Paxlovid Dosing for Patients with Normal Renal Function
For patients with normal renal function, the recommended dosage of Paxlovid is 300 mg nirmatrelvir (two 150 mg tablets) with 100 mg ritonavir (one 100 mg tablet), taken together twice daily for 5 days. 1
Dosing Details
The FDA-approved dosing for Paxlovid is based on renal function:
Normal renal function or mild renal impairment (eGFR ≥60 mL/min):
Moderate renal impairment (eGFR 30-59 mL/min):
- 150 mg nirmatrelvir (one 150 mg tablet) with 100 mg ritonavir (one 100 mg tablet)
- Taken twice daily for 5 days 1
Severe renal impairment (eGFR <30 mL/min):
- 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
Administration Guidelines
- Paxlovid should be initiated as soon as possible after diagnosis of COVID-19 and within 5 days of symptom onset 1
- Tablets can be administered with or without food 1
- Doses should be administered at approximately the same time each day 1
- For patients on hemodialysis, the dose should be administered after hemodialysis 1
Pharmacokinetic Considerations
The dose adjustments for patients with renal impairment are necessary because nirmatrelvir is primarily eliminated by the kidneys when given with ritonavir 3. A pharmacokinetic study showed that systemic nirmatrelvir exposure increases with decreasing renal function:
- Moderate renal impairment: 87% higher AUC compared to normal renal function 2, 3
- Severe renal impairment: 204% higher AUC compared to normal renal function 2, 3
Clinical Efficacy
When properly dosed according to renal function, Paxlovid has demonstrated significant clinical benefits:
- 89% reduction in COVID-19-related hospitalization or death when administered within 3 days of symptom onset 2
- Real-world data shows 39% reduction in hospitalization risk and 61% reduction in death risk 2
Important Considerations
- Ritonavir is a strong CYP3A4 inhibitor that can cause significant drug-drug interactions 2
- Before prescribing Paxlovid, assess for potential drug-drug interactions using resources like the Liverpool COVID-19 Drug Interaction Tool 2
- Certain medications are contraindicated with Paxlovid, including alfuzosin, amiodarone, and certain statins 2
- Common side effects include dysgeusia (altered taste, 5.6% of patients) and diarrhea (3.1% of patients) 2
The FDA-approved dosing recommendations are supported by population pharmacokinetic modeling and clinical studies that confirm the appropriate balance between efficacy and safety 4, 5.