Antiviral agents: characteristics, types, principle of action and application
Jul 07, 2018
Antiviral drugs are increasingly prescribed by doctors for various conditions and are used in home practice for self-treatment.What kind of drugs are they, how effective and harmless are they, is it worth using them?Can it still be better to return to traditional folk antiviral drugs - garlic, onions, lemon, milk with honey?After all, they have long been effectively treated with "colds", infectious and viral diseases, accompanied by a decrease in immunity?This will be discussed in our article.Table of contents: Mechanism of action of antiviral drugs Types of antiviral drugs Antiviral drugs against influenza
Mechanism of action of antiviral drugs
Antiviral drugs are isolated from anti-infectious medicines in a separate group.This is done because no other antimicrobial drugs( including such well-known antibiotics) are able to have an effective effect on the development of viruses.Such invulnerability of the virus is associated with their small and peculiarities of structure.For comparison, let's try to compare, say, the size of our planet and apple.So, the planet in our example is a medium-sized microbe, and the familiar apple is a virus.
Viruses consist of nucleic acids - sources of self-reproduction information and surrounding capsules.In the organism of the "host" they can multiply very quickly under favorable conditions, including by "embedding" their information in the cells of the diseased organism, which themselves begin to reproduce these pathogenic forms.The usual protective forces of human immunity( blood cells) are often powerless before them.The number of found pathogenic viruses is more than 500.
The first drug with antiviral properties was obtained in 1946, it was called Thiosemicarbazone.As the main component, he was part of the Pharyngocept, and for many years was used in clinical medicine to combat inflammatory diseases of the throat.Then discovered Idoxuridine, which is applied against the herpes virus.
Note: breakthrough in virology was the finding of human interferon - a protein that suppresses the vital activity of viruses.
Since the beginning of the 80s of the last century, active work has begun to create drugs that stimulate the ability of the body to synthesize interferon.
Scientific work continues in our time.Unfortunately, the cost of antiviral drugs is quite high.
Alas, but in the pharmaceutical market today, a large number of counterfeits - drugs that do not have protective or stimulating properties, in fact "placebo-dummies".
Types of antiviral drugs
All available antiviral drugs can be divided into 2 groups :
- Immunostimulants are drugs that can dramatically increase the production of interferons in a short-term manner.
- Antiviral drugs are medicines that can exert a direct inhibitory effect on the virus and block its reproduction.
According to the action on various types of viruses:
- antiviral drugs that have an effect on influenza viruses;
- medicines directed against the herpes virus;
- suppresses activity of retroviruses;
Please note : separately it is possible to distinguish a group of drugs intended for the treatment of HIV( immunodeficiency viruses).
Antiviral drugs against influenza
Amantadine and Remantadine
The effective antiviral agent against influenza is Amantadine .Amantadine is an inexpensive and effective antiviral.It in small doses is able to suppress the reproduction of the influenza type A virus at the earliest stage.
Amantadine blocks the flow of essential substances through the membrane of the virus and delays its release into the cytoplasm of the host cell.Also, this drug disrupts the normal process of developing a new synthesized virus.Alas, but with prolonged use of this drug, the stability of influenza viruses can form.
A similar action has another anti-influenza drug - Remantadine( Rimantadine).
Both these tools are endowed with a number of undesirable( side) effects.
On the background of their reception may arise:
- stomach and intestinal problems - nausea with vomiting, abdominal pain and appetite disorders;
- is a bad and nervous dream, a violation of concentration and attention;
- large doses can contribute to the appearance of altered consciousness, convulsive attacks, illusory phenomena down to hallucinations;
Important: Caution is required when taking pregnant.Children can be appointed not earlier than seven years of age.
According to clinical statistics, prophylactic drugs during the epidemic of influenza A prevent the development of the disease in 70-90% of cases of infection.
With the development of influenza, the use of amantadine or rimantadine reduces the duration of the disease, facilitates the course and reduces the period of virus isolation to the sick.
Anti-influenza remedy Arbidol
Arbidol is another drug related to the best antiviral drugs used against the flu. Has both a direct effect on the suppression of the reproductive qualities of the virus, and on the activation of the immune systems of the body, in particular T-lymphocytes and macrophages capable of fighting the flu.In addition, Arbidol increases the activity and the number of NK cells, specific "killer" viruses.In addition to these properties, it is a pronounced antioxidant.Has a preventive effect due to penetration into both infected cells and healthy ones.Has a broader antiviral effect.The range of its therapeutic effect also includes influenza B, C, as well as the causative agent of avian influenza.
Important: The antiviral drug has allergenic properties, which is a side effect.It is recommended as an antiviral agent for children from 3 years of age.
