The FDA has authorized use of the nirmatrelvir/ritonavir, for the treatment of mild to moderate COVID-19. Studies have indicated that it is 88% effective at preventing hospitalization and death from COVID-19.

Criteria for Prescribing

To prescribe nirmatrelvir/ritonavir, prescribers should confirm that the following criteria have been met.

• A positive SARS-CoV-2 test.
• The patient is at least 12 years of age.
• The patient Weighs at least 40 kg (88lb).
• The patient has mild to moderate symptoms of COVID-19 who are not on supplemented oxygen but are at high risk of progression to moderate or severe Covid 19.
• Symptom onset within the past 5 days.
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Nirmatrelvir/Ritonavir is NOT authorized for use in the following patients.

• Patients hospitalized due to COVID-19
• For the pre-exposure or post-exposure prevention of COVID-19
• Patients with an allergy to either of its components
• Patients diagnosed with severe hepatic dysfunction (Child-Pugh Class C)

Choosing the appropriate dose

Dosing is based on renal function. If unable to determine a patient’s renal function, use best clinical judgment. For younger patients with no preexisting conditions or known renal dysfunction, it may be reasonable to prescribe therapy:

Renal Function & Dose

eGFR >60 mL/min     

300 mg nirmatrelvir (two 150 mg tablets) +100 mg ritonavir (one 100 mg tablet), taken in combination PO BID x 5 days

eGFR 30-60 mL/min  

150 mg nirmatrelvir (one 150 mg tablet) + 100 mg (ritonavir) (one 100 mg tablet), taken in combination PO BID x 5 days

eGFR <30 mL/min     

Avoid use

Side effects

Common side effects of Nirmatrelvir/Ritonavir are generally well tolerated and potentially include dysgeusia (taste disturbance), diarrhea, hypertension, myalgia, headache, and vomiting.

Drug-Drug Interactions (DDIs) considerations

Nirmatrelvir/Ritonavir has many potential drug-drug interactions. Carefully review the patient’s concomitant medications, including prescription, over-the-counter, medications, and herbal supplements.

Ritonavir is a potent CYP3A4 inhibitor and both ritonavir and nirmatelvir are both CYP3A4 substrates. Hence, the use of nirmatrelvir/ritonavir is contraindicated with the following drugs.

• Drugs that are highly metabolized by CYP3A4.
• Drugs that are potent CYP3A4 inducers, which may decrease the therapeutic effectiveness of nirmatrelvir/ritonavir.
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Special Populations

Patients on combined hormonal contraception

·       Use alternative effective contraception methods during nirmatrelvir/ritonavir treatment

·       Protease inhibitors may decrease the serum concentration of hormonal contraceptives.

Patients who are pregnant

There is limited research on the use of paxlovid in pregnancy.

·       In patients where there may be a potential pregnancy, a pregnancy test before treatment should be conducted.

·       Use of nirmatrelvir/ritonavir should not be withheld when potential benefits outweigh possible risks. Use may be considered in patients with additional risk factors, such as BMI >25, cardiovascular disease, chronic kidney disease, and diabetes mellitus.