Propranolol, one of the first β-blockers used in cardiovascular medicine, inhibits β1-, β2-, and β3-adrenergic receptors with log KD values of -8.16, -9.08, and -6.93, respectively. Ring-hydroxylated isomers of propranolol also antagonize β-adrenergic receptors and demonstrate potent vasodilator activity. rac-7-methoxy Propranolol is an intermediate for the preparation of rac-7-hydroxy propranolol.