Pathways

Propranolol, a non-cardioselective beta blocker, inhibits sympathetic stimulation by competing with neurotransmitters like catecholamines to bind beta(1)-adrenergic receptors of the heart and vascular smooth muscle. Propranolol binding reduces resting heart rate, cardiac output, blood pressure and orthostatic hypotension. Propranolol also reduce sympathetic activity to manage hyperthyroidism, anxiety and tremor. Propranolol also competes for beta(2)-adrenergic receptors on bronchial and vascular smooth muscles.

On the World Health Organization's List of Essential Medicines and a prototypical drug of its class, propranolol is a non-cardioselective beta blocker and it is typically synthesized as a racemic mixture of 2 enantiomers where the S(-)-enantiomer has approximately 100 times the binding affinity for beta adrenergic receptors. It can be administered intravenously to the bloodstream or orally, where it passes through hepatic portal circulation, and enters the bloodstream to act on peripheral cells. This pathway focuses on cardiovascular effects of propranolol but as a relatively lipophilic drug, it can accumulate in the brain. In the brain, it antagonizes serotonergic receptors and inhibits (via receptor antagonism) adrenergic receptors - its psychiatric effects are under research currently. It may also be used for infant hemangioma. In the periphery, propranolol can target beta-1, beta-2, and beta-3 adrenergic receptors (hence its reduced selectivity compared to newer beta blockers, which has clinical implications in the treatment of dysrhythmias) to interfere with the normal epinephrine to adrenergic receptor binding, thus acting as a competitive antagonist - its cardiovascular effects on the beta-1 adrenergic receptor are responsible for its primary therapeutic use as a class II antidysrhythmic agent. It is also an antihypertensive and antianginal agent. In bronchial and vascular smooth muscle, propranolol can compete with epinephrine for beta-2 adrenergic receptors. By competing with catecholamines for adrenergic receptors, it inhibits sympathetic stimulation of the heart. The reduction of neurotransmitters binding to beta receptor proteins in the heart inhibits adenylate cyclase type 1. Because adenylate cyclase type 1 typically activates cAMP synthesis, which in turn activates PKA production, which then activates SRC and nitric oxide synthase, its inhibition causes the inhibition of cAMP, PKA, SRC and nitric oxide synthase signaling. Following this chain of reactions, we see that the inhibition of nitric oxide synthase reduces nitric oxide production outside the cell which results in vasoconstriction. On a different end of this reaction chain, the inhibition of SRC in essence causes the activation of Caspase 3 and Caspase 9. This Caspase cascade leads to cell apoptosis. The net result of all these reactions is a decreased sympathetic effect on cardiac cells, causing the heart rate to slow and arterial blood pressure to lower; thus, propranolol administration and binding reduces resting heart rate, cardiac output, afterload, blood pressure and orthostatic hypotension. By prolonging diastolic time, it can prevent re-infarction. One potentially less than desirable effect of non-selective beta blockers like propranolol is the bronchoconstrictive effect exerted by antagonizing beta-2 adrenergic receptors in the lungs. Clinically, it is used to increase atrioventricular block to treat supraventricular dysrhythmias. Propranolol also reduce sympathetic activity to manage hyperthyroidism, anxiety and tremor. As a result, propranolol is used to treat hypertension, angina, migraine headaches, and hypertrophic subaortic stenosis.

