Antiviral agents; drugs that inhibit the replication or spread of viruses

Описание: Antiviral agents are drugs designed to prevent or treat infections caused by viruses. Unlike antibiotics (which target bacteria), antivirals act on specific stages of the viral life cycle—such as entry, replication, or release—without harming host cells.

🧬 Mechanism of Action
Viruses depend on host cell machinery, so antivirals target viral‑specific enzymes or processes:

Entry inhibitors – block virus attachment or penetration.

Uncoating inhibitors – prevent release of viral genome inside host cell.

Polymerase inhibitors – block viral DNA/RNA synthesis.

Protease inhibitors – prevent viral protein processing.

Integrase inhibitors – stop viral genome integration (HIV).

Neuraminidase inhibitors – prevent viral release (influenza).

Immune modulators – boost host defense (interferons).

💊 Major Classes & Examples
1. Anti‑Herpesvirus Drugs
Acyclovir, Valacyclovir, Famciclovir – inhibit viral DNA polymerase; used for HSV and VZV.

Ganciclovir, Valganciclovir – for CMV infections.

Foscarnet – for resistant HSV/CMV.

2. Anti‑Influenza Drugs
Oseltamivir, Zanamivir – neuraminidase inhibitors; reduce viral spread.

Baloxavir marboxil – cap‑dependent endonuclease inhibitor; blocks viral replication.

3. Anti‑HIV Drugs (Antiretrovirals)
NRTIs: Zidovudine, Lamivudine, Tenofovir.

NNRTIs: Efavirenz, Nevirapine.

Protease inhibitors: Lopinavir, Ritonavir.

Integrase inhibitors: Raltegravir, Dolutegravir.

Entry inhibitors: Maraviroc (CCR5 antagonist), Enfuvirtide (fusion inhibitor).

Therapy is combined as HAART (Highly Active Antiretroviral Therapy).

4. Anti‑Hepatitis Drugs
Hepatitis B: Tenofovir, Entecavir (nucleoside analogues).

Hepatitis C: Direct‑acting antivirals (DAAs) – Sofosbuvir (polymerase inhibitor), Ledipasvir (NS5A inhibitor), Simeprevir (protease inhibitor).

Interferon‑α: older therapy, now less common.

5. Other Antivirals
Ribavirin – broad‑spectrum; used for RSV, viral hemorrhagic fevers.

Remdesivir – RNA polymerase inhibitor; used in COVID‑19.

Favipiravir – RNA polymerase inhibitor; investigational for influenza and emerging viruses.

#Antiviral