Propranolol ß-adrenergic blocking agent, reduces cardiac activity by diminishing or preventing ß-adrenergic stimulation. It reduces the rate and force of contraction of the heart and prolongs A-V conduction time. In response to the inhibition of the ß-receptors, the oxygen requirement diminishes which proves beneficial in cases of angina pectoris. The blood pressure in hypertensive patients is also reduced because of this effect.
Its principal effect is to reduce the response of the heart to stress and exercise and it reduces blood pressure in patients with hypertension.
Peak plasma concentrations occur about 1 to 2 hours after an oral dose. Propranolol is more than 90% bound to plasma proteins. It is metabolised in the liver, the metabolites being excreted in the urine together with only small amounts of unchanged propranolol. The plasma half-life of propranolol is about 3 to 6 hours, the biological half-life being longer than plasma half-life.
Propranolol crosses the blood-brain barrier and the placenta and is distributed into breast milk.