Propranolol glycol is a major metabolite of propranolol in man with potent anticonvulsant activity. Propranolol glycol appears to be more potent for this effect than propranolol. The onset of action of propranolol glycol is instantaneous but delayed for propranolol. Maximal anticonvulsant activity for propranolol glycol is obtained immediately and for propranolol 10 minutes after administration. The delayed onset of this action of propranolol and the immediate anticonvulsant activity of propranolol glycol strongly suggest that the anticonvulsant properties of propranolol may be related to its conversion to propranolol glycol. Propranolol and propramioiol glycol have a similar spectrum of gross behavioral effects ranging from quietness at low doses to paralysis at high doses. These observations suggest the possibility that propranolol glycol may be contributing to some of the therapeutically significant effects of propranolol in the central nervous system.

(-)-Propranolol is a small molecule β-adrenergic receptor antagonist and the active isomer of (±)-Propranolol preparations. (-)-Propranolol blocks the binding of epinephrine, norepinephrine, and other endogenous catecholamines to the β-adrenergic receptor, impeding increases in cardiac flow velocity and general stimulation of the sympathetic nervous system signaled by the association of these molecules to the β-adrenergic receptor. In addition to blockade of agonist binding, antagonism of the β-adrenergic receptor by (-)-Propranolol produces negative chronotropic and inotropic action, effectively dampening the force and rate of cardiac contraction. These negative chronotropic and inotropic effects correlate to a demonstrated suppression of adrenaline-induced cardiac arrhythmia by (-)-Propranolol. Suppression of β-adrenergic receptor activation by (-)-Propranolol has been widely exploited in counteracting situations sensitive to heightened cardiac activity including hypertension, angina pectoris, and cardiac ischemia.