15-(p[75Br]bromophenyl)pentadecanoic acid: pharmacokinetics and potential as heart agent.

Preparation, quality control, and pharmacokinetics of 15-(p-[75Br]bromophenyl)pentadecanoic acid (BPPA) were studied, with particular emphasis on the fate of the label and the usefulness of BPPA as a heart agent. BPPA labeled with the positron emitter Br-75 (T 1/2 = 98 min) was prepared in 55% radiochemical yield with a specific activity of greater than or equal to 1000 Ci/mmol. While the uptake of BPPA in the heart muscle is as fast and efficient as that of aliphatic omega-halofatty acids, its elimination is delayed, owing mainly to an inhibited beta oxidation and the formation of lipophilic catabolites. The blood activity and its time course are identical to those of omega-halofatty acids, but no free bromide appears in any body fluid or organ. The complex pharmacokinetic behavior of stable lipophilic catabolites prevents a quantitative background correction. In contrast to aliphatic omega-halofatty acids, a quantitative evaluation of myocardial metabolism is not possible. Br-75 BPPA, however, is well suited for positron emission tomography of the heart.