Kg. Grillenberger et al., RE-188 LABELED HYDROXYAPATITE AND RE-188 SULFUR COLLOID - IN-VITRO COMPARISON OF 2 AGENTS FOR RADIATION SYNOVECTOMY, Nuklearmedizin, 36(2), 1997, pp. 71-75
Aim: One therapeutic approach to rheumatoid arthritis and other inflam
matory arthropathies besides surgical removal of inflamed synovium is
radiation synovectomy using beta-emitting radionuclides to destroy the
affected synovial tissue. Up to now the major problem associated with
the use of labeled particles or colloids has been considerable leakag
e of radionuclides from the injected joint coupled with high radiation
doses to liver and other non target organs. in this study we compared
Re-188 labeled hydroxyapatite particles and Re-188 rhenium sulfur col
loid for their potential use in radiation synovectomy. Methods: To thi
s end we varied the labeling conditions (concentrations, pH-value, hea
ting procedure) and analyzed the labeling yield, radiochemical purity,
and in vitro stability of the resulting radiopharmaceutical. Results:
After optimizing labeling conditions we achieved a labeling yield of
more than 80% for Re-188 hydroxyapatite and more than 90% for the rhen
ium sulfur colloid. Both of the radiopharmaceuticals can be prepared u
nder aseptic conditions using an autoclav for heating without loss of
activity. In vitro stability studies using various challenge solutions
(water, normal saline, diluted synovial fluid) showed that Re-188 lab
eled hydroxyapatite particles lost about 80% of their activity within
5 d in synovial fluid. Rhenium sulfur colloid on the other hand proved
to be very stable with a remaining activity of more than 93% after 5
d in diluted synovial fluid. Conclusion: These in vitro results sugges
t that Re-188 labeled rhenium sulfur colloid expects to be more suitab
le for therapeutic use in radiation synovectomy than the labeled hydro
xyapatite particles.