Iothalamate Sodium I 125 and Breastfeeding

Summary of use during lactation

Information in this record refers to the use of iothalamate sodium I 125 as a kidney function diagnostic agent. No information is available on the use of iothalamate sodium I 125 during breastfeeding. However, the biologic half-life of iothalamate after intravenous administration is 1.5 hours with normal kidney function, so the drug will be almost completely eliminated from the body in 8 hours. This time may be longer in patients with impaired kidney function and in patients who receive the drug by subcutaneous injection.[1] 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.[2-4] 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 background levels, they may safely resume breastfeeding. A method for measuring milk radioactivity and determining the time when a mother can safely resume breastfeeding has been published.[5]

Drug levels in milk and infant serum

I 125 is a low-energy pure gamma emitter with a physical half-life of 59.4 days.[6]

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.

Alternative drugs to consider

Iodohippurate Sodium I 125

References

1. Turkel C, Fox A. Hints for successful use of subcutaneous Glofil-125. Nephron 1998;78:230.9496747 PubMed
2. Mountford P, Coakley A. A review of the secretion of radioactivity in human breast milk: Data, quantitative analysis and recommendations. Nucl Med Commun 1989;10:15-27.2645546 PubMed
3. Chen M, Coakley F, Kaimal A, et al. Guidelines for computed tomography and magnetic resonance imaging use during pregnancy and lactation. Obstet Gynecol 2008;112:333-40.18669732 PubMed
4. ARSAC notes for guidance: Good clinical practice in nuclear medicine. Notes for guidance on the clinical administration of radiopharmaceuticals and use of sealed radioactive sources. 2020. https://www.gov.uk/government/publications/arsac-notes-for-guidance
5. Stabin M, Breitz H. Breast milk excretion of radiopharmaceuticals: Mechanisms, findings, and radiation dosimetry. J Nucl Med 2000;41:863-73.10809203 PubMed
6. 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. ICRP Publication 128. Annex D. Recommendations on breast-feeding interruptions. Ann ICRP 2015;44 (2 Suppl):319-21.