Adrenergic Drugs Flashcards by Amy woodstock

How are the Alpha Adrenoreceptors divided?

Alpha1 and Alpha 2 receptors…. are further divided into Alpha1A, Alpha1B, Alpha1C, and Alpha1D and into Alpha2A, Alpha2B, Alpha2C – extended classification is necessary for understanding selectivity of some drugs.

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What are the two families of adrenergic receptors?

Alpha Adrenoreceptors and Beta Adrenoreceptors

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What are the types of Adrenoreceptors?

Alpha1 and Alpha 2

Beta 1 and Beta 2

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What are the major effects mediated by Alpha 1 adrenoreceptors?

Vasoconstriction
Increased peripheral resistance
Increased blood pressure
Mydriasis
Increased closure of internal sphincter of the bladder

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What are the major effects of Alpha 2 Adrenoreceptors?

Inhibition of norepinephrine release
Inhibition of acetylcholine release
Inhibition of insulin release

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What are the major effects of Beta 1 adrenoreceptors?

Tachycardia
Increased lypolysis
Increase myocardial contractility
Increased release of renin

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What are the major effects mediated by Beta 2 adrenoreceptors?

Vasodilation 
Slightly decreased peripheral resistance
Broncodilation
Increased muscle and liver glycogenolysis
Increased release of glucagon
Relaxed uterine smooth muscle

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What are the 3 classifications of Adrenergic Agonists?

Direct Acting Adrenergic Agonist
Indirect Acting Adrenergic Agonist
Mixed Action Adrenergic Agonist

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What is the MOA of Direct Acting Adrenergic Agonist?

These drugs directly act on Alpha and Beta receptors producing similar effects to those that occur following stimulation of sympathetic nerves or release of the hormone epinephrine from the adrenal medulla.
2 types: chateholemines and noncatecholemines

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What are the 2 types of direct acting adrenergic agonists?

Catecholemines and Noncatecholemines

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What are typical direct acting catecholemines?

**Epinephrine (Adrenaline) acts on Alpha1, Alpha2, Beta1 and Beta2 - used for intense asthma and, anaphylactic shock, etc…
**Dobutamine (Debutrex) acts on Beta1 - drug of choice to stimulate heart
**Dopamine (Intropin) acts on Alpha1 & Beta1 - used to treat shock

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Direct Acting Adrenergic Agonist: Catecholemine –> Epineprine

Epinephrine (Adrenaline)
Alpha1, Alpha2, Beta1, Beta2
used in intense asthma, anaphylactic shock, etc

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Direct Acting Adrenergic Agonist: Catecholamines –> Dobutamine

Dobutamine (Debutrex)
Beta1
Drug of choice to stimulate heart

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Direct Acting Adrenergic Agonist: Catecholamines –> Dopamine

Dopamine (Intropin)
Alpha1 & Beta1
Used to treat shock

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What are typical Direct Acting Noncatecholemines?

**Phenylephrine (Neo-synephrine) - Alpha1 –>causes intense vasoconstriction
**Terbutaline (Bethrine) - Beta1 —> used as bronchodilator
**Albuterol (Ventolin) - Beta2 –> used as a bronchodilator
**Salmeterol (Serevent) - Beta2 –> long acting bronchodilator

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Direct Acting Adrenergic Agonist: Noncatecholamines –> Phenylephrine

Phenylephrine (Neo-synephrine)
Alpha1
Uses: causes intense vasoconstriction

Direct Acting Adrenergic Agonist: Noncatecholamines –> Terbutaline

Terbutaline (Brethine)
Beta2
Used a bronchodilator

Direct Acting Adrenergic Agonist: Noncatecholamines –> Salmeterol

Salmeterol (Serevent)
Beta2
Used as a long acting bronchodilator

What is the MOA of Indirect Acting Adrenergic Agonist?

They cause norepinephrine release from presynaptic terminals or inhibit the uptake of nor-epinephrine.

**Amphetamine –> has CNS stimulatory effects. Uses: narcolepsy, ADHD, appetite control
**Methylpheidate (Ritalin) –>Same as amphetamine… narcolepsy, ADHD, appetite control

Indirect Acting Adrenergic Agonist: Amphetamine

Amphetamine - has CNS stimulatory effects

Uses - narcolepsy, ADHD, appetite control

Indirect Acting Adrenergic Agonist: Methylphenidate

Methylphenidate (Ritalin): has CNS stimulatory effects

Uses: Narcolepsy, ADHD, appetite control

Indirect Acting Adrenergic Agonist: What happens if a patient taking MAO-inhibitors eat lots of cheese? Explain

Tyramine is found in fermented food. Tyramine is oxidized by MAO (Monoamine oxidase). If a patient taking MAO-inhibitors eats cheese, tyramine of cheese can not be oxidized. Tyramine enters nerve Terminal and displaces stored norepinephrine, thereby causing hypertensive crisis. Patient can carry 25mg tablets of chlorpromazine and as soon as signs of such reaction occur, take tablets and head to ER.

