Serum stability of 67Cu chelates: Comparison with 111In and 57Co

https://doi.org/10.1016/0883-2897(86)90011-5Get rights and content

Abstract

Simple chelates and chelate conjugated monoclonal antibodies labeled with 111In, 57Co and 67Cu demonstrate marked differences in stability when exposed to a serum environment. Among these radiometals, on DTPA, the order of stability is 111In 57Co ⪢ 67Cu. On benzyl-EDTA, the order of stability is 111In ⋍ 57Co ⪢ 67Cu. Among those investigated, the only serum stable 67Cu chelate found was 67Cu-TETA. The order of stability observed for 57Co vs 67Cu is contrary to published equilibrium constants. These in vitro studies suggest that the in vivo behavior of metal chelates exposed to a complex molecular environment may not be predicted by classically determined equilibrium constants.

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    Supported by the U.S. Department of Energy AT03-82 and the National Cancer Institute CA16861.

    Present address: Department of Nuclear Medicine, The Methodist Hospital/Baylor College of Medicine, Houston, Texas, U.S.A.

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