Will Alteration of Radiostrontium Biodistribution by Chlorthalidone Improve Therapy of Painful Bone Metastases?
John J. Coupal, Unified HealthCare Nuclear Pharmacy, LLC, 11700 Commonwealth Drive, Suite 700, Louisville KY 40299 USA Strontium-89 chloride in aqueous solution (MetastronTM; FDA approved; single dose of 148 MBq) is injected intravenously for pain relief in patients suffering metastases of prostate and breast cancer. Speculation exists about mechanisms responsible for the pain palliation that lasts up to six months. Renal clearance of bone seeking Sr-89 (radioactive half-life 50.5 days) in humans is the main factor determining total-body Sr-89 retention for up to six days post-injection. An inverse relationship exists between the magnitude of total Sr-89 excretion and the extent plus severity of existing osteoblastic lesions. That therapy, however, is far from ideal. My earlier attempts (in 1969) employed several individual diuretics to enhance excretion of injected Sr-85 from normal laboratory rats. The studies revealed that only the monosulfamyl diuretic chlorthalidone prolonged Sr-8
