness).One of the best options for preventive use are preparations based on echinacea. This substance has a direct antiviral effect against herpes and influenza viruses, increases the number of immune cells and helps destroy various foreign agents. Echinacea preparations can be taken in courses lasting from 1 to 8 weeks.
Homeopathic antiviral remedies ( ergoferon, anaferon)
Homeopathy is a branch of medicine that uses highly diluted concentrations of the active substance. The principle of homeopathy is to use those substances that are expected to cause symptoms similar to the patient's disease ( the so-called principle of “treating like with like”). This principle is the opposite of the principles of official medicine. In addition, normal physiology cannot explain the mechanisms of action of homeopathic remedies. It is assumed that homeopathic remedies help in recovery by stimulating the neurovegetative, endocrine, and immune systems.Few suspect that some antiviral remedies sold in pharmacies are homeopathic. Thus, the drugs ergoferon, anaferon and some others belong to homeopathic remedies. They contain various antibodies to interferon, to histamine and to some receptors. As a result of their use, the connection between the components of the immune system improves and the speed of interferon-dependent protective processes increases. Ergoferon also has a slight anti-inflammatory and antiallergic effect.
Thus, homeopathic antiviral drugs have a right to exist, but it is advisable to use them as a preventive or auxiliary remedy. Their advantage is the almost complete absence of contraindications. However, treating severe viral infections with homeopathic remedies is prohibited. Doctors rarely prescribe homeopathic medicines to their patients.
Use of antiviral drugs
Antiviral drugs are quite diverse and differ in the method of administration. Various dosage forms should be used for their intended purpose according to the instructions. You should also observe the indications and contraindications for the use of drugs, since the benefits and harm to the patient’s health depend on this. For certain groups of patients ( pregnant women, children, patients with diabetes) you should be especially careful when using antiviral agents. The group of antiviral drugs has a large number of side effects, so their distribution and use are carefully controlled by the Ministry of Health. If the use of an antiviral drug causes side effects, you should immediately consult a doctor. He decides on the advisability of continuing treatment with this drug.
Indications for the use of antiviral agents
The purpose of using antiviral drugs comes from their name. They are used for various types of viral infections. In addition, some drugs from the antiviral category have additional effects that allow them to be used in various clinical situations not related to viral infection.Antiviral drugs are indicated for the following diseases:
- flu;
- herpes;
- cytomegalovirus infection;
- HIV/AIDS;
- viral hepatitis;
- tick-borne encephalitis;
- chicken pox;
- enterovirus infection;
- viral keratitis;
- stomatitis and other lesions.
Some antiviral agents have their own characteristics. Thus, interferons are used for cancer ( melanoma, cancer). They are used as chemotherapy agents to shrink tumors. Amantadine ( midantan), used to treat influenza, is also suitable for the treatment of Parkinson's disease and neuralgia. Many antiviral agents also have immunostimulating effects, but the use of immunostimulants is generally discouraged by the medical community.
Contraindications to the use of antiviral agents
Antiviral drugs have various contraindications. This is due to the fact that each drug has its own metabolic mechanisms in the body and affects organs and systems differently. In general, the most common contraindications to antiviral drugs include diseases of the kidneys, liver, and hematopoietic system.Among the most common contraindications to this group of drugs are:
- Mental disorders ( psychosis, depression). Antiviral drugs can negatively affect a person’s psychological state, especially during the first time of use. In addition, patients with mental disorders are at very high risk of inappropriate use of drugs, which is very dangerous for drugs with a large number of side effects.
- Hypersensitivity to one of the components of the drug. Allergies present a challenge to the use of any medication, not just antivirals. It can be suspected if there are other allergies ( for example, on plant pollen) or allergic diseases ( bronchial asthma). To prevent such reactions, it is worth undergoing special allergy tests.
- Hematopoietic disorders. Taking antiviral drugs can lead to a decrease in the number of red blood cells, platelets, and white blood cells. That is why most antiviral drugs are not suitable for patients with hematopoietic disorders.
- Severe pathology of the heart or blood vessels. When using drugs such as ribavirin, foscarnet, interferons, the risk of cardiac arrhythmia and an increase or decrease in blood pressure increases.
- Cirrhosis. Many antiviral drugs undergo various transformations in the liver ( phosphorylation, formation of less toxic products). Liver diseases associated with liver failure ( for example, cirrhosis) reduce their effectiveness, or, conversely, increase the duration of their presence in the body, making them dangerous for the patient.
- Autoimmune diseases. The immunostimulating effect of some drugs limits their use in autoimmune diseases. For example, interferons cannot be used for diseases of the thyroid gland ( autoimmune thyroiditis). When using them, the immune system begins to more actively fight the cells of its own body, which is why the disease progresses.
Release forms of antiviral drugs ( tablets, drops, syrup, injections, suppositories, ointments)
Antiviral drugs today are available in almost all dosage forms available to modern medicine. They are intended for both local and systemic use. A variety of forms are used so that the drug can have the most pronounced effect. At the same time, the dosage of the drug and the method of its use depend on the dosage form.Modern antiviral drugs are available in the following dosage forms:
- tablets for oral administration;
- powder for preparing a solution for oral administration;
- powder for injection ( complete with water for injections);
- ampoules for injections;
- suppositories ( candles);
- gels;
- ointments;
- syrups;
- nasal sprays and drops;
- eye drops and other dosage forms.
Most dosage forms allow the patient to independently accurately control the dose of the drug. However, when using some dosage forms ( ointment, gel, powder for the preparation of injection solution) you need to dose the drug correctly to avoid side effects. That is why the use of antiviral drugs in such cases should be carried out under the supervision of medical personnel.
