Skip to content


  • by

Hope you like the video and hope it helps you in better understanding of the concepts.

Hello my dear students we are going to discuss the adrenergic blocking agents and as you know the alpha receptors and their beta receptors so there could be alpha receptor blocking agents beta receptor blocking agents and some agents who could block the alpha as well as the beta receptors we first start discussing the alpha blockers let me remind you alpha

Receptor is mainly present in the peripheral blood vessels and this leads to ways of constriction and obviously when you block these alpha receptors you’re going to get vasodilation and that’s going to lead to fall in the blood pressure the thing doesn’t stop here whenever there is vasodilation the heart is going to go into reflex tachycardia which manifests as

Palpitation in the patient the patient is likely to get a throbbing headache due to the vasodilation flushing of the face and it could also precipitate in china because it’s going to increase the workload on the heart because alpha blockers are producing vasodilation there’s going to be increased venous capacitance and there’s going to be decreased venous return

And this could manifest into postural hypotension and syncope sinkable attacks especially when an alpha blocker is used for the first time that the first dose of of an alpha blocker is likely likely to produce a same couple attack and that’s called the first dose effect we need to keep this in mind whenever we discuss the alpha blockers all the effects based on

Wage dilation namely reflex star tachycardia palpitations robbing headache flushing and precipitation of angina as well as the first dose effect or the posterior hypotension let’s classify alpha blockers let’s have a look at the slide there are non-selective alpha blockers which block alpha one as well as alpha two receptors which could be irreversible that’s long

Acting example is phenoxy benzamine i would like to remind you of inoxybenzamine as an example of non-competitive inhibition the second group is reversible that short-acting very important short acting drug is pain tolerane and along with it it is tolazolin and coming to the selective that’s alpha one selective blockers you have brazosin doxazosin terazosine and

The newer ones alphys ocean and tam celestine there is also an alpha two selective agent alpha two selective blocker called yohimbine alpha blockers contain phenoxybenzamine which is a long acting agent and i told you it produces a non-surmountable antagonism due to the covalent binding and it’s useful in the long term treatment of pure chromosyatoma you need

To block the alpha receptors first and then start the beta blockers phenytalamine is a short acting agent and is useful by intravenous root of administration the dose of five milligrams for diagnosis of fear chromosyatoma as well as the short-term treatment of fear chromosyatoma when you want to deal with an emergency dollar zolan is useful by oral and parental

Roots in the neonats especially to treat the pulmonary hypertension that’s the parental route of administration for tolazzolin alpha blockers which are alpha one selective contain an important drug called prison is going to lead to vasodilation is going to dilate the resistance vessels the capacitance vessels is going to decrease the preload and afterload on

The heart because the resistance vessels are dilated and the capacitance vessels are also dilated it will decrease the blood pressure the importance of brazilian is it produces comparatively less reflux tachycardia when you want to start it orally always start in a smaller dose that’s point five milligrams two times a day and this is useful for mild to moderate

Hypertension and acute congestive heart failure don’t forget the first dose effect with prostate first time you give it is likely to block the alpha receptor and when you try to change your posture it’s going to lead to partial hypotension or a sinkable attack terrazosine and doxazosin are important when the patient suffers from hypertension as well as the

Patient has benign prostatic hypoglycemia doxazosin is a long-acting agent and acts for 22 hours benign prostatic hypoplasia is also important because you’ve got two neon agents one is alfies ocean and the second one is tam cerrosine dam silasin is selective at alpha one a receptors and alpha d receptors alpha one a receptor blockade is extremely important

Because this is going to decrease the smooth muscle tone in the bladder neck in the bladder base the prosthetic capsule the prosthetic urethra is going to decrease the resistance to blood flow and is going to improve the urine flow and that’s why tamsulosine is useful in a benign prosthetic hypoplasia to produce the symptomatic relief in the patient or when the

Patient has urinary obstruction now they revise the adverse effects of beta blockers common adverse effects as i said are going to be reflex tachycardia which is less with processing than palpitation flushing of face throbbing headache and postural hypotension first was effect with brazosin and because alpha one receptor is going to be blocked there will be

Meiosis leading to blurring of vision alpha when blockade will also lead to nasal congestion and the failure of ejaculation also due to alpha one plucket let’s have a review let’s look at this particular slide all the alpha blockers are summarized on this slide brazosin the first one is useful in the management of hypertension in the management of heart failure

Because it decreases the preload and afterload and is also useful in the management of p of chromosome trauma femtolamine is a short acting agent and is mostly used by intravenous root of administration to treat emergency hypertension and emergency management of pheochromocytoma doxazosin and terrorism as you go down also start having an effect on the prostate

