What is the normal dose of Paxlovid (nirmatrelvir and ritonavir) for an adult patient with COVID-19 and normal kidney function?

Normal Paxlovid Dose

For adults with COVID-19 and normal kidney function, the standard dose of Paxlovid is nirmatrelvir 300 mg (two 150 mg tablets) plus ritonavir 100 mg (one 100 mg tablet) taken together twice daily for 5 days. 1, 2

Standard Dosing Regimen

• Administer 300 mg nirmatrelvir with 100 mg ritonavir orally every 12 hours for 5 consecutive days 1, 2
• All three tablets (two nirmatrelvir 150 mg tablets plus one ritonavir 100 mg tablet) should be taken together at approximately the same time each day 2
• Treatment can be taken with or without food 2

Critical Timing Considerations

• Initiate treatment as soon as possible after COVID-19 diagnosis and within 5 days of symptom onset 1, 3, 2
• Clinical trials administered Paxlovid within five days of symptom onset, and this timing window is essential for optimal effectiveness 1

Dose Modifications for Renal Impairment

While you asked about normal kidney function, it's critical to verify renal status before prescribing:

• Moderate renal impairment (eGFR 30-59 mL/min): Reduce to 150 mg nirmatrelvir with 100 mg ritonavir twice daily for all 5 days 1, 3, 2
• Severe renal impairment (eGFR <30 mL/min): 300 mg nirmatrelvir with 100 mg ritonavir once on day 1, then 150 mg nirmatrelvir with 100 mg ritonavir once daily on days 2-5 2
• For patients on hemodialysis, administer the dose after dialysis on dialysis days 2

Essential Pre-Prescribing Requirements

Before prescribing Paxlovid, you must check for drug-drug interactions using the Liverpool COVID-19 Drug Interaction Tool, as ritonavir is a potent CYP3A inhibitor that causes potentially severe, life-threatening interactions. 1, 3, 2

• Ritonavir causes drug interactions during active treatment and possibly for several days after completion 1
• Certain medications are absolutely contraindicated with Paxlovid due to risk of serious or life-threatening reactions 2
• Some concomitant medications may require dose adjustment, temporary interruption, or additional monitoring 2

Common Pitfalls to Avoid

• Do not use in severe hepatic impairment (Child-Pugh Class C) 2
• Do not prescribe without checking drug interactions first - this is the primary safety concern with Paxlovid 3, 2
• Do not extend treatment beyond 5 days - the evidence base and FDA authorization support only a 5-day course 1, 2
• Reassess renal function during treatment if clinical deterioration occurs, as COVID-19 itself can cause acute kidney injury 3

Expected Adverse Effects

• Dysgeusia (altered taste) and diarrhea are the most common adverse effects, occurring more frequently than with placebo 1
• These adverse effects did not lead to increased drug discontinuation rates in clinical trials 1