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Intussusception — USMLE Step 3 MCQ

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HardPediatrics (well-child, chronic management)IntussusceptionUSMLE Step 3

A high-risk outpatient presents on day 2 of COVID-19 symptoms. Estimated GFR is 24 mL/min, medication-interaction review is complete, and nirmatrelvir/ritonavir is selected. Which FDA-labeled regimen is correct?

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Correct answer: E — Day 1: nirmatrelvir 300 mg plus ritonavir 100 mg once; days 2–5: nirmatrelvir 150 mg plus ritonavir 100 mg once daily

The best answer is “Day 1: nirmatrelvir 300 mg plus ritonavir 100 mg once; days 2–5: nirmatrelvir 150 mg plus ritonavir 100 mg once daily”. An eGFR below 30 mL/min uses the severe-renal-impairment schedule, not the standard or moderate-impairment schedule. Ritonavir remains part of every dose because it supplies the pharmacokinetic boosting required for effective nirmatrelvir exposure. For severe renal impairment with eGFR below 30 mL/min, the FDA regimen is nirmatrelvir 300 mg plus ritonavir 100 mg once on day 1, followed by nirmatrelvir 150 mg plus ritonavir 100 mg once daily on days 2–5. The alternatives use a different threshold, timing, population, or intervention and therefore do not match the clinical facts presented.

Reference: FDA: PAXLOVID Prescribing Information: https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/217188s008lbl.pdf