Adrenergic System New

Adrenergic System

Adrenergic System : What is Adrenergic System ?

Adrenergic system means "having to do with adrenaline (epinephrine) or noradrenaline (norepinephrine)".

Uses adrenaline (epinephrine) and noradrenaline (norepinephrine) as neurotransmitters.

Adrenergic receptorThe adrenergic receptors (or adrenoceptors) are a class of G protein-coupled receptors that are targets of the catecholamines, especially norepinephrine (noradrenaline) and epinephrine (adrenaline).

Many cells possess these receptors, and the binding of a catecholamine to the receptor will generally stimulate the sympathetic nervous system. The sympathetic nervous system is responsible for the fight-or-flight response, which includes widening the pupils of the eye, mobilizing energy, and diverting blood flow from non-essential organs to skeletal muscle.Neurotransmission at adrenergic neuronsNeurotransmission at adrenergic neurons closely resembles that described for the cholinergic neurons, except that norepinephrine is the neurotransmitter instead of acetylcholine.

Categories of Adrenergic receptorThere are two main groups of adrenergic receptors, Alpha ( ) and beta ( ) , with several subtypes : receptors have the subtypes1 and 2 receptors have the subtypes 1 and 2

Pharmacological effect of activation of receptors :Alpha 1 ( 1) :Blood vessels : vasoconstriction , increase peripheral resistance and increase blood pressure Eye : Mydriasis (dilatation of pupil)Sphincter smooth muscle : Contraction

Diagram of effect of1 receptors

Pharmacological effect of activation of receptors :Alpha 2 ( 2) :Decrease nor epinephrine release.Decrease insulin release

Pharmacological effect of activation of receptors :Beta 1 ( 1): Heart: increase contractibility and heart rate.Metabolism: lipolysis , increase free fatty acid in blood.Glands: increase rennin secretion from juxtaglomerular.

Diagram of Pharmacological effect of activation of 1 receptors :

Pharmacological effect of activation of receptors :Beta 2 ( 2 ) :Blood vessels: dilatation ( skeletal muscles ,coronary )Smooth muscles: relaxation ( bronchioles, git, urinary bladder and uterus )Metabolism: Glycogenolysis, hyperglycemia, increase output of glycogen

Adrenergic agonist & antagonistAn adrenergic agonist is a drug that stimulates a response from the adrenergic receptors

An Adrenergic antagonist is a pharmaceutical substance that acts to inhibit the action of catecholamines at the adrenergic receptors.

Adrenergic agonist :A- Direct action

Epinephrine (adrenalin) : affect all types of adrenergic receptors.Action:HeartBlood vesselsRespiratory system HyperglycemiaLipolysis


Therapeutic uses of Epinephrine :Asthma: in treatment of acute asthma, after few minutes of Subcutaneous administration greatly improved respiratory exchange is improved. Glaucoma: In ophthalmology, a 2% Epinephrine solution may be used topically to reduce intraocular pressure (IOP) in open-angle glaucoma.Anaphylactic shock: in treatment of type I hypersensitivity reactions.Local anesthetic

Epinephrine Drug


Nor epinephrine (nor adrenalin): is a catecholamine with multiple roles including those as a hormone and a neurotransmitter. It is the hormone and neurotransmitter most responsible for vigilant concentration in contrast to its most chemically similar hormone, dopamine, which is most responsible for cognitive alertness. more effect on receptors.Adrenergic agonist :A- Direct action

Therapeutic uses:Its never used for asthma or in combination with local anesthetics.it's a potent vasoconstrictor and will cause extravasation (discharge of blood from vessel into tissues) along the injection site.


Isoproternol (Isuprel) : is a medication used for the treatment of bradycardia (slow heart rate), heart block, and rarely for asthma. It is a non-selective beta-adrenergic agonist and structurally similar to adrenaline.Adrenergic agonist :A- Direct action

Isoproternol (Isuprel) : act on receptors (no effects)Increase heart rate (1)Lipolysis (1)Pulmonary (2)Glycogenolysis (1)


Dopamine: is a hormone and neurotransmitter of the catecholamine family that plays a number of important roles in the human brain and body. Affects receptor at high dose and receptors at low dose.Dopamine: Affects receptor at high dose and receptors at low dose.Action:CardiovascularRenal and vesceral: dilutes renal and splanchnic arterioles, thus increase blood flow to the kidneys and other viscera.Dopamine DrugDopamine DrugTherapeutic uses:Shock: given by iv infusion (because of short action), stimulate heart by 1 action, enhance renal circulation.


