Prescribing Information for ▼PAXLOVID (nirmatrelvir / ritonavir) can be found here. Adverse event reporting information can be found at the bottom of the page.
Paxlovid has a Conditional Marketing Authorisation in the United Kingdom. A Conditional Marketing Authorisation means that further evidence on this medicinal product is awaited. New information on this medicinal product will be reviewed when any relevant information of significance becomes available and at least every year and the product information will be updated as necessary.
See PAXLOVID in action
PAXLOVID's active pharmaceutical ingredient is nirmatrelvir, an oral protease inhibitor specifically designed by Pfizer to inhibit the main protease (Mpro), also known as 3-chymotrypsin-like cysteine (3CL) protease enzyme, and to help halt SARS-CoV-2 replication by preventing proteolysis from occurring.1
PAXLOVID also contains ritonavir, a CYP3A inhibitor that is widely used as a pharmacokinetic enhancer. Ritonavir is not active against SARS-CoV-2 3CL protease.1
1. Proteolysis
In the SARS-CoV-2 life cycle, proteolysis involves the cleavage of viral polyprotein chains by proteases to release the nonstructural proteins that are essential for viral replication.2
2. Mpro
Due to its essential function, Mpro is unlikely to mutate, as any mutations are more likely to create a virus that is unlikely to survive.3
3. Nirmatrelvir
Inhibition of Mpro by nirmatrelvir prevents proteolysis, helping to halt the viral replication cycle.1,3
Learn about the oral treatment schedule, dose adjustments and drug interactions.
Adverse Events
Adverse Events should be reported. Reporting forms and information can be found at https://coronavirus-yellowcard.mhra.gov.uk/ or search
for MHRA Yellow Card in Google Play or Apple App Store
Adverse events should also be reported to Pfizer Medical Information on 01304 616161
To access further materials, resources and receive communication about medicines and vaccines promoted by Pfizer.
This site is intended only for healthcare professionals resident in the United Kingdom. If you are a member of the public wishing to access information on a specific medicine, please visit www.medicines.org.uk/emc
This website is brought to you by Pfizer Limited, a company registered in England
and Wales under No. 526209 with its registered office at Ramsgate Road, Sandwich, Kent, CT13 9NJ
Copyright © 2025 Pfizer Limited. All rights reserved.
VAT registration number GB201048427
These pages are not intended for patients or for members of the general public. The healthcare professional web pages contain promotional content.
I confirm that I am a healthcare professional* resident in the United Kingdom.
If you select 'No', you will be redirected to Pfizer.co.uk where you will be able to access reference information on Pfizer's prescription medicines.
*The ABPI Code definition for healthcare professional is members of the medical, dental, pharmacy and nursing professionals and any other persons who in the course of their professional activities may administer, prescribe, purchase, recommend or supply a medicine.
PP-UNP-GBR-7812. January 2024.