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Antivirals are drugs used to treat or prevent viral infections. Viruses cause major killer diseases around the world, accounting for huge numbers of deaths every year from diseases like the flu, HIV/AIDS and viral hepatitis. They are also causally linked to various cancers as in the case of HPV and cervical cancer, EBV and lymphoma and HBV and liver cancer.
The Flu.gov website mentions the use of antiviral agents in preventing flu infections in those exposed to the virus or facilitating recovery and preventing complications in those already sick with the flu virus. Antivirals continue to be the backbone of HIV/AIDS control in the absence of a vaccine.
How Antivirals Work
Viruses pose a challenge in treatment because of their peculiar nature of hijacking the normal cell functions to reproduce. Successful antivirals are those targeted at specific viral functions or structures. Viruses usually move through a life cycle of binding to the host cell and gaining entry, then removing their coat and releasing the genetic material. They then hijack cellular functions to produce viral components from the genetic material. The viral components are assembled into new infective units and finally released from the live cell or a broken-down cell.
Some antivirals, including Fuzeon, Relenza and Tamiflu, interfere with the binding of the virus to cells. They also interfere with the release of infective units from infected cells. Uncoating of the virus is blocked by agents like Symmetrel, Pleconaril and Flumadine. These agents also block the maturation of infective units, making them poorly effective.
The transcription and replication of viral genetic material, necessary for reproduction of viral components, can be blocked by agents like Valtrex and AZT. These agents are called DNA synthesis inhibitors. Some agents, including Zostex and Herpid confuse the process of genetic transcription, causing the production of faulty genetic material. Sustiva and similar agents irreversibly neutralize viral mechanisms of replication.
Production of viral components is also a target of anti-viral therapy. Vitravene confuses the production of viral proteins from viral genes. Drugs like Invirase, Crixivan and Viracept block the finishing process of viral protein synthesis, preventing the formation of components that can be assembled into viable infective units.
How anti-virals are used
Antivirals can be quite effective when given alone as seen in treatment of the flu with Tamiflu or Relenza. Some cases of development of resistance to the anti-virals by some viruses have prompted the use of antiviral combinations. The highly active anti-retroviral therapy (HAART) used for HIV/AIDS is one such case where several different anti-viral combinations are employed, for example AZT, lamivudine and Indinavir. The National Institute of allergies and Infectious diseases marks the HAART as a revolutionary approach in HIV/AIDS treatment.
Antivirals are prescribed to prevent infection in exposed susceptible individuals like health workers or patients with compromised immunity. They are also used in active treatment of viral infections to reduce severity of the illness, minimize complications and reduce transmission.
Antivirals can be prescribed for systemic use, as tablets, injections or infusions, in infections involving widespread areas of the body. There are also topical preparations that are applied as creams or eye drops.