Dobtuamine: is a sympathomimetic drug used in the treatment of heart failure and cardiogenic shock. Its primary mechanism is direct stimulation of 1 receptors of the sympathetic nervous system.


Dobtuamine: affects on 1Action: increase cardiac output and rateTherapeutic uses: in congestive heart failure, increase cardiac output without increase cardiac rate


Phenylphrine: is a selective 1-adrenergic receptor agonist of the phenethylamine class used primarily as a decongestant, as an agent to dilate the pupil, and to increase blood pressure.


Methoxamine: is an 1-adrenergic receptor agonist, similar in structure to phenylephrine. The drug induces vasoconstriction of skin and splanchnic blood vessels, thereby increasing peripheral vascular resistance and raising mean arterial blood pressure. Because of its hypertensive effects.


Clonidine: (trade names Catapres, Kapvay, Nexiclon, Clophelin, and others) is a sympatholytic medication used to treat high blood pressure, attention-deficit/hyperactivity disorder, anxiety disorders, migraine, menopausal flushing, diarrhea, and certain pain conditions. It is classified as a centrally acting 2 adrenergic agonist .

Clonidine


Metaproterenol (2): (trade name: Alupent , Metaprel ) is a bronchodilator used in the treatment of asthma. metaproterenol is a moderately selective beta2-adrenergic receptor agonist that stimulates receptors of the smooth muscle in the lungs, uterus, and vasculature supplying skeletal muscle, with minimal or no effect on alpha-adrenergic receptors.Metaproterenol

Adrenergic agonist :B- Indirect action

Amphetamine: this drug has marked CNS stimulation, increase BP , the CNS effects is abused, but it is useful in depression, hyperactivity in children, sleeping sickness (narcolepsy) and appetite control (treatment of obesity)


Tyramine Mechanism of action for Amphetamine and Tyramine is mixed action:Cause release of stored catecholamine.Direct action on adrenergic receptors.


Ephedrine: is a sympathomimetic amine commonly used as a stimulant, concentration aid, decongestant, appetite suppressant, and to treat hypotension associated with anaesthesia. Ephedrine is similar in molecular structure to the important neurotransmitter epinephrine (adrenaline). It works mainly by increasing the activity of norepinephrine (noradrenaline) on adrenergic receptors.Adrenergic agonist :B- Indirect action

Cocaine: is obtained from the leaves of the coca plant. It is a stimulant, an appetite suppressant, and a nonspecific voltage gated sodium channel blocker, which in turn causes it to produce anaesthesia at low doses. Biologically, cocaine acts as a serotoninnorepinephrinedopamine reuptake inhibitor.

Adrenergic AntagonistA- Direct antagonist:

Alpha Adrenergic blocking agents:Phenoxybenzamine: (marketed under the trade name Dibenzyline) is a non-selective, irreversible alpha antagonist.

Phenoxybenzamine :

Therapeutic uses:It is used in the treatment of hypertension, and specifically that caused by pheochromocytoma. It has a slower onset and a longer lasting effect compared with other alpha blockers.It was also the first alpha blocker to be used for treatment of benign prostatic hyperplasia, although it is currently seldom used for that indication due to unfavourable side effects.It has been used in the treatment of hypoplastic left heart syndrome.


Phentolamine: (Regitine) is a reversible nonselective alpha-adrenergic antagonist. Mechanism : Its primary action is vasodilation due to 1 blockade.It also can lead to reflex tachycardia because of hypotension and 2 inhibition, which increases sympathetic tone.

PhentolamineUses:The primary application for phentolamine is for the control of hypertensive emergencies, most notably due to pheochromocytoma.It also has usefulness in the treatment of cocaine-induced cardiovascular complicationsPhentolamine has recently been introduced in the dental field as a local anesthetic reversal agent.


