Paxlovid (Nirmatrelvir/Ritonavir) Dosing and Frequency for Adults with COVID-19
The standard recommended dose of Paxlovid for adults with 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, 2
Standard Dosing Regimen
- Timing: Treatment must be initiated as soon as possible after diagnosis and within 5 days of symptom onset 2
- Administration: Take orally with or without food, at approximately the same time each day 1
- Duration: Complete 5-day course (10 total doses) 1
Dose Adjustments for Renal Impairment
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 1, 3
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: Administer dose after hemodialysis 1
Contraindications and Precautions
Contraindications
- History of clinically significant hypersensitivity to nirmatrelvir or ritonavir 1
- Co-administration with drugs highly dependent on CYP3A for clearance where elevated concentrations could lead to serious reactions 1
- Co-administration with potent CYP3A inducers that could reduce nirmatrelvir/ritonavir efficacy 1
Hepatic Impairment
- No dose adjustment needed for mild to moderate hepatic impairment
- Not recommended for patients with severe hepatic impairment (Child-Pugh Class C) 1
Drug Interactions
- Ritonavir is a strong CYP3A inhibitor that can significantly increase serum levels of many medications 2
- Before prescribing, review all patient medications to assess potential drug-drug interactions 2, 1
- Consider the benefit of Paxlovid treatment versus the risk of potential drug-drug interactions 1
Clinical Efficacy
- Paxlovid has shown an 86% reduction in hospitalization risk and significant mortality benefit compared to placebo in high-risk outpatients 2, 4
- Real-world data shows Paxlovid reduced the risk of hospitalization by 39% and death by 61% 4
- Effectiveness is maintained against Omicron subvariants 4
Common Adverse Effects
Pharmacokinetic Considerations
- Nirmatrelvir reaches maximum concentration of approximately 3.43 μg/mL in about 3 hours on day 5 of dosing 5
- When co-administered with ritonavir, renal elimination becomes the primary route of nirmatrelvir clearance 5, 3
Paxlovid represents a highly effective treatment option for COVID-19 when administered at the appropriate dose and timing. The dosing regimen must be adjusted based on renal function, and careful attention must be paid to potential drug interactions due to the ritonavir component.