Antiviral drugs

Antiviral drugs are medicines that act on viruses by damaging their structures or disturbing vital functions.

At the present time, a sufficient number of such drugs have been developed. All of them are classified according to the peculiarities of pharmacological action and for specific medical indications. The following groups of antiviral agents are distinguished: extended spectrum, antiherpetic, anti-cytomegalovirus, anti-influenza, antiretroviral. The most famous representatives of the first type of medicines are "Ribavirin" and "Lamivudine". These drugs have complex mechanisms of action associated with the reduction of nucleic acids by binding to the enzymes of the virus. Based on the name, the scope of these medicines is quite broad and includes many DNA and RNA viruses that cause MS syndrome, Las's fever, hepatitis C, AIDS.

Antiherpetic preparations are represented by four agents, which in their morphological composition are analogues of nucleosides: acyclovir, penciclovir, famciclovir, valaciclovir. The last two dosage forms are inactive. In the human body, they are converted into acyclovir and penciclovir. This causes their close morphological and histological properties.

The mechanism of action of acyclovir is to interact with the enzymes of the virus, after which their development cycle is interrupted. The result is the death of this microorganism. Such interaction is provided by the structure of acyclovir, which is an analogue of deoxyguanedin (purine nucleoside). The most sensitive to this drug is herpes simplex virus. There are strains of microorganisms that are resistant to this drug. This effect can be explained by the use of immunosuppressive therapy. The mechanism of the emergence of resistance is the mutation of the enzyme systems of the virus, a change in the specificity of the drug. In the event of such situations use drugs from other pharmacological groups ("Foscarnet"). Children's antiviral drugs include "Valaciclovir." High bioavailability, which is more than fifty percent, causes a similar effect. This means that to achieve the effect, significantly lower doses of the drug are required (if compared with Acyclovir).

The mechanism of action of penciclovir practically does not differ from the preparations of its group. It also disrupts the synthesis of the DNA microorganism. However, it differs in that it affects the virus Varicella-Zoster (VZV) to a greater degree.

Antimegalovirus drugs include Ganciclovir, Valganciclovir, Foscarnet, Cidofovir, and Fomiversen. They have a rather complex mechanism of action, which consists in competitive inhibition of the DNA polymerase of the microorganism. The result of this interaction is a violation of the extension of the DNA chain, which leads to his death. The best antiviral drugs that eliminate the symptoms of cytomegalovirus infection are the drugs of this pharmacological group. However, after long-term use, drug resistance may develop, which somewhat reduces the range of their use.

Antiviral drugs can have a direct effect on the human immunodeficiency virus. Therefore, part of the medicines, which has a similar effect, were combined into an antiretroviral group. All of them have a complex mechanism of action, associated with the blocking of the enzyme systems of a given microorganism, a violation of its replication.