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Iobenguane I 123 use while Breastfeeding

Drugs containing Iobenguane I 123: AdreView

Medically reviewed by Last updated on Feb 18, 2019.

Iobenguane I 123 Levels and Effects while Breastfeeding

Summary of Use during Lactation

Information in this record refers to the use of iobenguane I 123 (I 123 meta-iodobenzylguanidine; I 123 MIBG) as a diagnostic agent. The United States Nuclear Regulatory Commission states that breastfeeding should be interrupted after administration of I 123 MIBG to a nursing mother. The duration of breastfeeding interruption depends on the dose administered (see table).[1][2] These values apparently refer to uncontaminated I 123. With contamination of I 124 or I 125, the interruption period is longer. The International Commission on Radiological Protection states that breastfeeding should be interrupted for more than 3 weeks following diagnostic use of sodium iodide I 123. This usually will result in permanent discontinuation of breastfeeding for this infant.[3] During the period of interruption, the breasts should be emptied regularly and completely. If the mother has expressed and saved milk prior to the examination, she can feed it to the infant during the period of nursing interruption.[4][5][6] The milk that is pumped by the mother during the time of breastfeeding interruption can either be discarded or stored refrigerated and given to the infant after 10 physical half-lives, or about 5.5 days, have elapsed.

Mothers concerned about the level of radioactivity in their milk could ask to have it tested at a nuclear medicine facility at their hospital. When the radioactivity is at a safe level she may resume breastfeeding. A method for measuring milk radioactivity and determining the time when a mother can safely resume breastfeeding has been published.[7]

Dose Duration of Interruption
400 MBq (10.8 mCi) 48 hours[2]
370 MBq (10 mCi) 24 hours[1]
150 MBq (4 mCi) 12 hours[1]

Drug Levels

I 123 is a gamma emitter with a photon energy of 159 keV and a physical half-life of 13.2 hours.[1] The effective half-life of I 123 MIBG averages 11.4 hours.[7]

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.


1. Howe DB, Beardsley M, Bakhsh S. Appendix U. Model procedure for release of patients or human research subjects administered radioactive materials. In, NUREG-1556. Consolidated guidance about materials licenses. Program-specific guidance about medical use licenses. Final report. U.S. Nuclear Regulatory Commission Office of Nuclear Material Safety and Safeguards. 2008;9, Rev. 2.

2. Bombardieri E, Giammarile F, Aktolun C et al. 131I/123I-metaiodobenzylguanidine (mIBG) scintigraphy: procedure guidelines for tumour imaging. Eur J Nucl Med Mol Imaging. 2010;37:2436-46. PMID: 20644928

3. Mattsson S, Johansson L, Leide Svegborn S et al. Radiation dose to patients from radiopharmaceuticals: A compendium of current information related to frequently used substances. Annex D. Recommendations on breast-feeding interruptions. Ann ICRP. 2015;44 (2 Suppl):319-21. PMID: 26069086

4. Mountford PJ, Coakley AJ. A review of the secretion of radioactivity in human breast milk: data, quantitative analysis and recommendations. Nucl Med Commun. 1989;10:15-27. PMID: 2645546

5. Early PJ, Sodee DB. Principles and practice of nuclear medicine. 2nd ed. St. Louis. Mosby-Year Book, Inc. 1995:1380-1.

6. Administration of Radioactive Substances Advisory Committee. Notes for guidance on the clinical administration of radiopharmaceuticals and use of sealed radioactive sources. 2006;25-7.

7. Stabin MG, Breitz HB. Breast milk excretion of radiopharmaceuticals: mechanisms, findings, and radiation dosimetry. J Nucl Med. 2000;41:863-73. PMID: 10809203

Iobenguane I 123 Identification

Substance Name

Iobenguane I 123

CAS Registry Number


Drug Class

Breast Feeding



Iodine Radioisotopes

Administrative Information

LactMed Record Number



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.

Further information

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