Parzosin: ( trade names Minipress, Vasoflex, Pressin and Hypovase) is a sympatholytic drug used to treat high blood pressure and anxiety, PTSD, and panic disorder. It is an alpha-adrenergic blocker that is specific for the alpha-1 receptors. These receptors are found on vascular smooth muscle, where they are responsible for the vasoconstrictive action of norepinephrine.

Parzosin


doxasin: (Trade name: Cardura and Carduran) is an 1-selective alpha blocker used to treat high blood pressure and urinary retention associated with benign prostatic hyperplasia (BPH).

Doxasin or DoxazosinIt is an alpha-1 adrenergic receptor blocker that inhibits the binding of norepinephrine (released from sympathetic nerve terminals) to the alpha-1 receptors on the membrane of vascular smooth muscle cells. The primary effect of this inhibition is relaxed vascular smooth muscle tone (vasodilation), which decreases peripheral vascular resistance, leading to decreased blood pressure.

Doxasin or Doxazosin


2. Beta Adrenergic blocking agents:Propranolol (Inderal): -blockersTherapeutic uses are:Hypertension Hyperthyroidism: prevent cardiac arrhythmiaGlaucoma: chronic treatment (timolol is perfect)Migraine: by blocking catecholamines induce vasodilation in the brain vessels.Angina pectoris: decrease demand for oxygen.Inferction

Propranolol (Inderal) Drug


2. Beta Adrenergic blocking agents:

Timolol: is a non-selectivebeta-adrenergic receptor antagonist indicated for treating glaucoma, hypertensionand migraine headache.


2. Beta Adrenergic blocking agents:Nadolol: (Corgard) is a non-selective beta blocker used in the treatment of high blood pressure and chest pain. Additionally, it is often prescribed in the treatment of atrial fibrillation, migraine headaches, and complications of cirrhosis.Nadolol: (Corgard)2. Beta Adrenergic blocking agents:


2. Beta Adrenergic blocking agents:Atenolol: is a selective 1 receptor antagonist, a drug belonging to the group of beta blockers (sometimes written -blockers), a class of drugs used primarily in cardiovascular diseases. Introduced in 1976, atenolol was developed as a replacement for propranolol in the treatment of hypertension. It works by slowing down the heart and reducing its workload. Unlike propranolol, atenolol does not pass through the bloodbrain barrier thus avoiding various central nervous system side effects.


2. Beta Adrenergic blocking agents:Atenolol: is commonly used as antihypertensive drug in IRAQ(25mg,50mg and 100mg)


2. Beta Adrenergic blocking agents:Esmolol: (trade name Brevibloc) is a cardioselective beta1 receptor blocker with rapid onset, a very short duration of action. Esmolol decreases the force and rate of heart contractions by blocking beta-adrenergic receptors of the sympathetic nervous system, which are found in the heart and other organs of the body. Esmolol prevents the action of two naturally occurring substances: epinephrine and norepinephrine.

Esmolol


2. Beta Adrenergic blocking agents:Pindolol: (trade name: Visken, Betapindol, Blockin L, Blocklin L, Calvisken, Cardilate, Decreten, Durapindol, Glauco-Visken, Pectobloc, Pinbetol, Prindolol, Pynastin) is a nonselective beta blocker with partial beta-adrenergic receptor agonist activity. This means that pindolol, particularly in high doses, exerts effects like epinephrine or isoprenaline (increased pulse rate, increased blood pressure, bronchodilation), but these effects are limited.

Pindolol


2. Beta Adrenergic blocking agents:Acebutolol: (trade names Sectral, Prent) is a beta blocker for thetreatment of hypertensionand arrhythmias.


2. Beta Adrenergic blocking agents:Labetalol: (trade names Normodyne and Trandate) is a mixed alpha/beta adrenergic antagonist that is used to treat high blood pressure.

Labetalol (Trandate)

Adrenergic AntagonistB- Indirect antagonist:

Reseprine: is antipsychotic and antihypertensive drug that has been used for the control of high blood pressure and for the relief of psychotic symptoms, although because of the development of better drugs for these purposes and because of its numerous side-effects, it is rarely used today.Guanethidine: is an antihypertensive drug that reduces the release of catecholamines, such as norepinephrine.

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Adrenergic System New