# Strontium-89 chloride

Source: https://nuclide.cc/drugs/sr-89-chloride/  
Nuclide record `sr-89-chloride` (Agent). Data CC BY-NC 4.0, attribute "Data from Nuclide (nuclide.cc)"; commercial use needs a licence.

## TL;DR

A radioactive form of strontium is injected into a vein. Because it behaves like calcium, it collects in the damaged, overactive bone around cancer that has spread to bone, and its radiation can relieve bone pain for months.

## Summary

Strontium-89 chloride (branded Metastron) is indicated for the relief of bone pain in patients with painful skeletal metastases, confirmed by a prior bone scan; it is not a treatment for the underlying cancer and does not relieve pain from soft tissue disease. The FDA label recommends a fixed dose of 148 MBq (4 mCi) by slow intravenous injection over one to two minutes, or a weight-based alternative of 1.5-2.2 MBq/kg (40-60 microCi/kg); repeat dosing is generally not recommended at intervals of less than 90 days and depends on haematological recovery.

Strontium-89 decays by beta emission with a physical half-life of 50.5 days; roughly two-thirds of excretion is urinary and one-third faecal in patients with bone metastases, with retention in metastatic lesions lasting much longer than the roughly 14-day turnover in normal bone. Pain relief typically begins 10-20 days after injection and can last three to six months; a transient pain flare in the first few days is common.

Metastron was originally marketed by Amersham/Zeneca and later GE Healthcare; the branded product was discontinued and the compound is now supplied generically (marketed as Strontium89). It sits alongside samarium-153 lexidronam and radium-223 dichloride as FDA/EMA-approved bone-palliation radiopharmaceuticals, though 89Sr and 153Sm are not tumour-type-restricted the way radium-223's label is limited to castration-resistant prostate cancer.

## Fields

- Kind: Agent
- Status: approved
- Last checked: 2026-09-22
- Also known as: Metastron; Strontium89; 89SrCl2
- Tags: bone pain palliation; beta emitter; calcium mimetic
- Brand: Metastron
- Modality: radioligand therapy
- Mechanism: Strontium-89 chloride is a calcium-mimetic, bone-seeking beta emitter given by intravenous injection. It behaves like calcium, clearing from blood and localising preferentially in bone mineral at sites of active osteogenesis, so blastic metastatic lesions accumulate far more strontium than normal bone and receive a higher local radiation dose that palliates pain.
- Approvals: US 1993: Relief of bone pain in patients with painful skeletal metastases (presence of bone metastases must be confirmed prior to therapy)
- Dosing: Slow intravenous injection (1-2 minutes); 148 MBq (4 mCi) fixed dose, or 1.5-2.2 MBq/kg (40-60 microCi/kg); repeat doses generally not within 90 days, based on response and haematological status

## Sources

- FDA label: Metastron (strontium-89 chloride injection): https://www.accessdata.fda.gov/drugsatfda_docs/label/2013/020134s012lbl.pdf
- SNMMI/EANM procedure guideline for palliative radionuclide bone therapies, 2023: https://tech.snmjournals.org/content/51/3/176

## Connected records

- drugs: [Radium-223 dichloride](https://nuclide.cc/drugs/radium-223/), [Samarium-153 lexidronam](https://nuclide.cc/drugs/samarium-153-lexidronam/)
- terms: [Bone metastases and skeletal-related events](https://nuclide.cc/terms/bone-metastases/)
- isotopes: [Radium-223](https://nuclide.cc/isotopes/ra-223/), [Samarium-153](https://nuclide.cc/isotopes/sm-153/), [Strontium-89](https://nuclide.cc/isotopes/sr-89/)

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