Antiviral drugs for systemic and local use
There are a large number of forms of antiviral drugs that can be used both locally and systemically. This may even apply to the same active substance. For example, acyclovir is used either as an ointment or gel ( for topical application), and in tablet form. In the second case, it is used systemically, that is, it affects the entire body.Local use of antiviral agents has the following features:
- has a local effect ( on an area of skin, mucous membrane);
- as a rule, gel, ointment, nasal or eye drops, and aerosols are used for topical application;
- characterized by a pronounced effect in the area of application and lack of effect in distant places;
- has a lower risk of side effects;
- has virtually no effect on distant organs and systems ( liver, kidneys and others);
- used for influenza, genital herpes, lip herpes, papillomas and some other diseases;
- used for mild viral infections.
- used in case of generalized infection ( HIV, hepatitis), as well as in severe cases of the disease ( for example, with influenza complicated by pneumonia);
- has an effect on all cells in the human body, as it reaches them through the bloodstream;
- for systemic use, oral tablets, injections, and rectal suppositories are used;
- has a higher risk of side effects;
- In general, it is used in cases where local treatment alone is ineffective.
Instructions for the use of antiviral drugs
Antiviral drugs are quite powerful drugs. In order to achieve the desired effect from them and avoid side effects, you should follow the instructions for use of the drugs. Each medicine has its own instructions. The dosage form of the drug plays the greatest role in the use of antiviral drugs.The following are the most common ways of using antiviral drugs, depending on the dosage form:
- Pills. Tablets are taken orally during or after meals 1 to 3 times a day. The appropriate dosage is determined by taking the whole tablet or half of it.
- Injections. Must be performed by medical personnel, as incorrect administration can lead to complications ( including post-injection abscess). The drug powder is completely dissolved in liquid for injection and administered intramuscularly ( less often intravenously or subcutaneously).
- Ointments and gels. Apply a thin layer to the affected surface of the skin and mucous membranes. Ointments and gels can be used 3–4 times a day or even more often.
- Nasal and eye drops. Correct use of drops ( for example, influenzaferon) implies their administration in the amount of 1 – 2 drops in each nasal passage. They can be used 3 to 5 times a day.
- Drug dosage. The most important parameter, observing which you can avoid overdose. Antiviral drugs are usually taken in small concentrations ( from 50 to 100 mg of active ingredient).
- Frequency of use during the day. Antiviral tablets are taken 1 to 3 times a day, preparations for topical use ( drops, ointments) can be used 3 – 4 times a day or more often. When applied topically, overdose phenomena are very rare.
- Duration of use. The duration of the course is determined by the doctor and depends on the severity of the disease. Discontinuation of treatment with antiviral drugs should be carried out after examination by a doctor.
- Storage conditions. The storage temperature specified in the instructions must be observed. Some medications need to be stored in the refrigerator, others at room temperature.
Courses of antiviral drugs
Some antiviral drugs are used as part of long courses. Long-term use of drugs is necessary, first of all, for the treatment of viral hepatitis and HIV/AIDS. This is due to the high resistance of hepatitis and HIV viruses to drugs. Anti-hepatitis medications are taken for 3 to 6 months, anti-HIV medications for more than a year. Interferon and some other drugs are also used as part of course therapy.The duration of treatment for most antiviral drugs is no more than 2 weeks. During this time, flu, herpes, enterovirus infection and other viral diseases are usually cured. Another way to use antiviral drugs is prevention. If prophylactic purposes are pursued, the duration of taking antiviral drugs is from 3 to 7 days.
The most common side effects of antiviral drugs
Side effects from the use of antiviral drugs are really common. Naturally, the nature of the side effects largely depends on the drug itself, as well as its dosage form. Systemic drugs tend to create more side effects. Side effects are not common to all medications, but we can summarize and highlight the most common adverse reactions of the body to taking antiviral drugs.The most common side effects of antiviral drugs are:
- Neurotoxicity ( negative effect on the central nervous system). Expressed by headache, fatigue,
- Blocking the stage of penetration and release of the viral genome from the capsule inside the host cell - Rimantadine, Amantadine.
- Blocking the replication of viral DNA or RNA is most of the drugs used to kill viruses.
- Suppression of the process of assembly of viral particles in the cytoplasm of the cell and their release to the outside - interferons and HIV protease inhibitors.
These mechanisms of action are realized in the infected cell, and can often lead to its death. In most cases, such drugs do not damage a healthy cell. This is due to the fact that the metabolism of the cell infected with the virus is changed.
Unlike antibiotics, which gave medicine a new round of development in relation to the effective destruction of bacteria, with minimal side effects on the human body, most antiviral drugs do not have the same effectiveness and safety.
Antiviral agents - classification
The main clinical classification of these drugs is based on their primary purpose. Based on this criterion, the following groups are distinguished:
Almost all modern drugs are representatives of these main groups.
There are folk antiviral remedies, which are represented by various plants. Viburnum, raspberries, and currants are effective against most ARVI viruses.
Use of antiviral drugs
The use of this group of drugs is justified after laboratory diagnostics have been carried out and the exact type of virus that caused the infectious disease has been established. Today, several main drugs are used to treat various viral infections:
Antiviral drugs only have an effect on viruses in the replication stage. If viral DNA or RNA is inserted into the genome of a cell, but without the process of forming new particles, the drugs have no effect. In relation to ARVI and influenza, they have an effect only in the first 48-72 hours from the onset of the disease (the period of active replication).
When using such drugs, it is very important to observe the dosage, frequency of administration and duration of treatment. There are also antiviral drugs for children in age-appropriate dosages. In most cases, they are represented by drugs from the group of endogenous interferon stimulants, which have minimal side effects - children's Amizon, Amiksin, Anaferon. In case of severe viral infection, recombinant interferon (Laferon) is additionally used.