Admission of this drug has a positive effect and with complications of influenza, ARVI, bronchitis, pneumonia of viral origin, etc.
Features of the application of the antiviral agent Oseltamivir
Oseltamivir - in the body of a sick person is converted to an active carboxylate having inhibitory effect on the enzymes of influenza A, B viruses.
Its main distinguishing feature is that it actsOn strains resistant to Amantadine.Against the backdrop of the action of Oseltamivir, viruses lose the ability to actively spread.The number of resistant to it influenza A viruses is much less than that of previous drugs.It is most effective against influenza viruses B. It is excreted by the kidneys unchanged.
This anti-influenza drug may be accompanied by gastrointestinal disorders, which are significantly reduced if the drug is taken with food.It is recommended for treatment of all age categories.Including, it is used as part of antiviral drugs for children.Oseltamivir in the acute period of influenza significantly reduces the possibility of attaching bacterial complications - by about 40-50%.
Note: is the effective antiviral agent for colds treated.
Medical preparations with anti-herpetic properties
The most common is type 1 herpes virus, which appears on the skin, mucous membrane of the mouth, in the esophagus, in the membranes of the brain.
2 type of herpes causes pathological problems most often in the genital area, buttocks and rectum.
The first drug of this group was Vidarabin, obtained in 1977.However, along with effectiveness, he had a serious side effect and contraindications.Therefore, its use was justified only in very serious cases and was used according to vital indications.
In the early 80's, Acyclovir appeared.The main effect of this drug is to suppress the synthesis of DNA viruses by inserting into pathological DNA acyclovirtophosphate, stopping the growth of the virus.Valaciclovir works in a similar way. However, herpes viruses often develop resistance to these medicines.
Acyclovir, when applied internally, penetrates well into all tissues of the body.Drug tolerance is usually good, but intestinal disorders with vomiting and diarrhea may occur.Sometimes there is a headache, a disturbance of consciousness.Cases of development of renal failure are described.
It is used both inside and outward in the form of ointments.
Much less frequently, the resistance of herpes viruses is produced by the use of famciclovir and penciclovir.The mechanism of action on viruses in these drugs is similar to that of Acyclovir.Side effects are the same as in Acyclovir.
Ganciclovir is also similar to acyclovir by action.It is used to treat all types of herpes virus.
Note: Ganciclovir is a specific drug for the treatment of cytomegalovirus.
Important : requires constant monitoring of the blood test when the drug is used, since this drug can cause inhibition of the hematopoietic function and cause damage to the central nervous system.Use in pregnancy is prohibited because of damaging effects on the fetus.
In herpes zoster, Valaciclovir is indicated.
Mechanism of antiviral action of Idoxuridine is in the phase of study.This drug is used topically to treat herpetic eruptions.But it, in addition to antiviral effectiveness, gives frequent side effects in the form of pain, itching and swelling.
Interferon group preparations
Interferons are proteins secreted by cells of the body that are infected with viruses.Their main effect is the transfer of information about the need to activate the protective properties of the body to introduce pathological organisms.
Antiviral drugs of this group are:
- Viferon - is an antiviral agent available in the form of suppositories and ointments, has been used since 1996.Scientific evidence and clinical trials did not pass, but in practical medicine proved to be an effective drug in the treatment of herpetic eruptions in adults and children.
- Kipferon - is used mainly in cases of severe dysbiosis in children under 2 years old.Its main disadvantage is its high cost.It is produced in candles.
- Cycloferon - refers to agents that stimulate the production of interferon, while enhancing its antiviral activity.It is used in the form of injectable forms, ointments and in tablet form.Allowed to use for children over 4 years.Has a therapeutic effect in ARVI, viral hepatitis, papilloma viruses.Gives a positive effect for bacterial infections due to its immunostimulating action.
Note: is contraindicated in pregnant women and women during lactation.Studies on his actions are continuing.Has a high cost.
Work on the search for new low-cost antiviral drugs does not stop.Positive progress in this area indicates the need to develop this area of pharmacology further.
In conclusion, it should be noted that the group of antiviral drugs is still in the development stage, not all of the issues that are of interest to physicians have been clarified.The mechanism of action, effectiveness and side effects of already available drugs are not always well known, and the search for new effective ways of fighting viruses continues.
Faced with a viral illness, it is important not to resort to self-treatment.It is necessary to use drugs with proven efficacy and harmlessness, only on the advice of a doctor.
Please note: is especially careful to be the parents of small children.It is not always necessary to treat the baby antiviral drugs.
On the features of prescribing and using antiviral drugs for children in a video review, Dr. Komarovsky says:Lotin Alexander, radiologist