Antiviral agents
Last updated: October 18, 2024
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 “Overview of antiretrovirals for HIV treatment.”

Overview
Antivirals against hepatitis B and C
See “Antiviral treatment of chronic hepatitis C” and “Antiviral treatment of chronic hepatitis B.”
Antivirals against both hepatitis Band C
Overview of antivirals against both hepatitis B and C [1][2]
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Agents |
Mechanism of action |
Indications |
Contraindications |
Adverse effects |
Pegylated interferon alfa and interferon-α
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Antiviral and immunomodulatory effect via intercellular and intracellular mechanisms
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Overview of antivirals against hepatitis B [2]
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Agents |
Mechanism of action |
Indications |
Adverse effects |
Tenofovir Adefovir
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Entecavir Lamivudine Telbivudine
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Overview of antivirals against hepatitis C [1]
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Agents |
Mechanism of action |
Indications |
Adverse effects |
Ribavirin |
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Direct acting antivirals (DAAs)
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Glecaprevir |
- NS3/4A protease inhibitors
- Inhibition of NS3/4A (an HCV serine protease required for viral replication) → ↓ viral replication
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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 |
- Non-nucleoside NS5A polymerase inhibitors
- Exact mechanism of action is unknown
- Inhibition of the viral NS5A phosphoprotein, which is essential for replication → prevention of HCV RNA replication
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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.”
Antivirals against herpes viruses
Overview of antivirals against herpesviruses [3][4][5]
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Agents |
Mechanism of action |
Indications |
Adverse effects |
Mechanism of antiviral resistance |
Acyclovir Valacyclovir Penciclovir Famciclovir
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Ganciclovir Valganciclovir
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Foscarnet |
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Cidofovir |
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Fomivirsen |
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Antivirals against influenza viruses
Overview of antivirals against influenza viruses [6][7][8]
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Agents |
Mechanism of action |
Indications |
Adverse effects |
Amantadine Rimantadine
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Oseltamivir Zanamivir Peramivir
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- Neuraminidase inhibitor: inhibition of progeny release from the surface of infected host cells
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Treatment of influenza A and B (reduces symptom duration if taken within 1–2 days of symptom onset)
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Prophylaxis of influenza in adults and pediatric patients ≥1 year (oseltamivir) and ≥ 5 years (zanamivir) of age
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Baloxavir marboxil
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Treatment of influenza A and B (reduces symptom duration if taken within 48 hours of symptom onset)
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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.