Selectivity in New β-Adrenergic Blocking Agents. (3-Amino-2-hydroxypropoxy)benzamides

The β-adrenergic receptor blocking properties of new open-chain and lactam-type benzamido analogs of practolol (2) were investigated. These compounds display a competitive blocking activity on both vascular and myocardial β receptors. However, subtle structural changes in the aromatic moiety profoundly affected their organ specificity toward each of these receptors. Since all of the test compounds including practolol (2) share similar lipohydrophilic character, it may be concluded that their ability to selectively block either myocardial or vascular receptors depends primarily on electronic and steric factors.