212Pb/212Bi-EDTMP — synthesis and biodistribution of a novel bone seeking alpha-emitting radiopharmaceutical
✍ Scribed by Sindre P. Hassfjell; Per Hoff; Øyvind S. Bruland; Jorolf Alstad
- Publisher
- John Wiley and Sons
- Year
- 1994
- Tongue
- French
- Weight
- 671 KB
- Volume
- 34
- Category
- Article
- ISSN
- 0022-2135
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✦ Synopsis
Abstract
At present, haematological toxicity is dose limiting in radionuclide therapy of bone metastases, and there is a need for radiopharmaceuticals with improved tumour/bone marrow dose ratios. Therefore, α‐emitters e.g. ^212^Bi may be more suitable than β‐emitters, because of the short range and high LET values of α‐particles. In this study, ^212^Bi and its mother nuclide ^212^Pb were produced in an isotope generator by collecting gaseous ^220^Rn emanating from barium (^228^Th) stearate. The carrier‐free ^212^Pb/^212^Bi were bound to the chelating bone‐seeking compound ethylene‐diamine‐tetra(methylene‐phosphonic acid) (EDTMP) with 90% yield. The biodistribution in Balb/c mice was investigated by injecting 100 μl of a saline PBS buffer 0.020 M in EDTMP and 10 MBq/ml in ^212^Pb/^212^Bi. Mice were killed in groups of three at 0.5, 2, 13 and 24 h post‐injection times. Both ^212^Pb‐EDTMP and ^212^Bi‐EDTMP localised strongly in the skeleton, especially in the femur, at all time points measured, with the % of injected dose per gram (%ID/g) as high as 15 for ^212^Pb and 13 for ^212^Bi. All other organs investigated showed low uptake of both radionuclides, with the exception of the kidneys, for which a ratio femur/kidney of 1.5 for ^212^Bi 2 h postinjection was observed. By comparison the ratio femur/blood was 20 for ^212^Bi 2 h postinjection. The experiment indicates a potential for ^212^Pb/Bi‐EDTMP in targeted radiotherapy of osteoblastic bone lesions.