Protease inhibitors (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, hepatitis C and COVID-19. These protease inhibitors prevent viral replication by selectively binding to viral proteases and blocking proteolytic cleavage of protein precursors that are necessary for the production of infectious viral particles.
Ritonavir, sold under the brand name Norvir, is an antiretroviral medication used along with other medications to treat HIV/AIDS. This combination treatment is known as highly active antiretroviral therapy (HAART). Ritonavir is a protease inhibitor, though it now mainly serves to boost the potency of other protease inhibitors. It may also be used in combination with other medications to treat hepatitis C and COVID-19. It is taken by mouth.
The 3C-like protease (3CLpro) or main protease (Mpro), formally known as C30 endopeptidase or 3-chymotrypsin-like protease, is the main protease found in coronaviruses. It cleaves the coronavirus polyprotein at eleven conserved sites. It is a cysteine protease and a member of the PA clan of proteases. It has a cysteine-histidine catalytic dyad at its active site and cleaves a Gln–(Ser/Ala/Gly) peptide bond.
A deuterated drug is a small molecule medicinal product in which one or more of the hydrogen atoms in the drug molecule have been replaced by its heavier stable isotope deuterium. Because of the kinetic isotope effect, deuterium-containing drugs may have significantly lower rates of metabolism, and hence a longer half-life.
Narlaprevir, is an inhibitor of NS3/4A serine protease, intended for the treatment of chronic hepatitis C caused by genotype 1 virus in combination with other antiviral drugs.
Danoprevir (INN) is an orally available 15-membered macrocyclic peptidomimetic inhibitor of NS3/4A HCV protease. It contains acylsulfonamide, fluoroisoindole and tert-butyl carbamate moieties. Danoprevir is a clinical candidate based on its favorable potency profile against multiple HCV genotypes 1–6 and key mutants (GT1b, IC50 = 0.2–0.4 nM; replicon GT1b, EC50 = 1.6 nM). Danoprevir has been evaluated in an open-label, single arm clinical trial in combination with ritonavir for treating COVID-19 and favourably compared to lopinavir/ritonavir in a second trial.
Rupintrivir is a peptidomimetic antiviral drug which acts as a 3C and 3CL protease inhibitor. It was developed for the treatment of rhinoviruses, and has subsequently been investigated for the treatment of other viral diseases including those caused by picornaviruses, norovirus, and coronaviruses, such as SARS and COVID-19.
COVID-19 drug development is the research process to develop preventative therapeutic prescription drugs that would alleviate the severity of coronavirus disease 2019 (COVID-19). From early 2020 through 2021, several hundred drug companies, biotechnology firms, university research groups, and health organizations were developing therapeutic candidates for COVID-19 disease in various stages of preclinical or clinical research, with 419 potential COVID-19 drugs in clinical trials, as of April 2021.
3CLpro-1 is an antiviral drug related to rupintrivir which acts as a 3CL protease inhibitor and was originally developed for the treatment of human enterovirus 71. It is one of the most potent of a large series of compounds developed as inhibitors of the viral enzyme 3CL protease, with an in vitroIC50 of 200 nM. It also shows activity against coronavirus diseases such as SARS and MERS, and is under investigation as a potential treatment agent for the viral disease COVID-19.
TMC-310911 is an antiviral drug which was originally researched as a treatment for HIV/AIDS. It is a protease inhibitor related to darunavir. While TMC-310911 was not ultimately developed as a medication for the treatment of AIDS, research has continued into potential applications in the treatment of other viral diseases, and in March 2020 it was entered into clinical trials for the treatment of COVID-19.
GS-441524 is a nucleoside analogue antiviral drug which was developed by Gilead Sciences. It is the main plasma metabolite of the antiviral prodrug remdesivir, and has a half-life of around 24 hours in human patients. Remdesivir and GS-441524 were both found to be effective in vitro against feline coronavirus strains responsible for feline infectious peritonitis (FIP), a lethal systemic disease affecting domestic cats. Remdesivir was never tested in cats, but GS-441524 has been found to be effective treatment for FIP.
Eganelisib (USAN), codenamed IPI-549, is an experimental drug being investigated as a possible treatment for cancer. It is a highly selective phosphoinositide 3-kinase inhibitor, and thus works by inhibiting the enzyme PIK3CG, disrupting the PI3K/AKT/mTOR signaling pathway which plays important roles in the development of cancer.
Nirmatrelvir is an antiviral medication developed by Pfizer which acts as an orally active 3C-like protease inhibitor. It is part of a nirmatrelvir/ritonavir combination used to treat COVID-19 and sold under the brand name Paxlovid.
4-Propionoxy-N,N-dimethyltryptamine is a synthetic psychedelic drug from the tryptamine family with psychedelic effects, and is believed to act as a prodrug for psilocin. It produces a head-twitch response in mice. It has been sold online as a designer drug since May 2019. It was first identified as a new psychoactive substance in Sweden, in July 2019. A number of related derivatives have been synthesised as prodrugs of psilocin for medical applications.
Lufotrelvir (PF-07304814) is an antiviral drug developed by Pfizer which acts as a 3CL protease inhibitor. It is a prodrug with the phosphate group being cleaved in vivo to yield the active agent PF-00835231. Lufotrelvir is in human clinical trials for the treatment of COVID-19, and shows good activity against COVID-19 including several variant strains, but unlike the related drug nirmatrelvir it is not orally active and must be administered by intravenous infusion, and so has been the less favoured candidate for clinical development overall.
Nirmatrelvir/ritonavir, sold under the brand name Paxlovid, is a co-packaged medication used as a treatment for COVID‑19. It contains the antiviral medications nirmatrelvir and ritonavir and was developed by Pfizer. Nirmatrelvir inhibits SARS-CoV-2 main protease, while ritonavir is a strong CYP3A inhibitor, slowing down nirmatrelvir metabolism and therefore boosting its effect. It is taken by mouth.
Ensitrelvir, sold under the brand name Xocova is an antiviral medication used as a treatment for COVID-19. It was developed by Shionogi in partnership with Hokkaido University and acts as an orally active 3C-like protease inhibitor. It is taken by mouth.
Simnotrelvir/ritonavir is a pharmaceutical drug used for the treatment of COVID-19. Simnotrelvir/ritonavir is a combination drug of simnotrelvir, an inhibitor of SARS-CoV-2 3CLpro, and ritonavir, a CYP3A inhibitor.
Olgotrelvir (STI-1558) is an experimental antiviral medication being studied as a potential treatment for COVID-19. It is believed to work by inhibiting the SARS-CoV-2 main protease (Mpro), a key enzyme that SARS-CoV-2 needs to replicate, and by blocking viral entry.
Jun12682 is an experimental antiviral medication being studied as a potential treatment for COVID-19. It is believed to work by inhibiting SARS-CoV-2 papain-like protease (PLpro), a crucial enzyme for viral replication.
