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Pegvisomant use while Breastfeeding

Medically reviewed by Last updated on May 14, 2023.

Drugs containing Pegvisomant: Somavert

Pegvisomant Levels and Effects while Breastfeeding

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

A woman with acromegaly was treated with lanreotide Autogel 120 mg monthly, cabergoline 2 mg weekly and pegvisomant 80 mg weekly. She breastfed (extent not stated) her infant and they were followed for 12 years. Her child had normal growth and development.[3]

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]
Popescu AD, Carsote M, Valea A, et al. Approach of acromegaly during pregnancy. Diagnostics (Basel). 2022;12:2669. [PMC free article: PMC9689290] [PubMed: 36359512]

Substance Identification

Substance Name


CAS Registry Number


Drug Class

Breast Feeding


Milk, Human

Human Growth Hormone Analogues and Derivatives

Growth Hormone Receptor Antagonists

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Further information

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