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Drugs and Lactation Database (LactMed®) [Internet]. Bethesda (MD): National Institute of Child Health and Human Development; 2006-.
CASRN: 2628280-40-8
Drug Levels and Effects
Summary of Use during Lactation
Nirmatrelvir is given in combination with ritonavir, which enhances its bioavailability. Minimal information is available on the use of nirmatrelvir during breastfeeding. Ritonavir is excreted into milk in measurable concentrations and low levels can be found in the blood of some breastfed infants. No reports of adverse reactions in breastfed infants have been reported. For more information, refer to the LactMed record on ritonavir. Because of the poor oral bioavailability of nirmatrelvir and small amounts of ritonavir in milk, this combination is unlikely to adversely affect the nursing infant.[1,2] Breastfeeding is not contraindicated during nirmatrelvir-ritonavir therapy in the US and Canada, but cessation of breastfeeding during its use is recommended in Europe.[1] Until more data are available it should only be used with careful infant monitoring for adverse effects.
Drug Levels
Maternal Levels. Relevant published information was not found as of the revision date.
Infant Levels. Relevant published information was not found as of the revision date.
Effects in Breastfed Infants
In a cross-sectional study of women who had COVID-19 and received nirmatrelvir in combination ritonavir, two women breastfed their infants. No adverse effects were reported in the infants.[3]
Effects on Lactation and Breastmilk
Relevant published information was not found as of the revision date.
Alternate Drugs to Consider
References
- 1.
- Chourasia P, Maringanti BS, Edwards-Fligner M, et al. Paxlovid (nirmatrelvir and ritonavir) use in pregnant and lactating woman: Current evidence and practice guidelines-a scoping review. Vaccines (Basel). 2023;11:107. [PMC free article: PMC9866309] [PubMed: 36679952]
- 2.
- Anderson PO. COVID-19 drugs and breastfeeding update. Breastfeed Med. 2022;17:377–9. [PubMed: 35384717]
- 3.
- Lin CY, Cassidy AG, Li L, et al. Nirmatrelvir-ritonavir (Paxlovid) for mild coronavirus disease 2019 (COVID-19) in pregnancy and lactation. Obstet Gynecol. 2023;141:957–60. [PMC free article: PMC10147578] [PubMed: 36928334]
Substance Identification
Substance Name
Nirmatrelvir
CAS Registry Number
2628280-40-8
Disclaimer: Information presented in this database is not meant as a substitute for professional judgment. You should consult your healthcare provider for breastfeeding advice related to your particular situation. The U.S. government does not warrant or assume any liability or responsibility for the accuracy or completeness of the information on this Site.
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- Paxlovid mouth likely is mediated by activation of the TAS2R1 bitter receptor by nirmatrelvir.[Biochem Biophys Res Commun. 2023]Paxlovid mouth likely is mediated by activation of the TAS2R1 bitter receptor by nirmatrelvir.Caronia L, Xi R, Margolskee RF, Jiang P. Biochem Biophys Res Commun. 2023 Nov 19; 682:138-140. Epub 2023 Oct 2.
- Review Nirmatrelvir combined with ritonavir for preventing and treating COVID-19.[Cochrane Database Syst Rev. 2023]Review Nirmatrelvir combined with ritonavir for preventing and treating COVID-19.Reis S, Metzendorf MI, Kuehn R, Popp M, Gagyor I, Kranke P, Meybohm P, Skoetz N, Weibel S. Cochrane Database Syst Rev. 2023 Nov 30; 11(11):CD015395. Epub 2023 Nov 30.
- Nirmatrelvir - Drugs and Lactation Database (LactMed®)Nirmatrelvir - Drugs and Lactation Database (LactMed®)
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