Nirmatrelvir (PF-07321332)

Nirmatrelvir (PF-07321332) is an orally bioavailable 3C-like protease (3CL^PRO) inhibitor that is the subject of clinical trial NCT04756531.[L33354] 3CL^PRO is responsible for cleaving polyproteins 1a and 1ab of SARS-CoV-2.[A234224] Without the activity of the SARS-CoV-2 3CL^PRO, nonstructural proteins (including proteases) cannot be released to perform their functions, inhibiting viral replication.[A234224,A234229,A234234] In 2020, Pfizer was investigating another potential treatment for SARS-CoV-2, [PF-07304814].[L33359] Both drugs were inhibitors of SARS-CoV-2 3CL^PRO, but nirmatrelvir has the advantage of being orally bioavailable.[L33359] Nirmatrelvir is advantageous in that it can be prescribed to patients before they require hospitalization, while [PF-07304814] requires intravenous administration in hospital.[L33359] In December 2021, the FDA granted an emergency use authorization to Paxlovid, a co-packaged product containing both nirmatrelvir and [ritonavir], for the treatment of certain patients with mild-to-moderate COVID-19.[L39544] It was fully approved by the FDA on May 25, 2023.[L46921] Paxlovid was approved for use in Canada in January 2022 for the treatment of adult patients with mild-moderate COVID-19 [L39544] and later granted conditional marketing authorization by the European Commission on January 27, 2022.[L40094]