What is the MOA of Mixed Action Adrenergic Agonists?

These drugs induce the release of norepinephrine from presynaptic terminals; also directly stimulates both Alpha and Beta receptors on the postsynaptic membrane.
***Epinephrine - asthma, nasal decongestant

What are adrenergic antagonists?

These drugs bind to adrenergic receptors and prevent their activation by endogenous epinephrine and norepinephrine

How to classify adrenergic antagonists?

Alpha-adrenergic blocking agents --> these drugs block Alpha receptors Beta-adrenergic blocking agents --> all clinically available Beta blockers are competitive antagonists. Non-selective Beta blockers act at both Beta1 and Beta2, whereas cardioselective Beta antagonists primarily block Beta1 receptors.

What are the 4 types of Alpha adrenergic blocking agents?

1. Non-selective Alpha Blockers (Alpha1 and Alpha2) 2. Alpha1 Blockers 3. Alpha1 A blockers 4. Alpha2 Agonists

Alpha Adrenergic Blocking Agents: | What is MOA of Non-selective Alpha Blockers (Alpha1 & Alpha2 blockers)?

These drugs block both Alpha adrenergic receptors causing vasodilation and lowering blood. ***Phenoxybenzamine (Dibenzyline)

Adrenergic Antagonist: Non-selective Alpha Blockers --> Phenoxybenzamine

Phenoxybenzamine (Dibenzyline) - vasodilation and lowering of blood pressure

Alpha Adrenergic Antagonist: Alpha1 Blocker --> Doxazosin

Doxazosin (cardura) - used in tx of hypertension. these drugs can cause orthostatic hypotension

Adrenergic Antagonists: Alpha1 A blockers --> Tamsulosin

Tamsulosin (Flomax) - relaxes smooth muscle in the urinary bladder neck and prostate. Thus improving urine flow in Benign Prostate Hyperplasia

Adrenergic Antagonist: Alpha2 agonists --> Clonidine

Clonidine (catapress) Inhibits both sympathetic output from the brain and release of norepinephrine from nerve terminals. Thus they reduce blood pressure. Use: hypertension

What is MOA of Beta-adrenergic blocking agents?

``` All the clinically available B-Blockers are competitive antagonists. Nonselective Beta-blockers act as both Beta1 and Beta2 receptors, whereas cardioselective B-antagonists primarily block B1 receptors. 3 types: 1. Non-selective (B1 and B2) 2. B1 selective Blockers 3. Mixed Alpha and Beta Blockers ```

Adrenergic Antagonists: Beta-adrenergic blocking agents: Non-selective B1 and B2

All are used for hypertension. Propranolol is also effective in treating angina, cardiac arrhythmia, myocardial infarction, congestive heart failure, hyperthyroidism, and glaucoma as well as serving n the prophylaxis of migraine headaches ***Propranolol ***Sotalol drugs contraindicated for asthma

Adrenergic Antagonists: Beta-adrenergic blocking agents: Beta1 - Selective Blockers

* **Metoprolol (Lopressor): hypertension, myocardial infarction, angina pectoris * **Atenolol (Tenormin)

Adrenergic Antagonists: Beta-adrenergic blocking agents: Mixed Alpha and Beta blockers

* **Labetalol (Normodyne): Alpha1, Beta1 and Beta2 Blockers * **Carvedilol (Coreg): Alpha1, Beta1, and Beta2 blockers - These drugs decrease BP without reflex tachycardia. Used in the treatment of hypertension

What are the cautions needed to take when a patient with type 1 Diabetes is to be given Propranolol and why?

Beta Blockade leads to decreased glycogenolysis and decreased Glucagon secretion. Therefore if a patient with Type 1 diabetes is to be given Propranolol, very careful monitoring of blood glucose is essential, because pronounced hypoglycemia may occur after insulin injection. Also reflex increase in heart rate that occurs in response to hypoglycemia is also blocked by Beta blockers.

What are the risks of withdrawing Beta Blockers? How can we avoid that?

Treatment with Beta Blockers must never be stopped quickly because of the risk of precipitating cardiac arrhythmias, which may be severe. The Beta blockers must be tapered off gradually for at least a few weeks. Long-term treatment with a Beta antagonist leads to up-regulation of the Beta receptor. On suspension of therapy, the increased receptors can worsen angina or hypertension.