Nirmatrelvir is an azabicyclohexane, specifically (1R,5S)-3-azabicyclo[3.1.0]hexane substituted with {(1S)-1-cyano-2-[(3S)-2-oxopyrrolidin-3-yl]ethyl}aminoacyl, 3-methyl-N-(trifluoroacetyl)-L-valinamide, methyl groups at positions 2S, 3, and 6. It is the first orally administered inhibitor of SARS-CoV-2 main protease developed by Pfizer, used in combination with ritonavir for COVID-19 treatment. It functions as an EC 3.4.22.69 (SARS coronavirus main proteinase) inhibitor and an anticoronaviral agent. It is a nitrile, a pyrrolidin-2-one, a secondary and tertiary carboxamide, a pyrrolidinecarboxamide, and an organofluorine compound.
