THE IN-VITRO CHARACTERIZATION AND BIOSTABILITY OF TC-99M-DEXTRAN AND ITS ACCUMULATION WITHIN THE INFLAMED PAWS OF ADJUVANT-INDUCED ARTHRITIC RATS

The in vitro and in vivo stability in normal and adjuvant-induced arth ritic rats of Tc-99-dextrans (10, 40 and 500 kDa) have been investigat ed. The circulation half-lives were molecular weight dependent, with 1 0 and 40 kDa fractions being cleared relatively rapidly due to their a bility to cross the glomerular basement membrane. The 500 kDa dextran was eliminated more slowly although 79% had been removed from the circ ulation 4 h post injection which probably was due to its degradation b y dextranases and subsequent glomerular excretion. Dextran accumulatio n by the RES was found to be similar for all molecular weight preparat ions with no significant differences found. The sequestration of the d extrans by tissues of the RES (liver, spleen and lung) was independent of clearance rate. No differences were seen between normal and arthri tic groups. Accumulation of the polymers by inflamed paws greatly exce eded that of normal paws for the 10 kDa (5-fold) and 500 kDa (6-fold) although no differences were seen with the 40 kDa dextran.