# Samarium-153

Source: https://nuclide.cc/isotopes/sm-153/  
Nuclide record `sm-153` (Isotope). Data CC BY-NC 4.0, attribute "Data from Nuclide (nuclide.cc)"; commercial use needs a licence.

## TL;DR

A radioactive metal, given as an injection, that homes in on the actively growing edges of bone and gives off radiation there. It is used to ease pain from cancer that has spread to bone.

## Summary

Samarium-153 lexidronam (Quadramet, 153Sm-EDTMP) delivers 153Sm chelated to a bone-seeking phosphonate that concentrates roughly five-fold more in osteoblastic lesions than in normal bone. It decays with a physical half-life of 46.3 hours (1.93 days) by emission of three principal beta-particle energies (maxima around 640, 710 and 810 keV; mean beta energy about 233 keV) plus a 103 keV gamma photon (about 28-29% abundance) that permits scintigraphic imaging of biodistribution.

The beta particles have an average range in soft tissue of roughly 0.5-0.8 mm and a maximum of about 3 mm (about 1.7 mm in bone), similar in scale to other bone-palliation radiopharmaceuticals but with a much shorter half-life than strontium-89, giving faster onset and clearance.

153Sm is produced in high yield and purity by neutron irradiation of isotopically enriched samarium-152 oxide (152Sm2O3) in a reactor, 152Sm(n,γ)153Sm; this is a routine, widely available reactor product and not considered supply-constrained, though Quadramet's US manufacturer has changed hands and availability has fluctuated commercially.

## Fields

- Kind: Isotope
- Status: approved
- Last checked: 2026-09-22
- Also known as: 153Sm; Sm-153
- Tags: therapy; beta emitter; gamma emitter; bone-seeking

## Sources

- FDA/manufacturer label: Quadramet (samarium Sm-153 lexidronam) prescribing information: https://www.drugs.com/pro/quadramet.html
- EMA: Quadramet EPAR product information: https://www.ema.europa.eu/en/documents/product-information/quadramet-epar-product-information_en.pdf
- FDA: comparative physical properties of bone-palliation radiopharmaceuticals (Xofigo NDA review): https://www.accessdata.fda.gov/drugsatfda_docs/nda/2013/203971Orig1s000RiskR.pdf

## Connected records

- drugs: [Samarium-153 lexidronam](https://nuclide.cc/drugs/samarium-153-lexidronam/), [Strontium-89 chloride](https://nuclide.cc/drugs/sr-89-chloride/)
- terms: [Bone metastases and skeletal-related events](https://nuclide.cc/terms/bone-metastases/), [Flare phenomenon](https://nuclide.cc/terms/flare-phenomenon/)
- isotopes: [Strontium-89](https://nuclide.cc/isotopes/sr-89/)
- indications: [Bone pain palliation from osteoblastic metastases](https://nuclide.cc/indications/bone-pain-palliation/), [Osteosarcoma](https://nuclide.cc/indications/osteosarcoma/), [Prostate cancer](https://nuclide.cc/indications/prostate/)
- companies: [Curium](https://nuclide.cc/companies/curium/), [Lantheus](https://nuclide.cc/companies/lantheus/)
- fronts: [Bone-targeted radiopharmaceuticals](https://nuclide.cc/fronts/f-bone-targeted/)
- targets: [Bone mineral (hydroxyapatite)](https://nuclide.cc/targets/bone-hydroxyapatite/)

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