Treatment of patients with COVID-19

Paxlovid (generic name: nirmatrelvir/ritonavir) is the preferred first-line therapy when safe and feasible for mild to moderate COVID-19 in patients at high risk of severe disease. Paxlovid is an oral antiviral medication composed of two drugs: nirmatrelvir (which stops viral replication) and ritonavir (which increases plasma concentrations of nirmatrelvir). It is a five-day course of tablets that can be taken at home. It has been demonstrated to reduce the risk of hospitalization in those who are at high risk for severe disease.

Paxlovid must be started within five days of symptom onset, where the first day of symptoms is day zero.

Physicians can consult pharmacists, as needed, to assess for potential drug interactions and to determine if they can be safely mitigated. Pharmacists can also prescribe Paxlovid to patients.

Testing 

Patients who are at high risk for severe disease must have a confirmed diagnosis of COVID-19 to be eligible for treatment with Paxlovid. Diagnosis can be confirmed by: 

• Lab-based PCR
• Rapid molecular test (e.g., ID NOW)
• Rapid antigen test, administered by the patient or health-care provider (note that a negative rapid antigen test does not rule out COVID-19) 

A positive rapid antigen test done at home and verified by the prescriber (in-person, virtual, picture or video) is acceptable. 

If you do not have the ability to test the patient in your practice: 

• You can order a publicly-funded PCR test for eligible patients using the Public Health Ontario test requisition

Access a list of testing locations.  

As a reminder, free rapid tests are available through the PPE supply portal for use in your practice, once you are enrolled in the Provincial Antigen Screening Program (PASP). You can enrol in PASP through the Ontario Together Portal. If you do not have an existing account, email sco.supplies@ontario.ca to get set up. Both rapid antigen tests and rapid molecular tests are available. Rapid antigen tests may also be available through public health units and participating health sector partners (e.g., pharmacies, hospitals and other health-care providers).

Prescribing 

A prescription for Paxlovid should include the following: 

• Dosing
• Confirmed COVID-19 (PCR or RAT+) 
• Duration of symptoms (should be five days or less, with symptom onset considered day zero) 
• Note that the patient is high risk for severe COVID-19
• Note on renal function or eGFR (if known) 
• List of current prescription and non-prescription medications (if known)
• Appropriate Limited Use (LU) code 

You can prescribe Paxlovid to patients for dispensing at a community pharmacy. Some pharmacists in the community can also prescribe and/or dispense Paxlovid to patients. You also have the option to put a Paxlovid prescription on file for your patient at their local pharmacy. Note that the patients will require a positive test to fill the prescription.

Renal and hepatic impairment

The standard dosing of Paxlovid should be adjusted for those with eGFR 30 to 59 ml/min. Dose adjustment for Paxlovid is recommended for individuals with eGFR les than 30 ml/min.

Paxlovid is not recommended for those with severe hepatic impairment (Child-Pugh Class C).

Read the Ontario Renal Network’s COVID-19 supplemental clinical guidance on Paxlovid use in patients with advanced chronic kidney disease and patients on dialysis with COVID-19.

Drug interactions 

Paxlovid interacts with many medications.  

• List of common medications and whether they interact with Paxlovid and how to manage (University of Waterloo)
• Online drug interaction checker (University of Liverpool) 
• Paxlovid Product Monograph with interactions and contraindications (Pfizer Canada)
• Paxlovid for a patient on direct oral anticoagulant (University of Waterloo)
• Management of Paxlovid interactions in oncology (University Health Network) 

Consult with specialists or other providers as needed to determine drug interactions(s) that can be safely mitigated. Pharmacists will also be checking for drug interactions at the point of dispensing. You can get information on drug interactions by calling the Ontario Pharmacists Association’s Respiratory Illness Support Line toll-free at 1-888-519-6069.

Dispensing and funding options

Paxlovid is available through participating community pharmacies, and they are encouraged to keep a supply of Paxlovid on hand. Should they not have Paxlovid in stock, pharmacists can place an order and/or are encouraged to help patients find a pharmacy that does so as part of their ethical obligation to ensure continuity of patient care.

Funding options include selected government drug benefit programs, private insurance or direct payment by the patient, consistent with funding models for other medications.  

Paxlovid is covered by the Ontario Drug Benefit (ODB) as a LU benefit for the treatment of mild to moderate COVID-19 for adults who are: 

• 65 years of age and older 
• Immunocompromised; and/or 
• 18 to 64 years of age with one or more risk factors for severe COVID-19

These patients must have a positive COVID-19 test (PCR or rapid antigen test) and symptoms within the past five days. 

If patients do not qualify for Paxlovid through the ODB Formulary, they can seek coverage through the Trillium Drug Program. Patients can apply for the Trillium Drug Program if they live in Ontario, having a valid Ontario health card number, and meet specific eligibility criteria about their current drug coverage and expenses. Refer to the Trillium Drug Program webpage for more eligibility and program information.

First Nations, Inuit, Métis and urban Indigenous people who live in Ontario may be eligible for this program as well as the Non-insured Health Benefit (NIHB). The LU criteria under the NIHB is similar to that of the ODB.

If patients are not eligible for coverage through drug benefits programs, they can seek coverage through their private insurance where applicable. If private insurance does not provide full or partial coverage, patients will need to pay for Paxlovid out of pocket. They can contact their local pharmacy for a price estimate.

Refer to Ontario Health released recommendations on Veklury (remdesivir) in adults.

Veklury (generic name: remdesivir) is an intravenous antiviral medication administered as a three-day course. It may also be available for patients at high risk of severe COVID-19 who cannot take Paxlovid or are beyond Paxlovid’s treatment window (greater than five days but within 7 days of symptom onset). 

Community- and hospital-based physicians can refer patients to their local Ontario Health atHome branch to receive remdesivir in the HCCSS clinic or their home. Appropriate referral forms and supporting documents must be completed and submitted to the local Ontario Health atHome branch. An Ontario Health atHome care co-ordinator will follow up with the patient. Remdesivir treatment is free of charge for patients with OHIP coverage (regardless of drug coverage). If patients do not have OHIP coverage, arrange for them to go to a local hospital or emergency department, or community nursing clinic directly, noting that there may be a cost to patients.