(R)-Alprenolol is a less active stereoisomer of antihypertensive beta-blocker alprenolol. Its activity against beta-adrenoreceptor is 100 times lower than the activity of (S)-alprenolol. In a model of ventricular arrhythmias produced by ligation of the left coronary artery, (R)-alprenolol was effective at 15.5 mg/kg, whereas (S)-alprenolol abolished the ventricular arrhythmia by cumulative dose of 7.5 mg/kg.

(S)-Alprenolol is a more active stereoisomer of antihypertensive beta-blocker alprenolol. Its activity against beta-adrenoreceptor is 100 times greater than the activity of (R)-alprenolol. In a model of ventricular arrhythmias produced by ligation of the left coronary artery, (S)-alprenolol was effective at 7.5 mg/kg, whereas (R)-alprenolol abolished the ventricular arrhythmia by cumulative dose of 15.5 mg/kg. As a most active enantiomer of alprenolol, the compound was used as a tool to study beta-adrenergic receptors.