What is the recommended dose of Paxlovid (nirmatrelvir/ritonavir) for COVID-19 treatment?

Recommended Dosing of Paxlovid for COVID-19

The standard recommended dose of Paxlovid for COVID-19 is 300 mg nirmatrelvir (two 150 mg tablets) with 100 mg ritonavir (one 100 mg tablet), with all three tablets taken together twice daily for 5 days. 1

Dosing Guidelines

Standard Dosing

• Nirmatrelvir 300 mg (two 150 mg tablets) plus ritonavir 100 mg (one 100 mg tablet)
• Administered orally twice daily for 5 days
• Can be taken with or without food
• Should be administered at approximately the same time each day
• Treatment should be initiated as soon as possible after diagnosis and within 5 days of symptom onset 2, 1

Dose Adjustments for Renal Impairment

1. Moderate renal impairment (eGFR ≥30 to <60 mL/min):

   • 150 mg nirmatrelvir (one 150 mg tablet) with 100 mg ritonavir (one 100 mg tablet) twice daily for 5 days 2, 1, 3

2. Severe renal impairment (eGFR <30 mL/min) including those requiring hemodialysis:

   • Day 1: 300 mg nirmatrelvir (two 150 mg tablets) with 100 mg ritonavir (one 100 mg tablet) once
   • Days 2-5: 150 mg nirmatrelvir (one 150 mg tablet) with 100 mg ritonavir (one 100 mg tablet) once daily 1
   • For patients on hemodialysis, the dose should be administered after hemodialysis 1

Hepatic Impairment

• No dose adjustment is needed for mild to moderate hepatic impairment
• Paxlovid is not recommended in patients with severe hepatic impairment (Child-Pugh Class C) 1

Clinical Efficacy

Paxlovid has demonstrated significant efficacy in reducing the risk of COVID-19 progression to severe disease:

• 89% reduction in risk of hospitalization or death when initiated within 3 days of symptom onset 4
• Significant reduction in viral load by day 5 of treatment 4
• Shorter nucleic acid shedding time (3.26 ± 1.80 vs 7.75 ± 3.68 days) compared to standard treatment 5

Important Considerations

Drug Interactions

• Ritonavir is a strong CYP3A inhibitor that can significantly affect the metabolism of many medications
• Prior to prescribing Paxlovid, review all medications taken by the patient to assess potential drug-drug interactions
• Some medications may require dose adjustment, interruption, or additional monitoring during Paxlovid treatment 1
• The Liverpool COVID-19 drug interaction tool is recommended as a resource for checking drug interactions 2

Common Adverse Effects

• Dysgeusia (altered taste) - 5.6% of patients
• Diarrhea - 3.1% of patients
• Most adverse events are mild in severity 4

Contraindications

• History of clinically significant hypersensitivity to nirmatrelvir or ritonavir
• Co-administration with drugs highly dependent on CYP3A for clearance
• Co-administration with potent CYP3A inducers 1

Special Populations

Pregnancy

• Paxlovid represents an option for pregnant people with COVID-19 to reduce the risk of disease progression
• Limited data on adverse reactions in pregnant or breastfeeding individuals 2

Timing of Treatment

Treatment should be initiated as early as possible in the course of the disease and within 5 days of symptom onset for optimal efficacy 2, 1, 4

Remember that Paxlovid is indicated for the treatment of mild-to-moderate COVID-19 in adults who are at high risk for progression to severe COVID-19, including hospitalization or death. It is not approved for pre-exposure or post-exposure prophylaxis.