Re: Sr Biological Half-Life

[Karin Gordon <kgordon@cc.UManitoba.CA>]

You might want to contact Amersham for a copy of its product monograph
on Metastron, which is Sr-89 strontium chloride injected IV for
palliation of pain from bony metastastic lesions, usually secondary to
cancer of the prostate and breast.   The monograph (which has a number
of very good references) summarizes Sr excretion kinetics.  Strontium is
a calcium analogue and localises in bone mineral, especially at sites of
increased bone turnover.  Metastatic bone lesions accumulate strontium
more than normal bone. The strontium not taken up by bone is rapidly
cleared  by the kidneys and excreted primarily in the urine.  The
percentage of renal clearance is directly related to the extent of  the
metastatic disease.  It appears that the normal biological T1/2 for Sr
injected IV is approximately 3 days, and the whole body retention at 3
months is about 20%.   In one study of patients with metastatic bone
disease the whole body retention at 3 months varied from 11% to 88%
depending on the degree of skeletal involvement.

Karin Gordon
Radiation Safety Officer
Health Sciences Centre
GC-214, 820 Sherbrook St
Winnipeg, MB, Canada

phone        (204) 787-2903
fax            (204) 787-1313
e-mail        kgordon@cc.umanitoba.ca



Dale E. Boyce wrote:

> Does anyone have any info on the excretion fraction of Sr
> administered by injection?