And it’s useful when the patient has hypertension as well as the benign prostatic hypoplasia whereas if you come to tamzillosin it’s got less effect as far as the blood vessel peripheral blood vessels are concerned and it’s more selective at the alpha one a receptor concerned with the prostate and that’s why tamsillerson is useful in benign prostatic hypoplasia

There could be some drugs which block the alpha receptors but they also block the beta receptors these are the combined alpha beta blockers includes metroxolol carvedilol lavatory lol and business law they are useful in the management of hypertension heart failure and fear chromocytoma now we come to the beta blockers have a nice look at this particular slide

I’ve exerted on this slide particularly because you should be able to revise all your beta blocker classification with the help of just one single slide on the left side left hand side you have non-selective beta blockers and on the right hand side you have cardioselective beta blockers the non-selective ones are also called generation one beta blockers and the

Cardiac selective are also called generation two beta blockers although we are calling it cardio selective the real meaning is they are more selective at the beta 1 receptors because the beta 1 is in the heart there’s a trend to call them cardio selective beat blockers amongst the beta blockers which have been shown on this particular slide i have made some of the

Drugs in bold fonts i’ll read the ones which are in the bold fonts propranolol neutral timolol and sotolol on the non-selective side artemylol metoprolol asmulol bisoprolol bitoxalol celiprolol and nebivolol on the right hand side why did i make it bold i want you to remember that those drugs which have been written in both letters are one which are commonly

Used are the ones which are most commonly used so if you want to remember about the beta blockers at least don’t forget these ones which are most commonly used amongst all these drugs you would also find that in front of few beta blockers i have written an alphabet a look here like in front of propranolol there is a sotalol there is a in front of metroprolol

And acemolol i have written a please remember the key this a stands for arithmetic and these are the beta blockers which are commonly used for the management of arithmeas apart from this this particular slide is also showing you some important things if you go down on the non-selective side you’re finding three blockers which have been shown in a different font

That’s binder lol cartier lol and pen but all the purpose of writing them in a different font is you need to remember these are the better blockers with intrinsic sympathy magnetic activity that’s called isa intrinsic sympathetic activity pendulum cartilage and pain butyl and finally if you go down there are four drugs written in a slant and they’re written

In italics that’s metroxylal carbidilolol labetalol and bucinder lol i am trying to show them separately in the in italic letters because these are the drugs which are blocking the alpha receptors as well as beta receptors so they have got a capacity to block both the receptor what i mean to say is try to bring this slide in front of your mind and probably you

Will be getting all the beta blockers at one place the combined alphabet blocking agents which have been shown in italics here are also these days called generation three beta blockers they are combined alpha beta blockers and will be useful when you want to block both the receptors like situations of eochromocytoma chronic congestive heart failure and in the

Management of hypertension once again to revise the examples are lab etylol carvadillol metroxylol and business what is this intrinsic sympathetometic activity i mentioned intrinsic sympathetic activity is saying that these drugs are not pure and cornish at beta receptors they have got a certain partial agonistic activity and because they are partial agonistic

Activity they are going to produce less adverse effects as compared to the other beta blockers the beta agonist activity can lead to certain amount of bronchodilation whereas beta blockers are known to produce bronchospasm there will be less effect on the glucose and lipid metabolism these drugs include asbutylol pindolol benbutylolol cartilolol carbidilolol

And lobetrolol this carbidulol is important because it has been shown to decrease the peroxidation it has been shown to decrease the wall thickening and this is why cavity lol is preferred in patients with congestive heart failure labit law is useful to treat the pregnancy-induced hypertension and is also useful in the hypertensive crisis let me mention about

A special drug that’s t-molar malleat there’s a better blocker and this could be useful for chronic management of glaucoma it works by decreasing the aqueous humor production and there’s no change in the size of people is available as eye drops in addition to this you have a cardio selective beta blocker betaxalal longest acting beta blocker levobunylol cartel

Lol levobitoxolol and mitoplanolol all of them could be useful in the management of glaucoma now we go to discuss the toxicity of beta blockers remembering proven law as the prototype remember it’s going to block the beta receptors and if it’s non-selective it’s going to block beta 1 as well as b2 receptors so when you start blocking the beta2 receptors is going

To lead to bronchospasm and is going to precipitate conditions like bronchial asthma or the patients who suffer from chronic obstructive pulmonary diseases are going to get bronchospasm the second important beta2 receptor is present in the liver and we are going to block this beta2 receptor what’s going to happen is in response to hypoglycemia the liver is not

Going to bring in the glucose to the systemic circulation so what’s going to happen is this patient is not going to respond to hypoglycemia which is called hypoglycemia on responsiveness and this will be very important condition of diabetes mellitus in which these drugs could prove dangerous the patient would go into hypoglycemia and this hypoglycemia would

