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Antiviral Drugs: Mechanisms, Therapeutic Uses, Adverse Effects, and Contraindications
Classification of Antiviral Drugs
- Inhibitors of Viral Entry and Uncoating: Amantadine, Rimantadine
- Nucleoside and Nucleotide Analogs: Acyclovir, Valacyclovir, Lamivudine, Tenofovir
- Protease Inhibitors: Ritonavir, Lopinavir, Atazanavir
- Neuraminidase Inhibitors: Oseltamivir, Zanamivir
- Integrase Inhibitors: Raltegravir, Dolutegravir
- Immune Modulators: Interferon-alpha, Ribavirin
Mechanisms of Action
- Inhibition of Viral Entry/Uncoating: Amantadine and Rimantadine block viral fusion with the host cell membrane, preventing uncoating.
- Inhibition of Nucleic Acid Synthesis: Nucleoside and nucleotide analogs like Acyclovir inhibit viral DNA/RNA replication by interfering with the polymerase enzyme.
- Inhibition of Viral Protease: Protease inhibitors like Ritonavir block the HIV protease enzyme, preventing viral maturation.
- Inhibition of Neuraminidase: Neuraminidase inhibitors like Oseltamivir prevent the release of viral particles from the host cell.
Therapeutic Uses
- Herpesvirus Infections: Acyclovir, Valacyclovir for Herpes Simplex Virus (HSV) and Varicella-Zoster Virus (VZV).
- Influenza: Oseltamivir, Zanamivir for the treatment and prevention of influenza A and B.
- HIV/AIDS: Lamivudine, Tenofovir, Ritonavir, Lopinavir for HIV infection.
- Hepatitis B and C: Lamivudine, Tenofovir, Ribavirin, Interferon-alpha for chronic hepatitis B and C infections.
- Chronic Hepatitis C: Ribavirin (often in combination therapy).
Adverse Effects
- Acyclovir/Valacyclovir: Nausea, vomiting, headache, and renal toxicity at high doses.
- Amantadine/Rimantadine: CNS effects like dizziness, confusion, hallucinations; dry mouth, urinary retention.
- Neuraminidase Inhibitors: Nausea, vomiting, diarrhea; rare neuropsychiatric effects.
- Protease Inhibitors: Gastrointestinal issues, liver toxicity, hyperglycemia, and hyperlipidemia.
- Interferons: Flu-like symptoms, depression, neutropenia.
Contraindications
- Amantadine: Contraindicated in patients with a history of seizures or psychiatric disorders.
- Protease Inhibitors: Contraindicated in patients with liver disease or certain cardiac conditions.
- Neuraminidase Inhibitors: Contraindicated in children under 2 years (Zanamivir), and those with respiratory issues.
- Ribavirin: Contraindicated during pregnancy and in women planning to become pregnant due to teratogenicity.
