QUADRAMET® IS A THERAPEUTIC AGENT CONSISTING OF RADIOACTIVE SAMARIUM AND A TETRAPHOSPHONATE CHELATOR, ETHYLENEDIAMINETETRAMETHYLENEPHOSPHONIC ACID. IT EMITS BOTH MEDIUM-ENERGY BETA PARTICLES AND A GAMMA PHOTON, AND HAS A PHYSICAL HALF-LIFE OF 46.3 HOURS (1.93 DAYS).
SAMARIUM SM-153 EDTMP) HAS AN AFFINITY FOR BONE AND CONCENTRATES IN AREAS OF BONE TURNOVER IN ASSOCIATION WITH HYDROXYAPATITE. IN CLINICAL STUDIES EMPLOYING PLANAR IMAGING TECHNIQUES, MORE QUADRAMET® ACCUMULATES IN OSTEOBLASTIC LESIONS THAN IN NORMAL BONE WITH A LESION-TO-NORMAL BONE RATIO OF APPROXIMATELY 5. THE MECHANISM OF ACTION OF QUADRAMET® IN RELIEVING THE PAIN OF BONE METASTASES IS NOT KNOWN.