Virus is a microscopic body that consists of proteins and nucleic acids. After penetrating living organism viruses infect healthy cells and cause their damage. Viruses are obligate parasites. It means that they are not able to replicate outside the living cells. The are lack of their own metabolic system and their multiplication and development depend only on host organism. Viruses represent molecules of nucleic acids (RNA or DNA) enclosed in capsid (protective protein shell). Viruses can contain only one type of nucleic acid: either DNA or RNA.
The Viral life cycle consists of the following mechanisms:
· Viral particles bind to host cells by connecting its capsulal glycoproteins to specific receptors located on the surface of cells
· Entering of viral particle into the host cells.
· Opening of viral capsule close to nuclear pores and motion of viral deoxyribonucleic acid (DNA) into the nucleus.
· Production of nucleic acid for synthesis of DNA (replication of genetic material) and RNA (protein synthesis). These proteins act as capsomers (viral enzymes) that catalyze viral multiplication or participate in formation of coat or incorporate into host cells.
· Accumulation of individual components into the new virus
· Release of new viruses out of infected cells and contamination of new healthy cells.
Antiviral drugs is a group of preparation that selectively act on different viral strains. The preparations affect different stages of viral life cycles in the host cells thus preventing the spread of the virus over the organism.
There are several groups of antiviral preparation classified according to chemical structure.
· Nucleosides such Aciclovir, Famciclovir, Valaciclovir, Ganciclovir. These drugs work by interfering with viral DNA synthesis and thus preventing their replication. These preparations are mostly used in treating of infections caused by Herpes Zoster, Herpes Simplex, Cytomegalovirus.
· Cyclic amines such as Amantadine, Rimantadine. This group of antiviral drug work by suppressing the early stages of viral replication by affecting the enzyme called RNA-trancriptase Cyclic amines are most frequently indicated in treatment of flu infections
· Neuraminidase inhibitors such as Zanamivir (Relenza), Oseltamivir (Tamiflu) - this group of medicines work by inhibiting certain viral enzyme called neuraminidase, thus preventing the spread of the virus over the body. By blocking this enzyme, Neuraminidase inhibitors limits the virus's ability to spread. This group of antiviral drugs is mainly indicated in treatment of flu infections.
· Specific group of antiviral drugs used in treatment of HIV. HIV drugs can be divided into the following drugs:
· HIV-protease inhibitors such as Idinavir, Ritonavir, Saquinavir, Darunavir. This group of medicine act by affecting certain enzyme of the virus and preventing the viral replication process.
· Reverse transcriptase inhibitors such as Zidovudine, Lamivudine - These drugs prevent viral replication by inhibiting the process of viral-DNA replication.
Other antiviral medications include: inosine pranobex, enfuviritide, raltegravir.
Viusid, oxolinic ointment, human recombinant interferon alpha-2 (Viferon), Arbidol (arpetol) are frequently used for the prophylaxis of flu infection.
Among the number of preparations mentioned above our online pharmacy may supply our customers with certain medicines used in flu and Herpes Simlex Hepres Zoster infections:
· Valcivir (generic Valtex)
· Zovirax (both generic and brand Zovirax by GSK)
· Tamiflu (generic Oseltamivir made by Cipla)