ANALYSIS OF URINE SAMPLES FROM METASTATIC BONE CANCER-PATIENTS ADMINISTERED SM-153 EDTMP

Sm-153-EDTMP is currently undergoing clinical evaluation as a radiothe rapeutic agent for the relief of pain associated with cancer metastati c to bone. These clinical studies have demonstrated biodistributions s imilar to those seen earlier in animals, namely, rapid clearance from blood, selective uptake in bone and in particular metastatic bone lesi ons. The radioactivity not deposited in bone is cleared through the ki dneys into the urine. In this study, urine samples collected from 9 pa tients injected with Sm-153-EDTMP underwent complexation analysis via Pharmacia SP Sephadex(R) C25 cation exchange chromatography. The resul ts showed 96.9 +/- 1.7% of the radioactivity in the urine to be presen t as a complex of Sm-153. An HPLC method was developed and it was demo nstrated that different complexes of Sm-153 could be separated. A non- radioactive analytical standard of the Sm-EDTMP chelate was synthesize d, characterized and shown to have the same HPLC retention profile as the Sm-153 EDTMP drug product. HPLC analysis was performed on six urin e samples and in each case a single radioactivity peak with an elution profile the same as that of a Sm-153-EDTMP standard was observed. The se results indicate that the Sm-153-EDTMP chelate is excreted intact i n the urine of patients.