Because ritonavir-boosted nirmatrelvir (brand name Paxlovid) is co-formulated with ritonavir as a pharmacologic booster, and ritonavir can alter levels of many drugs, clinicians should be aware of and identify any potential drug interactions. At the same time, NIH guidelines advise that “many drug-drug interactions between ritonavir-boosted nirmatrelvir and concomitant medications can be safely managed (e.g., for certain statins, calcium channel blockers or direct oral anticoagulants).”
The following resources may aid clinical decision-making:
IDSA Clinical Guide to Management of Nirmatrelvir/Ritonavir Drug Interactions
This clinical reference lists steps to take to minimize risk of interactions and provides information on the management of commonly prescribed medications that are known to interact with ritonavir-boosted nirmatrelvir.
FDA Patient Eligibility Screening Checklist Tool for Prescribers
This printable checklist includes a patient screening guide and lists drugs with established and/or potentially significant interactions. Drugs are listed as either contraindicated or as requiring additional management (i.e., avoiding and/or holding of the drug, dose adjustment or special monitoring).
NIH Guide to Drug-Drug Interactions Between Ritonavir-Boosted Nirmatrelvir & Concomitant Medications
This visual guide identifies outpatient medications that have clinically relevant drug-drug interactions and suggests several tiers of management strategies; it also lists commonly prescribed medications with no interactions that may be co-administered without dose adjustment/increased monitoring.
University of Liverpool COVID-19 Drug Interactions
This guide to COVID-19 medications and drug-drug interactions contains a helpful interaction checker, which provides a recommendation for management of drug-drug interactions in addition to a description of the primary data.
(See also Liverpool’s Quick Guide on Interactions with Outpatient Medicines and Paxlovid [PDF].)
University of Liverpool Patient Assessment Flowchart [PDF]
This flowchart provides considerations around assessing a patient for prescribing ritonavir-boosted nirmatrelvir.