Antiviral drugs: classes, uses, mechanisms of actions and examples

Antiviral drugs are a group of drugs which have activities against infections of viral origin such as HIV/AIDS, Covid-19, hepatitis, herpes simplex virus disease etc. These substances or drugs have different ways they act, called mechanism of action, through which they inhibit viral growth, replication or entry into their hosts cells.

Classification of Antiviral drugs

Antiviral drugs can be broadly grouped into two major Classes

1. Antiretroviral drugs
2. Non-antiretroviral drugs

Antiretroviral drugs

This class of Antiviral drugs include all medications with activities against retroviruses infection, especially HIV. They are subgrouped, depending on their mechanisms of action, into:

1. Nucleoside Reverse Transcriptase Inhibitors (NRTIs)

This works against HIV by inhibiting NRT enzyme. Examples of this include:

2. Zidovudine
3. Lamivudine
4. Stavudine
5. Didanosine
6. Abacavir
7. Emtricitabine
8. Tenofovir
9. Zalcitabine

2. Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs)

This class, just like the name sounds, acts against HIV by inhibiting NNRT enzyme. Examples of NNRTIs include

2. Nevirapine
3. Efavirenz
4. Delavirdine
5. Etravirine
6. Rilpvirine

3. Protease Inhibitors (PIs)

This class of antiretroviral drugs works against HIV by selectively inhibiting the protease enzyme of the virus responsible for making of new viral particles inside CD4 cells. Examples of this include:

• Ritonavir
• Atazanavir
• Nelfinavir
• Indinavir
• Saquirnavir
• Amprenavir
• Lopinavir
• Darunavir
• Tipranavir
• Fortovase

4. Entry or Fusion Inhibitor

Just like the name, this class prevent HIV envelope from merging and therefore entering into new and healthy CD4 cell membrane in the body. Examples of this include:

• Enfuvirtide
• Maraviroc
• Ibalizumab
• Aplaviroc
• Vicriviroc

5. Integrase Inhibitor or Integrase Strand Transfer Inhibitors

This is a class of antiretroviral drugs that works against an Integrase enzyme of HIV. This enzyme enables HIV viral genome to be inserted into the DNA of human (or its host) CD4 cells. This drugs prevents HIV from replicating by its action as the viral genome that it prevents from being inserted into the host DNA dies off over time. An example of this include:

• Raltegravir
• Dolutegravir

Non-antiretroviral drugs

This second class of Antiviral drugs are a class that has Activities against non-retroviruses This class is further subdivided into:

1. Anti-Hepatitis virus drugs
   1. Anti-Hepatitis B Virus drugs
   2. Anti-Hepatitis C Virus drugs
2. Anti-influenza Virus drugs
3. Anti-herpes Virus drugs

Anti-Hepatitis Virus drugs

This classification is based on Activities not mechanism of action.

1. Hepatitis B Virus drugs examples are
   1. Lamivudine
   2. Tenofovir
   3. Adefovir dipivoxil
2. Hepatitis C Virus drugs
   1. Ribavarin
   2. Interferon alpha

Anti-influenza Virus drugs

Drugs under this class have Activities against influenza virus. They include:

• Amatadine
• Rimatadine
• Oseltamivir
• Zanamivir

Anti-herpes Virus drugs

These are a group of drugs with Activities against herpes virus. Examples of drugs in this group include:

• Acyclovir
• Valacyclovir
• Famciclovir
• Ganciclovir
• Valganciclovir
• Idoxuridine
• Trifluridine
• Cidoforvir
• Foscarnet and
• Fomivirsen