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How Does a Protease Inhibitor Work?

Pfizer Hospital

Pfizer UK

In order to survive, all viruses have the same goal: to find a living host, invade its cells, use the cells’ internal machinery to make copies of itself and then release the newly made virus to infect more cells.1 This is known as the viral life cycle. 

But protease inhibitors, a class of medicines used to treat HIV and hepatitis C,2 have been shown to stop this process. Often in the form of an oral therapy, or a pill, these antiviral treatments work by blocking a critical enzyme (a protease) that the virus needs to be able to replicate.3

To put it simply, they disable the virus from making copies of itself so it can no longer continue to infect its host. 

Take a look behind the science to find out more:


  1. Cohen, F.S. (2016). How Viruses Invade Cells. Accessed March 2023.

  2. MedicineNet. Protease Inhibitors (PI) Drug Class. Accessed March 2023.

  3. Healthline. HIV: A Guide to Protease Inhibitors. Accessed March 2023. 

PP-UNP-GBR-4237 / March 2023
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