Contact UsInvestorsCareersMediaScienceContact Us

Pfizer Canada Initiates Submission to Health Canada for Covid-19 Oral Antiviral Candidate


December 1, 2021 – Pfizer Canada today initiated the filing of a rolling New Drug Submission (NDS) with Health Canada for its investigational oral antiviral candidate PF-07321332; ritonavir, for the treatment of mild to moderate COVID-19 in adults at increased risk of hospitalizations or death.

This submission includes clinical data from the Phase 2/3 EPIC-HR (Evaluation of Protease Inhibition for COVID-19 in High-Risk Patients) interim analysis. This trial enrolled non-hospitalized adults aged 18 and older with confirmed COVID-19 who are at increased risk of progressing to severe illness.

About PF-07321332; ritonavir

PF-07321332 is designed to block the activity of the main SARS-CoV-2 protease, an enzyme essential for viral replication. Co-administration with a low dose of ritonavir is expected to help slow the metabolism, or breakdown, of PF-07321332 in order for it to remain active in the body for longer periods of time at higher concentrations to help combat the virus. Ritonavir has been used extensively in combination with other antivirals to help slow metabolism in a similar way.

The EPIC (Evaluation of Protease Inhibition for COVID-19) Phase 2/3 development program for PF-07321332 consists of multiple clinical trials: one in SARS-CoV-2 infected adults who are at high risk of severe illness (including hospitalization or death), a second in infected, symptomatic adults who are at standard risk (i.e., do not have risk factors for severe illness), and a third aimed at preventing development of SARS-CoV-2 infections in adult household contacts of symptomatic COVID-19 patients. 

About Pfizer Canada

Pfizer Canada ULC is the Canadian operation of Pfizer Inc., one of the world's leading biopharmaceutical companies. Our diversified healthcare portfolio includes some of the world's best known and most prescribed medicines and vaccines. We apply science and our global resources to improve the health and well-being of Canadians at every stage of life. Our commitment is reflected in everything we do, from our disease awareness initiatives to our community partnerships. To learn more about Pfizer Canada, visit or you can follow us on LinkedIn, Facebook, Twitter or YouTube.

For more information:

Pfizer Canada Corporate Affairs

1-866-9-PFIZER (1 866 973-4937)

[email protected]

About UsOur ProductsHelping Communities Our Voice Suppliers Distribution ChannelPfizer WorldwideMedia CentreTerms Of Use Careers Healthcare ProfessionalsContact UsPrivacy PolicyCopyright © Pfizer Canada 2022 All rights reserved. The information is intended only for residents of Canada. ® Pfizer Inc, used under license