On the World Health Organization's List of Essential Medicines and a prototypical drug of its class, propranolol is a non-cardioselective beta blocker and it is typically synthesized as a racemic mixture of 2 enantiomers where the S(-)-enantiomer has approximately 100 times the binding affinity for beta adrenergic receptors. It can be administered intravenously to the bloodstream or orally, where it passes through hepatic portal circulation, and enters the bloodstream to act on peripheral cells. This pathway focuses on cardiovascular effects of propranolol but as a relatively lipophilic drug, it can accumulate in the brain. In the brain, it antagonizes serotonergic receptors and inhibits (via receptor antagonism) adrenergic receptors - its psychiatric effects are under research currently. It may also be used for infant hemangioma. In the periphery, propranolol can target beta-1, beta-2, and beta-3 adrenergic receptors (hence its reduced selectivity compared to newer beta blockers, which has clinical implications in the treatment of dysrhythmias) to interfere with the normal epinephrine to adrenergic receptor binding, thus acting as a competitive antagonist - its cardiovascular effects on the beta-1 adrenergic receptor are responsible for its primary therapeutic use as a class II antidysrhythmic agent. It is also an antihypertensive and antianginal agent. In bronchial and vascular smooth muscle, propranolol can compete with epinephrine for beta-2 adrenergic receptors. By competing with catecholamines for adrenergic receptors, it inhibits sympathetic stimulation of the heart. The reduction of neurotransmitters binding to beta receptor proteins in the heart inhibits adenylate cyclase type 1. Because adenylate cyclase type 1 typically activates cAMP synthesis, which in turn activates PKA production, which then activates SRC and nitric oxide synthase, its inhibition causes the inhibition of cAMP, PKA, SRC and nitric oxide synthase signaling. Following this chain of reactions, we see that the inhibition of nitric oxide synthase reduces nitric oxide production outside the cell which results in vasoconstriction. On a different end of this reaction chain, the inhibition of SRC in essence causes the activation of Caspase 3 and Caspase 9. This Caspase cascade leads to cell apoptosis. The net result of all these reactions is a decreased sympathetic effect on cardiac cells, causing the heart rate to slow and arterial blood pressure to lower; thus, propranolol administration and binding reduces resting heart rate, cardiac output, afterload, blood pressure and orthostatic hypotension. By prolonging diastolic time, it can prevent re-infarction. One potentially less than desirable effect of non-selective beta blockers like propranolol is the bronchoconstrictive effect exerted by antagonizing beta-2 adrenergic receptors in the lungs. Clinically, it is used to increase atrioventricular block to treat supraventricular dysrhythmias. Propranolol also reduce sympathetic activity to manage hyperthyroidism, anxiety and tremor. As a result, propranolol is used to treat hypertension, angina, migraine headaches, and hypertrophic subaortic stenosis. It can be found under the brand names Hemangeol, Hemangiol, Inderal, and Innopran. Some side effects of using propranolol may include dizziness, tiredness, and difficulties sleeping. Propranolol is administered as an oral capsule or tablet.

On the World Health Organization's List of Essential Medicines and a prototypical drug of its class, propranolol is a non-cardioselective beta blocker and it is typically synthesized as a racemic mixture of 2 enantiomers where the S(-)-enantiomer has approximately 100 times the binding affinity for beta adrenergic receptors. It can be administered intravenously to the bloodstream or orally, where it passes through hepatic portal circulation, and enters the bloodstream to act on peripheral cells. Propranolol is a non-selective beta adrenergic antagonist used to treat hypertension, angina, atrial fibrillation, myocardial infarction, migraine, essential tremor, hypertrophic subaortic stenosis, and pheochromocytoma. It can be found under the brand names Hemangeol, Hemangiol, Inderal, and Innopran. Propranolol causes vasoconstriction via blockage or antagonism of the beta-2 adrenergic receptors. By blocking these receptors, the G protein signalling cascade is unable to occur, leading to increased levels of intracellular calcium which can then readily bind to calmodulin causing smooth muscle contraction (vasoconstriction in this case). Some side effects of using propranolol may include dizziness, tiredness, and difficulties sleeping.

Propyl alcohol is a drug that is not metabolized by the human body as determined by current research and biotransformer analysis. Propyl alcohol passes through the liver and is then excreted from the body mainly through the kidney.

Propylene glycol is a drug that is not metabolized by the human body as determined by current research and biotransformer analysis. Propylene glycol passes through the liver and is then excreted from the body mainly through the kidney.

Propylhexedrine is a drug that is not metabolized by the human body as determined by current research and biotransformer analysis. Propylhexedrine passes through the liver and is then excreted from the body mainly through the kidney.