Lack of effect of a bisphosphonate (pamidronate disodium) infusion on subsequent skeletal uptake of Sm-153 EDTMP.

Patients who are candidates for samarium-153 ethylenediaminetetramethylenephosphonic acid (Sm-153 EDTMP) therapy often receive monthly infusions of pamidronate disodium or other bisphosphonates. Because both drugs are related compounds that concentrate in bone, it was advisable to determine whether previous bisphosphonate administration has blocked subsequent uptake of Sm-153 EDTMP. The authors compared skeletal uptake of Sm-153 EDTMP before and 1 to 4 days after pamidronate infusion in three patients with breast cancer metastatic to bone. In two of the patients, they continued to compare Sm-153 EDTMP uptake at approximately 1, 2, 3, and 4 weeks after pamidronate infusion. There was no difference in skeletal uptake of Sm-153 EDTMP before or at any time after pamidronate infusion. Pamidronate infusion did not interfere with skeletal uptake of Sm-153 EDTMP.