In vivo metabolism of the technetium isonitrile complex [Tc(2-ethoxy-2-methyl-1-isocyanopropane)6]+.

Technetium(2-ethoxy-2-methyl-1-isocyanopropane)6+, [Tc-EIBT] is a complex of technetium(I) structurally similar but slightly more lipophilic than the commercial myocardial perfusion agent Cardiolite [Tc-MIBI]. Tc-EIBI exhibits rapid extraction from the blood into heart, liver, kidney and striated muscle and rapid hepatobiliary clearance. In the guinea pig, unlike Tc-MIBI, this compound is almost completely enzymatically metabolized to numerous cationic complexes containing a mixture of ethyl other and hydroxy isonitrile ligands. Substitution of the ethyl other group for a methyl ether produces an agent that shows selective in vivo metabolism and more rapid clearance from the liver.