(R)-Propranolol (hydrochloride)

(R)-Propranolol hydrochloride is a less active enantiomer of the β-adrenoceptor antagonist propranolol (HY-B0573). Propranolol is a nonselective β-adrenergic receptor (βAR) antagonist, has high affinity for the β₁AR and β₂AR with K_i values of 1.8 nM and 0.8 nM, respectively^[1]. In Vivo: Both isomers of propranolol are capable of preventing adrenaline-induced cardiac arrhythmias in cats anaesthetized with halothane, but the mean dose of (-)-propranolol is 0.09 mg/kg whereas that of (+)-propranolol is 4.2 mg/kg^[1].
Both isomers of propranolol are capable of reversing ventricular tachycardia caused by ouabain in anaesthetized cats and dogs. The dose of (-)-propranolol is significantly smaller than that of (+)-propranolol ((R)-Propranolol) in both species^[1].
(R)-Propranolol hydrochloride (10 mg/kg) has no antagonistic activity in rats, the cardiac responses to isoprenaline of rat can be blocked by probably much less than 1/100th of that of the (-) isomer in this preparation^[1].