Not get corrected beta blockers most importantly decrease the lipolysis increase the vldl and decrease the hdl which are not good science for a patient with hypercholesterolemia the long term administration of beta blockers leads to decreased contractuality of the heart and can make the heart more susceptible to ventricular dilation congestive heart failure

Due to the decreased contractility next important thing to remember is it’s an antagonist so if you’re giving it for a long period of time it’s going to lead to the up regulation of receptors leading to the supersensitivity so if you stop these drugs abruptly the abrupt withdrawal could lead to in general attacks arrhythmias micro infection and hypertension up

Regulation being the important cause behind this the prolonged use of beta blockers also leads to fatigue mental depression and sexual dysfunction let’s know some important drug interactions of beta blockers if you give them with the hepatic maximal enzyme system inhibitors like cyanidine fluoxetine peroxide in or regenerability these drugs are going to inhibit

The breakdown of propranolol or the beta blockers and there’s going to be increased toxicity of the beta blockers whereas if you use them with inducers like rifampin barbiturates and phenytoin is going to induce the breakdown of beta blockers they’ll be metabolized fast and the effect of the beta blocker is going to be less better blockers as anti-atomic agents

Is a very important issue they are class two anti-arrhythmic agents namely propranolol metroprolol sotalolone esmolol are the anti-arithmetic drugs and they are preferred in the management of supraventricular tachycardias and digitalis induced tachy arrhythmias we need to remember an important thing about asmolol which is an ultra shot acting agent it acts very

Fast and is useful for critical arrhythmias like acute arrhythmias in critically ill patients intraoperative and post-operative areas post myocardial infarction arrhythmias and sudden death after ami as well as the arrhythmias associated with cardiac catheterization finally we come to discuss the uses of beta blockers keeping in mind propranolol as a prototype

Drug firstly is useful in hypertension we need to know the three mechanisms by which beta blockers decrease the blood pressure number one they block the beta1 receptors in the heart and decrease the cardiac output number two they block the beta1 receptors in the juxtaglomerular cells of the kidneys leading to decrease in the radiant activity and they also

Act on the central nervous system to decrease the central sympathetic outflow next important use is chronic profile prophylaxis of angina in which the beta blockers increase the exercise tolerance the decrease the oxygen oxygen consumption and the decrease the rate of the heart next you can use better blockers along with alpha blockers rather first give alpha

Blockers produce enough alpha blocker and then start a beta blocker for a patient with theochromocytoma so also you can prevent the myocardial infarction on chronic basis by the use of beta blockers it’s also proven that they’re useful in cases of acute mi it to limit the infarct size in this patient they are especially useful for supraventricular technical

Ideas including atrial fibrillation and flutter av nodal reentry tachycardias and cad cholamine induced arrhythmias as well as the digitalis induced tachyarrhythmias this slide is showing you all the effects of beta blockers which are mostly concerned with the cardiovascular system now we go to the other uses of beta blockers which are equally important and it

Contains thyrotoxic courses for short-term adjunctive therapy beta blockers are extremely useful because they decrease the manifestations of anxiety associated with pyrotoxic horses they are going to control the blood pressure they are going to control the heart rate and they are going to decrease the anxiety problem has got some additional value because it

Can also affect the peripheral conversion of t3 into t4 sympathetic effects and arrhythmias in thyrotoxic forces are going to be controlled by the beta blockers so also because they are decreasing the manifestations of anxiety they are useful in anxiety states just to give an example it could be useful to prevent the stage fright but more important is all the

Anxiety associated disorders you could use beta blockers they are also useful to treat the alcohol withdrawal symptoms and the various drug withdrawal states they are useful to treat essential tremor and familiar tremor they are useful to prevent the tetralogy of phallocyanotic spells they are useful in the chronic prophylaxis of migraine due to the blockage

Of the catecholamine-induced vasodilation in the cerebral vasculature and they are useful in the symptomatic management of hypertrophic subaotic stenosis i especially want you to remember esmolol as an ultrashock acting agent which acts for eight to ten minutes it’s the half-life of esbolog and is used intravenously please don’t forget the arrhythmias associated

With surgery the arrhythmias associated with various diagnostic procedures second important thing to remember is neurolog which is the longest acting beta blocker and his half-life is 24 hours there’s a special use for beta blockers like propranolol and neural they are used to decrease the portal venous pressure and to prevent bleeding and death in patients

With liver cirrhosis and esophageal paralysis so that was a review that was a summary of alpha blockers as well as beat blockers i hope this presentation will be extremely useful to you thank you very much

Transcribed from video