123I-iodobenzoylglucosamines: glucose analogues for heart imaging

The ortho-, meta- and para-[123I]-2-deoxy-2-N-(iodobenzoyl)-D-glucosamine (BGA) derivatives were investigated to determine the effect of iodine position and lipophilicity on tissue distribution. There was no correlation between tissue uptake and lipophilicity. Maximum uptake was observed for o-BGA displaying a heart:blood ratio of 36.0 at 18 hours post injection. Yeast hexokinase phosphorylation studies in vitro and an in vivo insulin experiment were carried out on o-BGA. No phosphorylation was detected, but the insulin study indicated that o-BGA uses the glucose transporter. o-BGA showed maximum tissue uptake in mice at an optimal specific activity of 0.004mg/μCi. Mouse biodistribution studies of o-[123I]-iodobenzamide(o-123IBA) indicated that the glucose moiety of o-BGA may be involved in the heart accumulation process in mice. Heart tissue extraction studies showed unmetabolized o-[123I]BGA was the predominant species. A rabbit image of o-[123I]BGA, recorded at 14 hours post injection, showed significant heart uptake. (author)