{"entity":{"id":"ra-223","kind":"isotope","name":"Radium-223","aka":["223Ra","Ra-223"],"tldr":"A radioactive form of the mineral radium that behaves like calcium and settles into bone. It gives off very short-range, high-energy particles that damage cancer growing in bone while barely reaching the healthy marrow next to it.","summary":"Radium-223 dichloride (Xofigo) is a calcium mimetic that concentrates in areas of increased bone turnover, such as osteoblastic bone metastases. It decays through a six-stage chain to stable lead-207, emitting predominantly alpha particles (95.3% of emitted energy), with small beta (3.6%) and gamma (1.1%) contributions from itself and its short-lived daughters (polonium-215, lead-211, bismuth-211, thallium-207).\n\nThe alpha range is under 100 micrometres in tissue (maximum about 6.2 cm in air), so the dose is deposited within roughly the width of a few cells of the bone surface, largely sparing the adjacent marrow. It was the first alpha-emitting radiopharmaceutical to gain FDA and EMA approval, on the strength of the ALSYMPCA trial's overall-survival benefit in metastatic castration-resistant prostate cancer with symptomatic bone metastases and no known visceral disease.\n\nRa-223 is obtained from a generator chain rooted in actinium-227 (itself made by neutron irradiation of radium-226 in a reactor); Ac-227 beta-decays to thorium-227, which alpha-decays to Ra-223. Commercial-scale 223Ra is available from Bayer's own supply chain and, more broadly, ORNL, PNNL and Rosatom hold production capability; a 2025 review (the PSI-led 'Alpha Atlas') judged that, unlike most other alpha emitters, 223Ra supply is adequate to global demand and no near-term shortage is expected.","status":"approved","asOf":"2026-09-22","links":[{"label":"FDA label: Xofigo (radium Ra 223 dichloride)","url":"https://www.accessdata.fda.gov/drugsatfda_docs/label/2013/203971lbl.pdf"},{"label":"Radium-223 mechanism of action (Nature Reviews Urology, 2019)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC7515774/"},{"label":"Production and supply of alpha particle emitting radionuclides for TAT (JNM, 2021)","url":"https://jnm.snmjournals.org/content/jnumed/early/2021/07/22/jnumed.120.261016.full.pdf"},{"label":"Alpha Atlas: mapping global production of alpha-emitting radionuclides for TAT (PSI, 2025)","url":"https://www.dora.lib4ri.ch/psi/islandora/object/psi:68199/datastream/PDF/Tosato-2025-Alpha_Atlas-(published_version).pdf"}],"tags":["therapy","alpha emitter","bone-seeking"],"related":["radium-223","alsympca","paper-alsympca-radium-223-nejm-2013","bone-metastases","th-227","targeted-alpha-therapy"],"indications":[],"sections":[],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"223Ra","element":"Radium","massNumber":223,"halfLife":"11.4 days","emissions":["α (95.3% of emitted energy, range 5-7.5 MeV)","β− (3.6%, average 0.445 and 0.492 MeV)","γ (1.1%, 0.01-1.27 MeV range)"],"emissionClass":"alpha","use":"therapy","tissueRange":"Under 100 micrometres in tissue; up to 6.2 cm in air","production":"Generator chain from reactor-made actinium-227 (226Ra(n,γ)227Ra → β− → 227Ac), which beta-decays to 227Th, which alpha-decays to 223Ra.","supply":"adequate","supplyNote":"223Ra is judged adequately supplied worldwide; Bayer is the primary commercial supplier, with ORNL, PNNL and Rosatom also holding production capability for 223Ra and its 227Th parent.","chelators":[],"pairedWith":[],"since":2013},"route":"/isotopes/ra-223/","neighbours":{"drug":[{"id":"radium-223","kind":"drug","name":"Radium-223 dichloride","route":"/drugs/radium-223/"},{"id":"samarium-153-lexidronam","kind":"drug","name":"Samarium-153 