C1 Esterase Inhibitor

Drug Levels and Effects:

Summary of Use during Lactation:

C1 esterase inhibitor [human] is a serine proteinase inhibitor derived fromhumanplasma that is used in treating hereditary angioedema. Breastmilk levels of C1 esterase inhibitor have not been measured after exogenous administration in humans. Because of its large molecular weight, amounts in milk are expected to be small. Any C1 esterase inhibitor in breastmilk is probably destroyed in the infant's gastrointestinal tract and not absorbed, except perhaps in neonates. An international consensus panel states thathumanplasma-derived C1 esterase inhibitor is considered to be the therapy of choice for both treatment and prophylaxis of maternal hereditary angioedema during lactation.[1]

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:

Three patients with hereditary angioedema received C1 esterase inhibitor concentrate on 12 occasions to relieve abdominal edematous episodes during breastfeeding. No adverse reactions were reported.[2]

In a case series spanning 12 years, 21 mothers with hereditary angioedema breastfed their infants for a median duration of 4.8 months (range 1 to 34 months) while receiving C1 esterase inhibitor concentrate as needed. No side effects occurred tin the breastfed infants.[3]

Possible Effects on Lactation:

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


1. Caballero T, Farkas H, Bouillet L et al. International consensus and practical guidelines on the gynecologic and obstetric management of female patients with hereditary angioedema caused by C1 inhibitor deficiency. J Allergy Clin Immunol. 2012;129:308-20. PMID:22197274
2. Czaller I, Visy B, Csuka D et al. The natural history of hereditary angioedema and the impact of treatment withhumanC1-inhibitor concentrate during pregnancy: a long-term survey. Eur J Obstet Gynecol Reprod Biol. 2010;152:44-9. PMID:20541309
3. Martinez-Saguer I, Rusicke E, Aygoren-Pursun E et al. Characterization of acute hereditary angioedema attacks during pregnancy and breast-feeding and their treatment with C1 inhibitor concentrate. Am J Obstet Gynecol. 2010;203:131.e1-7. PMID:20471627

Substance Identification:

Substance Name:

C1 Esterase Inhibitor

CAS Registry Number:


Drug Class:

  • Complement C1 Inactivator Proteins

  • Administrative Information:

    LactMed Record Number:


    Last Revision Date:

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