[153Sm]EDTMP: a potential therapy for bone cancer pain.

Reactor-produced samarium-153 (153Sm) is both a beta and gamma emitter with a physical half-life of 46.3 hours. When complexed with EDTMP, more than 50% of the administered dose localizes in bone. A therapeutic trial on patients with painful bone metastases performed at the University of Missouri produced relief in 65.4% of the patients who were evaluable. Myelotoxicity was mild and transient. For [153Sm]EDTMP to attain clinical utility, studies demonstrating its efficacy as an analgesic must be performed to exclude a "ligand analgesic effect".