Drug facts General

Selectivity of Beta blockers



Beta blockers prevent catecholamines ( Epinephrine & Norepinephrine ) from binding to beta receptors.

Mainly , 3 types of beta receptors have been  internationally  identified :  β1 , β2 , β3

” Beta receptors will be illustrated in other coming posts  “


~ First generation of β blockers ~


Non-selective = blocks all β receptors (β1, β2 and β3)


notice the old man in the toon ↑

Mr . Propranolol needs to change his glasses ! , he can read the large β Letters but he cant get a clear vision of their numbers  :blink: ” Non selective “

Hint : Propranolol was the first beta blocker ever to be introduced into therapy in 1965.

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~ Second generation β blockers ~


High selectivity for β1 receptors


notice the business man in the toon ↑

Mr. Atenolol is a very hardworking man .. He focuses all the time on his One and only target  :cool: ( β1 selective )

and since β1 is mainly found in the heart, drugs of 2nd generation are often referred to as :

” cardioselective beta-adrenergic blockers “

Mmmm … i think i should have drawn a heart on Mr. atenolol’s tuxedo :whistle:

.



Tip

Beta blockers are used to reduce High blood pressure by lowering the cardiac output ,

but Propranolol is contraindicated in case of asthmatic hypertensive patients because it blindly blocks all β Receptors including β2 ( non selective )

blocking β2 receptor causes bronchospasm which can be very sever in asthmatic patients :dizzy:

so , in case of hypertensive patients with asthma , the Beta blocker of choice is Atenolol ( selective to β1 only & has nothing to do with β2 )


========



~ Third generation β-blockers ~


Non-selective = blocks all β receptors (β1, β2 and β3)

+

α1 blocker too

” Extra Vasodilation effect :happy: “


Back to the toon , notice the young man with a cap ↑

although Mr. carvidilol is young but he is far from the  Flying Betas so he cant recognize their types ( Non selective )

You probably wonder what’s that thing in his mouth , and  No it’s not a cigarette ..

Mr. Carvidilol likes to blow red cylindrical Gum .. this reminds you of something ?

.

.

.

Yes >> Blood vessels :wink:

( Carvidilol blows Blood vessels > vasodilation effect )







—–

Sources :

– RANG & DALE’s , Pharmacology

– Goodman & Gilman’s , The pharmacological Basis of Therapeutics

– Clinical pharmacology made incredibly easy

– Color Atlas of Pharmacology


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Dina El- Shishtawy
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Go on Darling :heart: :heart:

bgd WooooW

yaret te3mely manhag el pharma kolo keda :cheerful: :cheerful:

Pharmacist
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Thank you for your great article !

I’d like to ask , If the dose of selective B1 blocker increased ( Ex: atenolol ) , does this lead to blocking of B2 receptors ?

Mahmoud
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i cant find words to thank you gor this website and the great effort you exirt …..i konw about it just now and from now i think i will not leave it ,but i ask you for some thing ….i’ll be greatfull if u provided us with thw links of the sources if they are web sitess….. thank you alot :smile:

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