Covers antiviral agents grouped by mechanism, from blocking viral penetration and uncoating through nucleic acid synthesis inhibitors, integrase and protease inhibitors, neuraminidase inhibitors and immunomodulators, followed by selected adverse effects. The antifungal section moves through ergosterol inhibitors such as polyenes, azoles and allylamines, then cell wall and antimetabolite agents, with resistance notes. Two summary tables compare target organisms, mechanisms, resistance and side effects for representative drugs.
Topic 21 of 113 in the MU Sofia syllabus for Microbiology (Medicine, Year 3). The free AceMed note covers it in 3 sections, about 819 words (7 min of reading), with 15 flashcards.
In this note
Antiviral and Antifungal agents
Antiviral Agents
Antifungal Agents
Antiviral Agents
Mechanism of Action and Examples:
Inhibitors of Viral Penetration and Uncoating: These agents block the virus from entering or disassembling within the host cell.
Amantadine, Rimantadine: Block viral uncoating by inhibiting the viral protein M2 (H+ channel). Used for Influenza A. Their effectiveness is declining due to resistance. Administered orally.
Tromantadine: Used against Herpes Simplex Virus (HSV).
Ibalizumab: A monoclonal antibody that inhibits HIV adhesion.
Enfuvirtide: Blocks fusion of enveloped viruses with host cells.
Pocapavir: Prevents poliovirus uncoating.
Bropxexin: Blocks viral entry into cells, used for COVID-19.
Inhibitors of Nucleic Acid Synthesis (DNA/RNA Replication): These interfere with the production of new viral genetic material.
Nucleoside & Nucleotide Analogues: These are incorporated into viral DNA or RNA, blocking polymerase activity and causing "chain termination". They often require phosphorylation for activation.
Acyclovir, Valacyclovir: Inhibit viral DNA polymerase. Used for HSV and Varicella Zoster Virus (VZV).
Ganciclovir: Inhibits viral DNA polymerase. Used for Cytomegalovirus (CMV).
Ribavirin: Inhibits viral RNA polymerase. Used for CCHF, HFRS, and Hepatitis C (HCV). It has been tried in combination therapy for SARS (effectiveness uncertain) and is used for fulminant Hepatitis E (HEV) (contraindicated in pregnancy).
Remdesivir: Inhibits viral RNA polymerase by interfering with viral RNA synthesis. Used for COVID-19.
Lamivudine (3TC), Zidovudine (AZT), Tenofovir: These are Nucleoside Reverse Transcriptase Inhibitors (NRTIs). They act against HIV and Hepatitis B Virus (HBV). NRTIs cause chain termination of viral RNA.
Molnupiravir: Causes mutations in viral RNA, used for COVID-19.
Non-Nucleoside (Direct) Inhibitors: These do not require phosphorylation and directly inhibit polymerase or transcriptase.
Foscarnet (Phosphonoformate): Inhibits viral DNA polymerase. Used for CMV retinitis and also active against herpesviruses, HIV, and HBV.
Sofosbuvir, Daclatasvir: Inhibit viral RNA polymerase. Used for HCV.
Nevirapine, Efavirenz (EFV), Etravirine, Rilpivirine: These are Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs). Used against HIV.
Integrase Inhibitors: Prevent viral DNA from integrating into the host genome.
Raltegravir: An example used for HIV, including post-exposure prophylaxis.
Protease Inhibitors: Prevent viral replication by selectively binding to viral proteases, thereby inhibiting viral maturation and blocking viral protein synthesis.
Ritonavir, Indinavir: Examples used against HIV.
Ritonavir-boosted Nirmatrelvir (Paxlovid): Inhibits viral protease and is used for COVID-19, reducing hospitalization risk.
Neuraminidase Inhibitors: Inhibit the release of influenza viruses from host cells.
Oseltamivir (Tamiflu), Zanamivir (Relenza): Used for Influenza A & B and are effective within 48 hours of symptom onset.
Immunomodulators: Substances that enhance the immune response.
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