Prescribers MUST verify the patient's eligibility prior to prescribing nirmatrelvir/ritonavir
Treatment: Within 5 days of symptom onset
Before prescribing nirmatrelvir/ritonavir, clinicians should carefully review concomitant medications for drug interactions to reduce the risk of harm.
Drug interaction tools and resources:
Drug classes of particular concern are:
Questions to consider:
Potential management strategies:
Potential management strategies to facilitate the use of nirmatrelvir/ritonavir may differ depending on the magnitude and significance of the interaction. Options include:
These strategies should be considered for the 5-day duration of nirmatrelvir/ritonavir treatment and for at least 2 to 5 days after treatment completion (and for potentially longer if nirmatrelvir/ritonavir is administered with an interacting concomitant medication that has a long half-life).
Please note, the onset of inhibition is RAPID and clinically significant drug-drug interactions may occur despite the short treatment course.
The following medications should be avoided in combination with nirmatrelvir/ritonavir, they are either:
For more information please use the following tools & resources:
***Caution - the list below is only intended as a quick reference guide, and may not be complete.
Class | Medication |
---|---|
Alpha1-adrenoreceptor antagonist | alfuzosin |
Analgesics | meperidine, fentanyl |
Antiarrhythmics | amiodarone, disopyramide, dronedarone, flecainide, propafenone, quinidine |
Antibacterials | rifampin, rifapentine |
Anticancer | apalutamide, enzalutamide, neratinib, venetoclax |
Anticoagulant/ antiplatelet | ticagrelor, clopidogrel (significant reduction in antiplatelet activity, avoid if at very high-risk of thrombosis - review in interaction checker for more details) |
Anticonvulsants | carbamazepine, clonazepam, eslicarbazepine, oxcarbamazepine phenobarbital, phenytoin, primidone |
Antipsychotics | clozapine, lurasidone, pimozide, quetiapine |
Anxiolytics/hypnotics/ sedatives | alprazolam, diazepam, flurazepam, midazolam (oral), triazolam |
Anti-gout | colchicine |
Bronchodilators | salmeterol |
Ergot derivatives | dihydroergotamine, ergonovine, ergotamine |
Gastrointestinal agents | domperidone |
HCV DAAs | elbasvir/grazoprevir, glecaprevir/pibrentasvir |
Hypotension/Heart Failure Agents | aliskiren, bosentan, eplerenone, ivabradine, ranolazine |
Immunosuppressants | cyclosporine, sirolimus, tacrolimus, everolimus |
Lipid lowering agents | lovastatin, simvastatin, lomitapide |
PDE5 Inhibitors | sildenafil (PAH), tadalafil (PAH), vardenafil (PAH) |
Herbal/Natural Health Products | St John’s Wort |
-PAH - Pulmonary arterial hypertension
Adverse events (incidence ≥1% and ≥5 patient difference):
(studies are limited - possible that all adverse effects, including those that are rare but serious, are not known)
Pregnancy:
Breastfeeding:
Nirmatrelvir/ritonavir is recommended for patients with symptomatic mild-to-moderate illness at high risk of progression to severe COVID-19, including hospitalization and death.
Note: Asymptomatic patients should not be treated unless symptoms develop (follow-up is reasonable in patients who would qualify for treatment if otherwise symptomatic).
Patients must meet ALL the eligibility criteria and NONE of the exclusion criteria.
Definitions:
*Risk assessment tool adapted from BC COVID THERAPEUTICS COMMITTEE (CTC) Practice Tool #1 – Assessment Guide for Clinicians.
Administration:
Missed Dose:
Chewing/Crushing Tablets:
Usual Dosing (eGFR ≥ 60 mL/min):
Moderate renal impairment (eGFR ≥30 to <60 mL/min):
Severe renal impairment (eGFR <30 mL/min):
Intermittent hemodialysis (On dialysis days, administer dose after dialysis):
Health Canada Resources:
Drug Interaction Tools and Resources
Evidence Reviews and Summaries
Other Useful Practice Tools