lexidronam","route":"/drugs/samarium-153-lexidronam/"},{"id":"sr-89-chloride","kind":"drug","name":"Strontium-89 chloride","route":"/drugs/sr-89-chloride/"}],"trial":[{"id":"alsympca","kind":"trial","name":"ALSYMPCA","route":"/trials/alsympca/"}],"paper":[{"id":"paper-alsympca-radium-223-nejm-2013","kind":"paper","name":"ALSYMPCA: alpha emitter radium-223 and survival in metastatic prostate cancer with bone metastases","route":"/key-papers/paper-alsympca-radium-223-nejm-2013/"},{"id":"paper-sgouros-tat-review-nat-rev-2020","kind":"paper","name":"Radiopharmaceutical therapy in cancer: clinical advances and challenges","route":"/key-papers/paper-sgouros-tat-review-nat-rev-2020/"}],"term":[{"id":"alpha-vs-beta","kind":"term","name":"Alpha vs beta emitters","route":"/terms/alpha-vs-beta/"},{"id":"bone-metastases","kind":"term","name":"Bone metastases and skeletal-related events","route":"/terms/bone-metastases/"},{"id":"flare-phenomenon","kind":"term","name":"Flare phenomenon","route":"/terms/flare-phenomenon/"},{"id":"mcrpc-mhspc","kind":"term","name":"mCRPC and mHSPC (castration-resistant vs hormone-sensitive prostate cancer)","route":"/terms/mcrpc-mhspc/"}],"isotope":[{"id":"sr-89","kind":"isotope","name":"Strontium-89","route":"/isotopes/sr-89/"},{"id":"th-227","kind":"isotope","name":"Thorium-227","route":"/isotopes/th-227/"}],"technology":[{"id":"macropa-chelation","kind":"technology","name":"Macropa chelation","route":"/technologies/macropa-chelation/"},{"id":"targeted-alpha-therapy","kind":"technology","name":"Targeted alpha therapy","route":"/technologies/targeted-alpha-therapy/"}],"indication":[{"id":"bone-pain-palliation","kind":"indication","name":"Bone pain palliation from osteoblastic metastases","route":"/indications/bone-pain-palliation/"},{"id":"prostate-mcrpc","kind":"indication","name":"Metastatic castration-resistant prostate cancer","route":"/indications/prostate-mcrpc/"},{"id":"osteosarcoma","kind":"indication","name":"Osteosarcoma","route":"/indications/osteosarcoma/"},{"id":"prostate","kind":"indication","name":"Prostate cancer","route":"/indications/prostate/"}],"company":[{"id":"bayer","kind":"company","name":"Bayer","route":"/companies/bayer/"}],"institution":[{"id":"oslo-radium-hospital","kind":"institution","name":"Oslo University Hospital, The Norwegian Radium Hospital","route":"/institutions/oslo-radium-hospital/"}],"roadmap":[{"id":"alpha-therapy-roadmap","kind":"roadmap","name":"Alpha-emitter roadmap: radium-223 → 225Ac-PSMA-617 → a phase 3 pipeline","route":"/roadmaps/alpha-therapy-roadmap/"},{"id":"radiopharma-roadmap","kind":"roadmap","name":"Radiopharmaceutical roadmap: iodine → lutetium → actinium","route":"/roadmaps/radiopharma-roadmap/"}],"collection":[{"id":"prostate-cancer-foundation","kind":"collection","name":"Prostate Cancer Foundation (PCF)","route":"/collections/prostate-cancer-foundation/"}],"person":[{"id":"oliver-sartor","kind":"person","name":"A. Oliver Sartor","route":"/people/oliver-sartor/"},{"id":"chris-parker","kind":"person","name":"Chris C. Parker","route":"/people/chris-parker/"},{"id":"karim-fizazi","kind":"person","name":"Karim Fizazi","route":"/people/karim-fizazi/"}],"section":[{"id":"f-bone-targeted","kind":"section","name":"Bone-targeted radiopharmaceuticals","route":"/fronts/f-bone-targeted/"},{"id":"f-alpha-therapy","kind":"section","name":"Targeted alpha therapy","route":"/fronts/f-alpha-therapy/"}],"pairing":[{"id":"radium223-abiraterone-caution","kind":"pairing","name":"Radium-223 with abiraterone: a caution, not a combination","route":"/pairings/radium223-abiraterone-caution/"}],"target":[{"id":"bone-hydroxyapatite","kind":"target","name":"Bone mineral (hydroxyapatite)","route":"/targets/bone-hydroxyapatite/"}]}}