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 Adrenergic drugs

It is a broad class of drugs that bind to adrenergic receptors throughout the body. These receptors include: Alpha 1, Alpha 2, Beta 1, Beta 2, Beta 3

The adrenergic drugs will bind directly to one or more of these receptors to cause different physiological effects.

Some drugs act indirectly on these receptors to cause certain effects.

Adrenergic drugs must be classified based on the specific receptors they bind to.

Direct-acting drugs, which are the main focus of this article, include vasodilators, bronchodilators, and other drugs.

Amphetamine and cocaine its the best Examples of indirect drugs

Main effects that stimulate or activate adrenergic receptors

alpha-1 receptor: smooth muscle contraction, mydriasis

Alpha 2 receptors: mixed effects on smooth muscles

Beta 1 receptors: Increased chronic cardiac and inotropic effects

Beta 2 receptors: the expansion of the airways (bronchodilation) 

Beta 3 receptors: increase lipolysis

adrenergic drug




Classes of adrenergic drugs

1)Adrenergic agonist

A) Direct acting

1) non selective 

That is, it does not distinguish between alpha or beta receptors. It is based on stimulating all receptors, and these drugs are

i) Epinephrine or epinephrine

ii) Epinephrine or epinephrine light

iii) Isoproterenol or Isoprenaline

iv) Dopamine


2) selective

That is, it binds to one of the aforementioned receptors and gives its effect on the region in which it is bound

i) selective beta-1 agonist such as: dobutamine
ii) selective peripheral (D1) agonist such as: fenoldopam
iii) selective alpha-1 agonist such as: phenylephrine, midodrine, naphazoline, tetrahydrozoline, xylometazoline, oxymetazoline
iv) selective alpha-1 agonist such as: clonidine, alpha-methyldopa, apraclonidine, brimonidine, levixidine
v) selective beta-2 agonist, divided into: -
a) Short-acting, such as: metaproterenol or orciprenaline, salbutamol or albuterol, terbutaline
b) Long-acting, such as: formoterol, salmeterol
c)Ultra-Long-acting  such as: indacaterol

 B) Indirect effect

These drugs are
i) amphetamine
ii) dextromethorphan
iii) methamphetamine
iv) methylphenidate
v) Modafinil
vi) Tyramine

C) Mixed effect

These drugs are
i) Ephedrine
ii) Pseudoephedrine


pharmacological action for Adrenergic agonist

1) local effect

vasoconstriction in nose

2) heart (B1) 

positive inotropic , chronotropic and dromotropic

3) blood vessels

i) skin blood vessels

vasoconstriction

ii) skeletal muscle blood vessels

vasodilation

4) lung 

powerful bronchodilation (B2)

5) GIT

relax GIT & genito-urinary muscle 

6) Eye

active mydriasis 
Adrenergic agonist


2)adrenergic antagonists

A) Alpha blockers

It is divided into: -
i) Non-selective blocker such as: phenoxybenzamine, tolazoline, phentolamine
ii) selective alpha1 receptor blockers such as: prazosin, terazosin, doxazosin, alfuzosin, tamsulosin
iii) selective Alpha 2 blockers such as: yohimbine

B) Beta blockers

1) Non-selective blocker such as: propranolol, nadolol, timolol, sotalol
2) selective blocker such as: betaxolol, Esmolol, bisoprolol, nebivolol, metoprolol, atenolol
3) beta-blockers with partial agonist activity such as: acebutolol, pindolol, celiprolol
4) Mixed blocker such as: Labetalol, Carvedilol

pharmacological actin for adrenergic antagonist

1) heart 

negative inotropic & chronotropic & slow SA &VA nodal conduction & decrease cardiac work 

2) lung

bronchoconstriction 

3) Eye 

decrease IOP especially in glaucoma due to decrease aqueous humour formation
adrenergic antagonists





 Note / This information is taken from the following websites: -


2) NCBI

3) Pharma Guide

In the next article, we will talk about each drug in detail about the boring, side effects, and therapeutic effects, and the pharmacokinetic for each medicine

Finally, if you encounter any difficulties or problems, please write in the comments, and do not forget to share this article, so that we can learn more

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