Paxlovid is an antiviral treatment that can be used for the treatment of patients with COVID-19. The science for this therapy can be confusing. Unfortunately, at this time, the Ontario Science Table Therapeutics Group has been paused. That means, while we relied upon this dedicated group to provide expert, science-based recommendations during the pandemic that were updated with very regular cadence, we cannot currently rely upon that.
At Osler in the Emergency Department, we are offering a curated set of resources for individual prescribers to consult around testing for COVID-19 and for how/when/where to prescribe the drug.
Excess supply of any drug should never be a justification for prescribing that drug. The decision to prescribe a drug should be made based on the evidence for benefit, risk of harm, and the individual patient in front of you.
Who is potentially eligible?
Patients with COVID-19 infection at high risk of severe outcomes within 5 days of symptom onset with mild disease who can be managed as an outpatient. Inpatient prescribing, albeit rare, can be left to the consulting service.
There are two broad views on this.
The OST Therapeutics Group takes a conservative approach. (this likely will not be updated) This is based on a 5% or higher risk of being hospitalized. The table linked here represents this approach.
The Ministry of Health and Ontario Health take a much broader approach based on “higher risk of severe outcomes.” The WHO recommendation has also recently been updated.
A positive test is required for treatment. Rapid Antigen Testing or PCR testing is sufficient. We encourage physicians and providers to use their judgement around testing. Rapid PCR testing should be reserved for urgent situations as it places a heavy burden on the laboratory staff.
Patients may be at higher risk of severe outcomes if they are:
- immunocompromised (have an immune system that is weakened by a health condition or medications);
- 70 years of age and older;
- 60 year of age and older with less than three vaccine doses; or
- 18 years of age or older with less than three vaccine doses and at least one risk condition.
Risk conditions are as follows:
- Obesity (BMI greater than or equal to 30 kg/m2)
- Diabetes
- Heart disease, hypertension, congestive heart failure
- Chronic respiratory disease, including cystic fibrosis
- Cerebral palsy
- Intellectual disability
- Sickle cell disease
- Moderate or severe kidney disease (eGFR below 60 mL/min)
- Moderate or severe liver disease (eg Child Pugh Class B or C cirrhosis)
- Some consider pregnancy a high risk condition (unvaccinated pregnant patients should receive ID consultation. Paxlovid is not safe in pregnancy.
What are the contraindications?
- There is a significant potential for drug-drug interactions. Review of medication history and pharmacy consultation is strongly recommended. For information on drug interactions, see COVID-19 Drug Interaction Tool. This reference from the Science Table is also excellent.
- Not recommended in pregnancy
- Dose adjustment required in renal dysfunction (included on the PDF prescription below)
- eGFR 30-59 mL/minute/1.73 m2 – Nirmatrelvir 150 mg / Ritonavir 100 mg PO BID
- eGFR less than 30 mL/minute/1.73 m2 – Not recommended
If I prescribe Paxlovid, where do patients acquire this?
The Ministry of Health is updated a list of pharmacies here.
A separate group has provided a Google Map link to the pharmacies with Paxlovid supply here.
Patients should call ahead. Most community pharmacies are stocking this drug at this time.
Special Populations – Transplant & Oncology
Oncology patients on active therapy or followed by oncology should be told to call the Oncology Clinic at Osler. The NPs and oncologists are familiar with drug-drug interactions and can prescribe the drug.
Transplant patients need very careful drug-drug interaction review and guidance. Connecting the patient with the transplant program or calling to speak to the person on call for their transplant physician may make sense. Most transplant programs are likely to resort to Remdesivir as the interactions are not manageable with Paxlovid.
How do I prescribe the drug?
You may wish to prescribe the drug. You may also wish to refer the patient to their family doctor or to a Community Assessment Centre. If you choose to prescribe the drug, we recommend using the prescription form below. It contains the liberal eligibility criteria.
Resources for Healthcare Providers
| Date | Resource Link |
| 1 April 2022 | Ontario Science Table Recommendations |
| 23 Feb 2022 | OST What prescribers and pharmacists need to know (interactions, etc.) |
| 4 April 2022 | Fillable PDF Prescription or Printable PDF Prescription |
| 11 April 2022 | Ministry of Health Antiviral Treatment Recommendations |
| Product Monograph (Pfizer) and Patient Information Sheet | |
| 17 Jan 2022 | Pfizer Resource: Paxlovid Summary |
| 22 April 2022 | WHO Revised Statement on Paxlovid |