Preparation, tissue localization and cardioselectivity of iodinated β- adrenergic receptor antagonists: Analogs of potential myocardial imaging agents

Iodinated β-adrenergic receptor antagonists were prepared to be investigated as potential myocardial imaging agents. The compounds are iodinated derivatives (1, 2 and 4) of non-cardioselective propranolol, nadolol and oxyfedrine, respectively, and an iodinated derivative (3) of the cardioselective acebutolol. The target derivatives were prepared by direct iodination of the clinically used drugs and injected into rats and their relative distribution in the target organ, the heart, and the non-target organs, lungs and blood was determined by measuring the iodine concentration in these tissues using a modification of the Sandell and Kolthoff assay. Binding assays, using heart and lung tissues, were conducted using H- propranolol as the radioligand. Compound 3 showed high binding selectivity to the cardiac β-adrenergic receptors. The radioiodinated derivatives of cardioselective β-adrenergic antagonists can be used as potential myocardial imaging agents.