Types of Antivirals

Antiviral drugs are those used in the treatment of conditions caused by viral pathogens. They are somewhat like antibiotics used in the treatment of bacterial conditions. However, it is important to note that, since viruses are not "alive" (as are bacteria) antiviral drugs do not "kill" viruses, but interrupt their cycle of replication and infection at several different stages. Antiviral drugs currently are only used in the treatment of a limited number of viruses.

Use

• Antivirals interrupt the processes used by viruses in infecting host cells. This includes replication (reproduction), binding to and entering human cells, and integrating themselves into the genetic code of host cells. By interrupting these processes, it is possible to keep viral load (the number of copies of the virus present in the system) low, so the immune system can more effectively combat infection.

Herpetic Conditions

• A group of three major antiviral drugs are used in the treatment of herpetic conditions (such as genital and oral herpes, chickenpox, shingles and cytomegalovirus). These include acyclovir, valacyclovir and famciclovir. Valacyclovir uses acyclovir as its active ingredient, while famciclovir makes use of penciclovir; both valacyclovir and famciclovir operate more efficiently than acyclovir and thus can be taken less often. The dose and method of delivery for antiviral drugs used in herpetic conditions varies based on which condition an individual is experiencing.

Hepatitis B and C

• Antiviral drugs are also used in the treatment of hepatitis B and C. According to AVERT, an HIV/AIDS informational organization, antiviral medications are prescribed for those who develop chronic hepatitis B; these treatments include interferon alpha and lamivudine, according to the Hepatitis Foundation International. Pharmaceutical interferon is based on a body chemical that naturally fights off infections, while, according to GlaxoSmithKline, lamivudine is a nucleoside reverse transcriptase inhibitor that interferes with reverse transcriptase, with hepatitis B uses to make viral DNA for incorporation into host cells.

  Hepatitis C is treated with three different forms of interferon as well as ribavirin, which interferes with viral replication, according to the Hepatitis Foundation International.

Influenza A and B

• The Centers for Disease Control updates its guidelines every year on the antiviral treatment of influenza A and B, the strains of influenza that cause yearly flus. These drugs include Tamiflu and Relenza. According to its manufacturer, Roche, Tamiflu is a neuraminidase inhibitor, which interrupts the flu in its budding stage, part of replication; according to its manufacturer, GlaxoSmithKline, Relenza is also a neuraminidase inhibitor.

HIV

• A special group of antiviral drugs known as antiretrovirals is used in the management of HIV disease. Antiretroviral drugs are taken together in a therapy known as HAART (highly active antiretroviral therapy). This therapy combines three or more antiretroviral drugs that combat HIV at several stages. Classes of antiretroviral drugs include nucleoside and nonnucleoside reverse transcriptase inhibitors, which both interfere with reverse transcriptase, an enzyme used by HIV to make viral DNA to integrate into host cells; protease inhibitors, which target an enzyme, protease, that HIV uses to cut proteins in its replication process; smaller classes of drugs including fusion inhibitors, which interfere with HIV fusing with host cells; integrase inhibitors, which block integrase, the enzyme HIV uses to incorporate viral DNA into host DNA; and chemokine coreceptor antagonists, which bind to the coreceptor HIV uses in binding to host cells.