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Pegvaliase use while Breastfeeding

Medically reviewed by Last updated on Aug 29, 2022.

Drugs containing Pegvaliase: Palynziq

Pegvaliase Levels and Effects while Breastfeeding

Summary of Use during Lactation

No information is available on the use of pegvaliase during breastfeeding, but amounts in milk appear to be trivial. Absorption of the drug by the infant from breastmilk is unlikely because it is a polypeptide that is probably destroyed in the infant's gastrointestinal tract. Polyethylene glycol is not excreted into breastmilk.[1] Pegvaliase may decrease the phenylalanine content of breastmilk. The manufacturer recommends monitoring blood phenylalanine concentrations in breastfeeding women treated with pegvaliase.

Drug Levels

Maternal Levels. A woman with phenylketonuria stopped her pegvaliase during pregnancy and for 7 months while breastfeeding her infant. After weaning, she restarted pegvaliase and pumped breastmilk samples for analysis while taking a dose of 20 mg daily. The activity of phenylalanine ammonia lyase (the active portion of pegvaliase) was equal to background levels found in blank breastmilk and TRIS buffer solution.[2]

Infant Levels. Relevant published information was not found as of the revision date.

Effects in Breastfed Infants

Relevant published information was not found as of the revision date.

Effects on Lactation and Breastmilk

Relevant published information was not found as of the revision date.


Clowse ME, Förger F, Hwang C, et al. Minimal to no transfer of certolizumab pegol into breast milk: Results from CRADLE, a prospective, postmarketing, multicentre, pharmacokinetic study. Ann Rheum Dis. 2017;76:1890–6. [PMC free article: PMC5705850] [PubMed: 28814432]
Rohr F, Kritzer A, Harding CO, et al. Discontinuation of pegvaliase therapy during maternal PKU pregnancy and postnatal breastfeeding: A case report. Mol Genet Metab Rep. 2020;22:100555. [PMC free article: PMC6957825] [PubMed: 31956506]

Substance Identification

Substance Name


CAS Registry Number


Drug Class

Breast Feeding




Recombinant Proteins

Phenylalanine Ammonia Lyase,

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Further information

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