Antiviral Medications Lecture Notes

Introduction

• Focus on antivirals similar to antibiotics.
• Coverage areas: HIV, influenza, hepatitis, herpes viruses.
• Usage of website resources for in-depth understanding.

Antiviral Medications Against HIV

Antiretroviral Therapies (ART)

• HIV: Retrovirus converting RNA to DNA.
• Target immune cells (T-helper/CD4+).

HIV Fusion and Entry Inhibition

• Proteins involved: GP41, GP120.
• Receptors involved: CD4, CCR5, CXCR4.
• Fusion inhibitors: Enfuvitide (blocks GP41-CD4 interaction).
• CCR5 inhibitors: Maraviroc (blocks GP120-CCR5 interaction).

Reverse Transcriptase Inhibition

• Reverse Transcriptase: Converts RNA to DNA.
• NRTIs (Nucleoside Reverse Transcriptase Inhibitors): Zidovudine, Abacavir, Lamivudine, etc.
• NNRTIs (Non-nucleoside Reverse Transcriptase Inhibitors): Nevirapine, Efavirenz, etc.

Integrase and Protease Inhibition

• Integrase Inhibitors: Dolutegravir, Raltegravir (prevent viral DNA integration).
• Protease Inhibitors: Ritonavir, Lopinavir, etc. (prevent protein processing).

Adverse Effects

• NRTIs: Mitochondrial toxicity, pancreatitis, nephrotoxicity, bone marrow suppression, hypersensitivity (Abacavir).
• NNRTIs: Hepatotoxicity, CNS effects, teratogenic (Efavirenz).
• Integrase Inhibitors: Rhabdomyolysis.
• Protease Inhibitors: Lipodystrophy, hyperglycemia, CYP450 inhibition.

HIV Treatment Regimen

• HAART (Highly Active Antiretroviral Therapy): Combination of drugs, primarily NRTIs and either NNRTI, integrase, or protease inhibitor.

Antiviral Medications Against Influenza

Mechanism of Action

• Hemagglutinin and neuraminidase: Key proteins.
• M2 ion channel: Involved in viral uncoating.

Influenza Treatment

• Amantadine: Blocks M2 channels (Influenza A).
• Baloxavir: Endonuclease inhibitor (blocks mRNA synthesis).
• Oseltamivir and Zanamivir: Neuraminidase inhibitors (prevent viral release).

Adverse Effects

• Amantadine: Ataxia, QT prolongation, skin manifestations.
• Others: Generally well-tolerated.

Antiviral Medications Against Hepatitis

Hepatitis B Treatment

• Reverse Transcriptase Inhibitors: Lamivudine, Entecavir, Tenofovir.
• Interferon Alpha: Enhances immune response.

Adverse Effects

• Interferon Alpha: Teratogenic, pancytopenia.
• NRTIs: Fanconi syndrome, other toxicities.

Hepatitis C Treatment

• Protease Inhibitors: Simeprevir, etc. (end in -previr).
• NS5A Inhibitors: Ledipasvir, etc. (end in -asvir).
• NS5B Inhibitors: Sofosbuvir, etc. (end in -buvir).
• Ribavirin: Used in refractory cases, inhibits inosine monophosphate dehydrogenase.

Adverse Effects

• Ribavirin: Teratogenic, hemolytic anemia.

Antiviral Medications Against Herpes

Mechanism of Action

• Viral DNA Polymerase Inhibitors: Cidofovir, Foscarnet.
• Guanosine Analogs: Acyclovir, Ganciclovir.

Adverse Effects

• Acyclovir/Valacyclovir: Nephrotoxicity, TTP.
• Ganciclovir: Bone marrow suppression.
• Foscarnet: Electrolyte disturbances, seizures.
• Cidofovir: Nephrotoxicity, mitigated by fluids and probenecid.

Conclusion

• Comprehensive overview of major antiviral classes, mechanisms, and key drugs.
• Importance of understanding drug interactions and adverse effects.