Technetium Tc 99m Exametazime and Breastfeeding

Summary of use during lactation

Information in this record refers to the use of technetium Tc 99m exametazime (Tc 99m-hexamethylpropyleneamine oxime; Tc 99m HPAO; Tc 99m HMPAO) as a diagnostic agent. A US Nuclear Regulatory Commission subcommittee has recommended that nursing be discontinued for 24 hours after administration of all technetium Tc 99m diagnostic products to simplify guidance recommendations, although this time interval may be longer than necessary.[1] Other experts state that breastfeeding need not be interrupted after administration of technetium Tc 99m exametazime in doses up to 500 MBq (15 mCi) to a nursing mother.[2-4] However, to follow the principle of keeping exposure "as low as reasonably achievable", some experts recommend nursing the infant just before administration of the radiopharmaceutical and interrupting breastfeeding for 3 to 6 hours after the dose, then expressing the milk completely once and discarding it. 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.[4-6] Mothers need not refrain from close contact with their infants after usual clinical doses.[2] For white blood cells labeled with technetium Tc 99m exametazime 180 to 400 MBq, the International Atomic Energy Agency recommends that breastfeeding should be interrupted for 12 hours.[6] 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] For nursing mothers who work with Tc 99m substances in their workplace, there is no need to take any precautions other than those appropriate for general radiation protection.[8]

Drug levels in milk and infant serum

Tc 99m is a gamma emitter with a principal photon energy of 140 keV and a physical half-life of 6.04 hours.[1] The effective half-life of technetium Tc 99m exametazime leukocytes is 7.5 hours, and 0.11% of the administered dose appears in breastmilk.[9]

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.

References

1. Dilsizian V, Metter D, Palestro C, Zanzonico P. Advisory Committee on Medical Uses of Isotopes (ACMUI) Sub-Committee on Nursing Mother Guidelines for the Medical Administration of Radioactive Material. Final report submitted: January 31, 2019. 2019. https://www.nrc.gov/docs/ML1903/ML19038A498.pdf
2. Mountford PJ, O'Doherty MJ. Exposure of critical groups to nuclear medicine patients. Appl Radiat Isot 1999;50:89-111.10028630 PubMed
3. Marshall DS, Newberry NR, Ryan PJ. Measurement of the secretion of technetium-99m hexamethylpropylene amine oxime into breast milk. Eur J Nucl Med 1996;23:1634-5.8929318 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. Mountford PJ, Coakley AJ. A review of the secretion of radioactivity in human breast milk: Data, quantitative analysis and recommendations. Nucl Med Commun 1989;10:15-27.2645546 PubMed
6. International Atomic Energy Agency. Radiation Protection and Safety in Medical Uses of Ionizing Radiation, IAEA Safety Standards Series No. SSG-46, IAEA, Vienna. 2018. https://www.iaea.org/publications/11102/radiation-protection-and-safety-in-medical-uses-of-ionizing-radiation
7. Stabin MG, Breitz HB. Breast milk excretion of radiopharmaceuticals: Mechanisms, findings, and radiation dosimetry. J Nucl Med 2000;41:863-73.10809203 PubMed
8. Almén A, Mattsson S. Radiological protection of foetuses and breast-fed children of occupationally exposed women in nuclear medicine - Challenges for hospitals. Phys Med 2017;43:172-7.28882410 PubMed
9. Leide-Svegborn S, Ahlgren L, Johansson L, Mattsson S. Excretion of radionuclides in human breast milk after nuclear medicine examinations. Biokinetic and dosimetric data and recommendations on breastfeeding interruption. Eur J Nucl Med Mol Imaging 2016;43:808-21.26732471 PubMed