<unk>  (PIs) are medications that act by interfering with enzymes that cleave proteins. Some of the most well known are antiviral drugs widely used to treat HIV/AIDS and hepatitis C. These<unk>  prevent viral replication by selectively binding to viral<unk> s (e.g. HIV-1<unk>  and blocking proteolytic cleavage of protein precursors that are necessary for the production of infectious viral particles.<unk>  that have been developed and are currently used in clinical practice include: * Antiretroviral HIV-1<unk>  — class stem ' * Amprenavir * Atazanavir * Darunavir * Fosamprenavir * Indinavir * Lopinavir * Nelfinavir * Ritonavir * Saquinavir * Tipranavir * Hepatitis C virus NS3/4A<unk>  — class stem ' * Asunaprevir * Boceprevir * Grazoprevir * Glecaprevir * Paritaprevir * Simeprevir * Telaprevir * Severe acute respiratory syndrome coronavirus 2 3-chymotrypsin-like<unk>  * Nirmatrelvir Given the specificity of the target of these drugs there is the risk, like with antibiotics, of the development of drug-resistant mutated viruses. To reduce this risk, it is common to use several different drugs together that are each aimed at different targets.
Protease inhibitor 
Exopeptidase inhibitor
Xanthine oxidase inhibitor
Endopeptidase inhibitor
Lipase inhibitors
Pharmacological chaperone
Polypeptide antibiotic
Quinolone antibiotic