Pharmacology - ANTIVIRAL DRUGS (MADE EASY)

Summary

This lecture provides an in-depth overview of antiviral drugs, categorized into four main groups: anti-influenza, anti-HIV, anti-hepatitis, and anti-herpes drugs. Each group is discussed in detail, covering mechanisms of viral infection and drug action. The lecture explains how antivirals target different stages of viral replication, including entry inhibitors, reverse transcriptase inhibitors, and protease inhibitors. Specific drugs and their mechanisms, such as M2 ion channel inhibitors for influenza and NS5A inhibitors for hepatitis C, are also covered. The video concludes with a discussion on the role of interferons and prodrugs in antiviral therapy.

Takeaways

• 💊 Antiviral drugs are classified into four groups: Anti-influenza, Anti-HIV, Anti-hepatitis, and Anti-herpes drugs.
• 🦠 Influenza is an enveloped virus with RNA genome, and drugs targeting it include M2 ion channel inhibitors, endonuclease inhibitors, and neuraminidase inhibitors.
• 🧬 Anti-influenza drugs like Amantadine and Rimantadine block the M2 channel, while Baloxavir inhibits cap-dependent endonuclease and Oseltamivir inhibits neuraminidase.
• 🧪 HIV primarily targets CD4+ T cells, and anti-HIV drugs are categorized as entry inhibitors, reverse transcriptase inhibitors, integrase inhibitors, and protease inhibitors.
• 🔑 Entry inhibitors like Enfuvirtide, Maraviroc, and Ibalizumab prevent HIV from binding and entering host cells.
• 🧫 Reverse transcriptase inhibitors are split into NRTIs (like Tenofovir and Lamivudine) and NNRTIs (like Efavirenz), both blocking viral RNA conversion to DNA.
• 🧩 Anti-hepatitis drugs, mainly nucleoside and nucleotide analogues like Entecavir and Tenofovir, inhibit hepatitis B virus DNA polymerase.
• 🧬 Direct-acting antivirals for hepatitis C target proteins NS3/4A, NS5A, and NS5B, with drugs like Sofosbuvir and Glecaprevir.
• 💉 Interferons, often paired with Ribavirin, are synthetic proteins used to treat chronic hepatitis by blocking viral protein synthesis.
• 🔗 Anti-herpes drugs, such as Acyclovir and Ganciclovir, are phosphorylated by viral thymidine kinase and inhibit viral DNA polymerase by causing DNA chain termination.

Q & A

What are the four main groups of antiviral drugs covered in the lecture?

The four main groups of antiviral drugs discussed are: (1) Anti-influenza drugs, (2) Anti-HIV drugs, (3) Anti-hepatitis drugs, and (4) Anti-herpes drugs.

How does the influenza virus enter the host cell?

The influenza virus binds its hemagglutinin (HA) protein to sialic acid residues on the host cell surface, resulting in endocytosis and entry into the cell.

What is the mechanism of action of M2 ion channel inhibitors in treating influenza?

M2 ion channel inhibitors, such as Amantadine and Rimantadine, block the M2 channel, preventing proton movement into the viral envelope. This stops the acidification of the viral core and the release of viral RNA into the host cell.

What are the three classes of drugs used to treat influenza, and how do they work?

The three classes are: (1) M2 ion channel inhibitors, which block viral uncoating; (2) Endonuclease inhibitors, like Baloxavir, which inhibit viral mRNA synthesis; (3) Neuraminidase inhibitors, such as Oseltamivir, Peramivir, and Zanamivir, which prevent viral release from infected cells.

How do entry inhibitors work against HIV, and what drugs are in this class?

Entry inhibitors block the binding, fusion, or entry of HIV into CD4 cells. Drugs in this class include Enfuvirtide, Maraviroc, and Ibalizumab, each working by preventing either viral fusion or interaction with host receptors.

What is the difference between nucleoside reverse transcriptase inhibitors (NRTIs) and non-nucleoside reverse transcriptase inhibitors (NNRTIs) in HIV treatment?

NRTIs are structural analogues of nucleic acids that cause chain termination during reverse transcription, while NNRTIs bind to and denature the reverse transcriptase enzyme, inhibiting it non-competitively.

What role do integrase inhibitors play in HIV therapy?

Integrase inhibitors, such as Dolutegravir and Raltegravir, block the viral integrase enzyme, preventing HIV from integrating its DNA into the host cell's genome.

How do anti-hepatitis B drugs inhibit the virus, and what class of drugs are used?

Anti-hepatitis B drugs are nucleoside and nucleotide analogues that inhibit viral polymerase, preventing reverse transcription and viral DNA synthesis. Examples include Entecavir, Lamivudine, and Tenofovir.

What are direct-acting antivirals (DAAs) used to treat hepatitis C, and what are the target proteins?

Direct-acting antivirals (DAAs) target specific hepatitis C virus proteins, such as NS3/4A protease, NS5A, and NS5B polymerase, inhibiting viral replication. Examples include Boceprevir (NS3/4A inhibitor), Ledipasvir (NS5A inhibitor), and Sofosbuvir (NS5B inhibitor).

How do anti-herpes drugs like Acyclovir work?

Anti-herpes drugs like Acyclovir are guanosine analogues that are phosphorylated by viral thymidine kinase. Once activated, they inhibit viral DNA polymerase by causing chain termination during DNA synthesis.