Small study tests COVID pill levels in breast milk
NCT ID NCT05441215
First seen Jun 24, 2026 · Last updated Jun 27, 2026 · Updated 1 time
Summary
This completed Phase 1 study looked at how much of the COVID-19 treatment nirmatrelvir/ritonavir (Paxlovid) gets into breast milk. Eight healthy breastfeeding women took the drug by mouth three times over two days. Researchers collected breast milk samples to measure drug levels, aiming to provide safety information for nursing mothers.
What this could mean
Our plain-language read of the trial. This is informational only — not medical advice or a prediction.
- Active substance
- nirmatrelvir/ritonavir (Paxlovid)
- What this could lead to
- If successful, this study could help doctors understand whether nirmatrelvir/ritonavir is safe for breastfeeding women and their infants.
- What could go wrong
- This is a very small, early-phase study with only 8 participants. It measures drug levels in breast milk, not safety or effectiveness in treating illness.
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Conditions
The condition(s) this trial relates to.
As listed by the trial registrant
The condition terms exactly as the trial's registrant entered them.
Contacts and locations
Locations
-
Pfizer Clinical Research Unit - Brussels
Brussels, Bruxelles-capitale, Région de, B-1070, Belgium
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