Paxlovid Dosing Frequency for COVID-19 Treatment
Paxlovid (nirmatrelvir/ritonavir) is taken twice daily for 5 days for the treatment of COVID-19.
Dosing Details
The standard dosing regimen for Paxlovid consists of:
- 300 mg nirmatrelvir (two 150 mg tablets) with 100 mg ritonavir (one 100 mg tablet)
- All 3 tablets taken together twice daily
- Administered at approximately the same time each day
- Course duration: 5 days
- Can be taken with or without food 1
Timing of Treatment
- Treatment should be initiated as soon as possible after diagnosis of COVID-19
- Must be started within 5 days of symptom onset for optimal effectiveness 1
- Earlier treatment (within the first few days of symptoms) is associated with better outcomes
Dose Adjustments
Renal Impairment
Moderate renal impairment (eGFR ≥30 to <60 mL/min):
- 150 mg nirmatrelvir (one tablet) with 100 mg ritonavir (one tablet) twice daily for 5 days
Severe renal impairment (eGFR <30 mL/min) including those requiring hemodialysis:
- Day 1: 300 mg nirmatrelvir (two tablets) with 100 mg ritonavir (one tablet) once
- Days 2-5: 150 mg nirmatrelvir (one tablet) with 100 mg ritonavir (one tablet) once daily 1
Hepatic Impairment
- Not recommended in patients with severe hepatic impairment (Child-Pugh Class C) 1
Clinical Considerations and Precautions
Drug Interactions
- Ritonavir is a strong CYP3A inhibitor that may lead to significant drug-drug interactions
- Prior to prescribing, clinicians must:
- Review all medications taken by the patient
- Determine if concomitant medications require dose adjustment, interruption, or additional monitoring 1
Common Adverse Effects
- Most common adverse reactions (incidence ≥1% and greater than placebo):
- Dysgeusia (altered taste)
- Diarrhea 1
Effectiveness
- Paxlovid has demonstrated a 39% reduction in risk of hospitalization and 61% reduction in risk of death in real-world effectiveness studies 2
- Particularly beneficial for older adults (65+ years) and those with risk factors for severe COVID-19 2
Pitfalls and Caveats
Drug Interactions: Ritonavir component causes numerous drug-drug interactions that require careful medication review before prescribing.
Timing Window: Must be started within 5 days of symptom onset. However, recent evidence suggests it may still be effective when started within 10 days of symptom onset in patients with high viral load 3.
COVID-19 Rebound: Some patients may experience recurrence of symptoms 2-8 days after completing the treatment course, sometimes with positive test results after previously testing negative 4.
Adherence: The twice-daily regimen requires strict adherence for full effectiveness. Patients should be counseled on the importance of completing the full 5-day course.
Pregnancy: Limited data exists on use during pregnancy as pregnant women were excluded from major clinical trials 5.
By following these dosing recommendations and considering the potential drug interactions and contraindications, Paxlovid can effectively reduce the risk of hospitalization and death in patients with COVID-19.