Summary
Antivirals are a class of medications that are used to treat viral infections. Most viral infections resolve spontaneously in immunocompetent individuals. The aim of antiviral therapy is to minimize symptoms and infectivity as well as to shorten the duration of illness. These drugs act by arresting the viral replication cycle at various stages. Currently, antiviral therapy is available only for a limited number of infections. Most of the antiviral drugs currently available are used to treat infections caused by HIV, herpes viruses, hepatitis B and C viruses, and influenza A and B viruses. Because viruses are obligate intracellular parasites, it is difficult to find drug targets that interfere with viral replication without also harming the host cells. Unlike other antimicrobials, antiviral drugs do not deactivate or destroy the microbe (in this case, the virus) but act by inhibiting replication. In this way, they prevent the viral load from increasing to a point where it could cause pathogenesis, allowing the body's innate immune mechanisms to neutralize the virus. This article provides an overview of the most commonly used antiviral agents. For more information on antiretroviral agents used in the treatment of HIV, which is known as highly active antiretroviral therapy (HAART), see HIV therapy.
Overview
Viruses are obligate pathogens, which depend on host-cell machinery for replication. Most antiviral agents target key enzymes required for viral replication (see viral life cycle for details).
Viral replication cycle and targets of antiviral drugs | ||
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Viral replication cycle | Target | Antiviral drug |
Fusion with host cell |
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Uncoating |
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Replication of viral genome |
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Protein synthesis and assembly of viral components | ||
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Release of new viruses from host cell |
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Antivirals against influenza viruses
Antiviral against influenza [1][2][3] | |||
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Agents | Mechanism of action | Indications | Adverse effects |
Amantadine Rimantadine |
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Oseltamivir Zanamivir Peramivir |
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Baloxavir marboxil |
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In influenza A and B, administration of neuraminidase inhibitors within 2 days of symptom onset is vital to reduce the duration of illness and alleviate symptoms.
Antivirals against herpes viruses
Antivirals against herpes [4][5][6] | ||||
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Agents | Mechanism of action | Indications | Adverse effects | Mechanism of antiviral resistance |
Acyclovir Valacyclovir (prodrug of acyclovir with greater oral bioavailability) Penciclovir Famciclovir (prodrug of penciclovir with greater oral bioavailability) |
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Ganciclovir Valganciclovir (prodrug of ganciclovir with greater oral availability) |
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Foscarnet (pyrophosphate analog) |
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Cidofovir |
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Fomivirsen |
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Antivirals against hepatitis B and C
See “Antiviral treatment of chronic hepatitis C” and “Antiviral treatment of chronic hepatitis B.”
Antivirals against both hepatitis B and C
Antivirals against both hepatitis B and C [7][8] | ||||
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Agents | Mechanism of action | Indications | Contraindications | Adverse effects |
Pegylated interferon-α and interferon-α |
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Antivirals against hepatitis B
Antivirals against hepatitis B only [8] | |||
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Agents | Mechanism of action | Indications | Adverse effects |
Tenofovir Adefovir |
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Entecavir Lamivudine Telbivudine |
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Antivirals against hepatitis C
Antivirals against hepatitis C only [7] | ||||
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Agents | Mechanism of action | Indications | Adverse effects | |
Ribavirin |
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Direct acting antivirals (DAAs) | Glecaprevir |
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Grazoprevir |
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Paritaprevir |
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Simeprevir |
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Voxilaprevir |
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Daclatasvir |
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Elbasvir |
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Ledipasvir |
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Ombitasvir |
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Pibrentasvir |
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Velpatasvir |
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Dasabuvir |
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Sofosbuvir |
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Protease inhibitors used to treat HIV end in ”navir.” Protease inhibitors used to treat HCV end in “previr.”