The Paxlovid molecule - rotatable in 3 dimensions

This substance, also known as PF-07321332, is a protease inhibitor. Its target is the 3C-like protease, the enzyme produced in coronavirus infected cells, which cleaves the coronavirus polyprotein at well defined positions, to release individual proteins, rather like cutting a string of sausages. These are non-structural proteins such as enzymes used by the virus in the infection cycle within body cells.
This is similar to protease inhibitor drugs which have proved so effective in treating infections by HIV.

The nitrile (cyano) group of the paxlovid molecule - its 'warhead' - forms a covalent bond with the amino acid cysteine in the active site of the protease enzyme and other groups block its substrate-binding pocket, preventing its usual hydrolytic action. The pyrrolidone group is said to simulate the R group of the amino acid glutamine, which marks the sites of action of the protease.

Paxlovid can be taken orally, whereas previous compounds needed to be to be administered intravenously. Interim results showed that combining the drug with ritonavir reduced the risk of hospitalization or death for adults with mild to moderate COVID-19 but at high risk of severe disease by 89% compared with a placebo. Its maker Pfizer plans to submit the data as part of its ongoing rolling submission to the U.S. FDA for Emergency Use Authorization (EUA).

Label/ Unlabel atoms

Supporting units on this site

HIV a section within the Cell recognition topic

Efavirenz Non-nucleoside reverse transcriptase inhibitor (NNRTI)

Ritonavir - an antiviral with several modes of attack

Web references

Covid: Pfizer says antiviral pill 89% effective in high-risk cases By Jim Reed and Philippa Roxby BBC News

Pfizer's Novel COVID-19 Oral Antiviral Treatment Candidate Reduced Risk of Hospitalization or Death by 89% in Interim Analysis of Phase 2/3 EPIC-HR Study

PF-07321332 From Wikipedia, the free encyclopedia

Crystal structure of SARS-CoV-2 main protease in complex with protease inhibitor PF-07321332 - good use of computer graphics