Class (22) Structure Activity Relationship (SAR) of Beta Receptor Blockers | Medicinal Chemistry 01

Download the "Solution Pharmacy" Mobile App to Get All Uploaded Notes, Model Question Papers, Answer Papers, Online Tests and other GPAT Materials - https://play.google.com/store/apps/de... Solution Pharmacy will cover this syllabus of medicinal chemistry 01 for B.Pharmacy 4th semester Unit 02 – (01) Drug acting on the autonomic nervous system (02) Adrenergic neurotransmitters – biosynthesis and catabolism of catecholamine, adrenergic receptors, alpha-adrenergic receptor and beta-adrenergic receptor and the distribution of alpha and beta-adrenergic receptors (03) Sympathomimetic agents structure-activity relation (SAR) of sympathomimetic agents like direct acting – Nor-epinephrine, epinephrine, Phenylephrine, dopamine, methyldopa, clonidine, dobutamine, isoproterenol, terbutaline, salbutamol, bitolterol, naphazoline, oxymetazoline, and xylometazoline. (04) Indirect-acting agents – Hydroxy amphetamine, Pseudoephedrine, propylhexedrine, (05) Agents with a mixed mechanism (06) Adrenergic antagonist – (07) Alpha adrenergic blocker, tolazoline, Phentolamine, Phenoxybenzamine, prazosin, dihydroergotamine, mtyhlesergide. (08) Beta-adrenergic blockers – SAR of beta blockers, Propranolol, Metipranolol, Atenolol, Bisoprolol, esmolol, metoprolol, labetalol, carvedilol Beta-Adrenergic blockers Beta - blockers are among the most widely employed antihypertensive and are also considered the first line treatment for glaucoma. Most of the B-blockers are in the chemical class of aryloxypropanolamines. The first B- blocker, dichloroisoproterenol was reported in 1958. Non Selective blockers Propranolol SAR: 1. Lengthening of side chain prevent appropriate binding of required functional group to same receptor site 2. Propranolol is the most lipophilic drug among the available B-blockers. Therapeutic uses: Propranolol approved for use in angina pectoris, past myocardia infarction, hypertension, cardiac, migraine prophylaxis & essential tremor also used in CNS disorders. Atenolol Mechanism of action It is a type of selective B1 receptors antagonist, a drug belonging to the group of ß blocker used in treatment of cardiovascular diseases & hypertension. Therapeutic uses: Atenolol is used for a number of conditions including hypertension, angina, long QT syndrome, acute myocardial infarction, supraventricular tachycardia, ventricular tachycardia, and the symptoms of alcohol withdrawal. Metoprolol Mechanism of action Metoprolol blocks Beta 1 adrenergic receptors in heart muscle cells, thereby decreasing the slope of phase 4 in the nodal action potential (reducing Na+ uptake) and prolonging repolarization of phase 3 (slowing down K+ release). SAR 1. The presence of para substitute of sufficient size on the aromatic ring along with absence of Meta substitute is one of the common structural features of Beta 1-adrenoreceptor antagonist. 2. 4-substituted aryloxypropanolamines are selective B1 blockers. Therapeutic uses: It is used in treatment of hypertension, acute myocardial infarction, angina supraventricular & ventricular tachycardia. It is also used in treatment of migraine headaches & congestive heart failure. Mixed alpha/beta Adrenergic Antagonist Labetalol and Carvedilol Mechanism of action: Both drugs are antihypertensive with al, B1 & B2 blocking activity. SAR 1. If we replace t-butyl or isopropyl group of alpha 1 -receptor agonist by larger groups the agonistic activity decreases and antagonistic activity increases. 2. Carvedilol has an estimated Beta blocking activity 10-100 times it's a- blocking activity. 3. Labetalol has more potent Beta-antagonist than alpha-agonist & it has two asymmetric carbon atoms & it exists as a mixture of four isomers. 4. In labetalol Beta-blocking activity shown by (1R, 1'R) isomers alpha l -antagonistic activity shown by (1S, 1'R) isomers. Greater activity showed by (1S, 1'R) isomers. 5. Carvedilol is Beta blocker that possesses alpha -adrenergic receptor blocking activity & only (S) enantiomer possesses the Beta-blocking activity. While both enantiomers are antagonists of alpha 1 -receptor. E-Mail for official and other work - solutionpharmacy@gmail.com #solutionpharmacy #Pharmacologyclass #Pharmacognosyvideos #GPAT