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Drugs and Lactation Database (LactMed) [Internet]. Bethesda (MD): National Library of Medicine (US); 2006-.

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Drugs and Lactation Database (LactMed) [Internet].

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Last Revision: January 18, 2022.

Estimated reading time: 1 minute

CASRN: 218620-50-9

Drug Levels and Effects

Summary of Use during Lactation

Limited data indicate that pegvisomant is poorly excreted into breastmilk. Because pegvisomant is not orally absorbed, it is unlikely to adversely affect the breastfed infant. Polyethylene glycol is not excreted into breastmilk.[1]

Drug Levels

A woman was being treated during pregnancy for acromegaly with subcutaneous pegvisomant at a dosage that was progressively escalated from 15 mg to 25 mg daily during the course of pregnancy, and presumably postpartum. At an unreported time postpartum, pegvisomant was not detectable (<50 mcg/L) in breastmilk. The patient's breastmilk growth hormone concentration was 0.6 mcg/L compared to <0.1 mcg/L in 3 breastmilk samples from normal healthy mothers.[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]
Brian SR, Bidlingmaier M, Wajnrajch MP, et al. Treatment of acromegaly with pegvisomant during pregnancy: Maternal and fetal effects. J Clin Endocrinol Metab. 2007;92:3374–7. [PubMed: 17595256]

Substance Identification

Substance Name


CAS Registry Number


Drug Class

Breast Feeding


Human Growth Hormone Analogues and Derivatives

Growth Hormone Receptor Antagonists

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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