Paxlovid Dosing for Pediatric Patients
Paxlovid (nirmatrelvir/ritonavir) is authorized for children ≥12 years of age weighing ≥40 kg at the standard adult dose of 300 mg nirmatrelvir/100 mg ritonavir twice daily for 5 days. 1, 2
Age and Weight Requirements
- Minimum age: 12 years 1
- Minimum weight: 40 kg (88 lbs) 1, 2
- Children <12 years or <40 kg: Paxlovid is NOT FDA-authorized for this population 1
Standard Dosing Regimen
- Dose: Nirmatrelvir 300 mg with ritonavir 100 mg 2
- Frequency: Twice daily 2
- Duration: 5 days 1, 2
- Timing: Must be initiated within 5 days of symptom onset 1, 2
Dose Adjustments
Renal Impairment
- Moderate renal impairment (eGFR 30-59 mL/min): Reduce to nirmatrelvir 150 mg/ritonavir 100 mg twice daily for 5 days 2
- Severe renal impairment (eGFR <30 mL/min): Paxlovid is not recommended 2
No Adjustment Needed
- Age alone: No dose reduction based solely on pediatric age if weight ≥40 kg 2
- Hepatic impairment: No specific dose adjustment mentioned in available evidence for mild-to-moderate hepatic dysfunction 2
Critical Safety Considerations
Drug Interactions
Ritonavir is a potent CYP3A4 inhibitor, creating significant drug-drug interaction risks. 3, 2 This is particularly problematic in pediatric patients on:
- Immunosuppressants: Tacrolimus should be discontinued or given as a microdose; cyclosporine reduced to 20% of baseline dose 3
- Other CYP3A4 substrates: Review all concomitant medications before prescribing 3, 2
Limited Pediatric Data
The evidence base for Paxlovid in children is extremely limited:
- Small case series show feasibility in children aged 6-14 years with underlying conditions 4, 5
- One study reported viral clearance in 4-11 days with minimal adverse effects (transient diarrhea, elevated liver enzymes) 4
- Another series of 3 children (ages 12-17) showed symptom resolution in 1-2 days and negative PCR in 2-4 days 5
However, these off-label uses in younger/lighter children should only be considered in exceptional circumstances with careful risk-benefit assessment, as FDA authorization explicitly requires age ≥12 years and weight ≥40 kg. 1
Monitoring During Treatment
- Liver enzymes: Monitor if clinically indicated, as transient elevations have been reported 4
- Gastrointestinal symptoms: Diarrhea may occur 4
- Skin reactions: Rash reported in one pediatric case, resolved after discontinuation 5
Common Pitfalls to Avoid
- Do not use in children <12 years or <40 kg unless in exceptional research/compassionate use settings, as this is outside FDA authorization 1
- Do not overlook drug interactions: The ritonavir component requires comprehensive medication review before prescribing 3, 2
- Do not delay initiation: Must start within 5 days of symptom onset for efficacy 1, 2
- Do not use in severe renal impairment: Contraindicated when eGFR <30 mL/min 2