The Basics
What is Thallous Chloride Tl 201?
Used to help diagnose heart disease used in certain procedures called planar scintigraphy or single-photon emission computed tomography (SPECT).
Brand names for Thallous Chloride Tl 201
Thallous Chloride Tl-201 Injection
How Thallous Chloride Tl 201 is classified
Radiopharmaceuticals, Thallium Radioisotopes, Diagnostic Agents
Thallous Chloride Tl 201 During Pregnancy
Thallous Chloride Tl 201 pregnancy category
Category CNote that the FDA has deprecated the use of pregnancy categories, so for some medications, this information isn’t available. We still think it’s useful to list historical info, however, given what a common proxy this has been in the past.
What we know about taking Thallous Chloride Tl 201 while pregnant
Animal reproductive studies have not been conducted with Thallous Chloride Tl-201. It is also not known whether Thallous Chloride Tl-201 can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity. Thallous Chloride Tl-201 should be given to a pregnant woman only if clearly needed.
Taking Thallous Chloride Tl 201 While Breastfeeding
What are recommendations for lactation if you're taking Thallous Chloride Tl 201?
Information in this record refers to the use of thallous chloride Tl 201 as a diagnostic agent. Most experts recommend a period of breastfeeding interruption after maternal thallous chloride Tl 201, although some disagreement exists on the exact duration, probably because of the long physical half-life of the radioisotope and variable elimination of the drug from the body. One older paper recommends a 2-week discontinuation period after a dose of 110 MBq.[1] 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.[2][3][4] The milk that is pumped by the mother during the time of breastfeeding interruption can either be discarded or stored frozen and given to the infant after 10 physical half-lives, or about 30 days, have elapsed. After doses greater than 150 MBq, consideration of temporarily limiting close contact between the mother and infant.[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]
| Dose | Duration of Interruption |
|---|---|
| 100 MBq (3 mCi) | 4 days[5][6] |
| 80 MBq (2.4 mCi) | 10 hours[4] |
Maternal / infant drug levels
Information in this record refers to the use of thallous chloride Tl 201 as a diagnostic agent. Most experts recommend a period of breastfeeding interruption after maternal thallous chloride Tl 201, although some disagreement exists on the exact duration, probably because of the long physical half-life of the radioisotope and variable elimination of the drug from the body. One older paper recommends a 2-week discontinuation period after a dose of 110 MBq.[1] 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.[2][3][4] The milk that is pumped by the mother during the time of breastfeeding interruption can either be discarded or stored frozen and given to the infant after 10 physical half-lives, or about 30 days, have elapsed. After doses greater than 150 MBq, consideration of temporarily limiting close contact between the mother and infant.[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]
| Dose | Duration of Interruption |
|---|---|
| 100 MBq (3 mCi) | 4 days[5][6] |
| 80 MBq (2.4 mCi) | 10 hours[4] |
Possible effects of Thallous Chloride Tl 201 on milk supply
Relevant published information was not found as of the revision date.
Possible alternatives to Thallous Chloride Tl 201
Technetium Tc 99m Sestamibi, Technetium Tc 99m Tetrofosmin.
List of References
Lactation sources: Drugs and Lactation Database (LactMed) [Internet]. Bethesda (MD): National Library of Medicine (US); 2006-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK501922/1. 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. http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1556/v9/r2/
2. 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
3. Early PJ, Sodee DB. Principles and practice of nuclear medicine. 2nd ed. St. Louis. Mosby-Year Book, Inc.1995:1380-1.
4. National Radiation Protection Board (UK). Administration of radioactive substances advisory committee. Notes for guidance on the clinical administration of radiopharmaceuticals and use of sealed radioactive sources. 2019. https://assets.publishing.service.gov.uk/government/…/file/…/ARSAC_NfG_2019.pdf
5. Stabin MG, Breitz HB. Breast milk excretion of radiopharmaceuticals: mechanisms, findings, and radiation dosimetry. J Nucl Med. 2000;41:863-73. PMID: 10809203
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
Disclaimer: This material is provided for educational purposes only and is not intended for medical advice, diagnosis, or treatment. Consult your healthcare provider with any questions.
