Adrenergic Agonist/Antagonists

Question 1

Direct Acting Agonists (3)

Answer 1

1. Epinephrine
2. Norepinephrine
3. Dopamine

Endogenous Catecheolamines

Question 2

Epinephrine Effects

(7)

Answer 2

1. Acts on both alpha and beta receptors
2. Increases HR/Contractile force (b-1 effect)-increase O2 consuption by the heart
3. Increases renin release (b-1)
4. Constricts arterioles in skin and viscera (a-1)
5. Dilates BV of skeletal muscle (b-2)
6. Relaxes bronchiol smooth muscle (b-2)
7. Increases glycogenolysis/lipolysis (b1,b2)

Question 3

What happens when giving a pt a low dose of epi?

Answer 3

1. PVR decreases d/t b-2 receptors are more sensitive to epi than a-1 receptors
2. Diastolic pressure falls
3. Systolic pressure increases d/t increases cardiac contractility (b-1)
4. HR increases (b-1)

No increase in mean BP so the baroreceptor reflex does not kick in

Question 4

What happens when giving a high dose of epi?

Uses as well

Answer 4

1. Increase in ventricular contraction (b-1)
2. Increase in HR (b-1)-opposed by the baroreceptor reflex
3. Vasoconstriction (a-1)

Uses: anaphylactic shock, cardiac arrest, asthmatic attacks

Question 5

Norepinephrine Effects

Answer 5

Alpha 1,2 and Beta 1
1. Peripheral vasoconstriction (a-1)
2. Increase cardiac contractility (b-1)
3. Increase in BP stimulates baroreceptors leading to reflex bradycardia

Tx: shock-increase BP

Question 6

Isproterenol

Answer 6

Non-selective beta adrenergic agonist
1. Activates b-1/2
2. Increases HR, contractility, and CO (b-1)
3. Dilates arterioles of skeletal muscle (b-2)
4. Diastolic pressure decrease-systolic remains unchanged (could go up)
5. Bronchodilation (b-2)
6. Used in emergencies to stimulate HR in pt’s with HB and bradycardia

Question 7

Dobutamine

Answer 7

Beta-1 Selective Adrenergic Agonist
1. Potent inotrope-mild chronotropic effects
2. Less increase in HR and decrease in PVR than isoproterenol
3. Mild vasodilation
4. Increase in cardiac O2 consumption-stress echocardiogram

Management of Acute HF, cardiogenic shock

Question 8

Albuterol

Answer 8

Beta-2 Adrenergic Agonist
1. Causes bronchodilation
2. Used with ICS in asthma
3. DOC for acute asthma attacks

Question 9

Salmeterol/Formoterol

Answer 9

Beta-2 Adrenergic Agonist
Prolonged duration compared to albuterol

Used in asthma

Question 10

Mirabegron

Answer 10

Beta-3 adrenergic agonist-detrusor muscle relaxation and increases bladder capacity

Tx: Overactive bladder, urinary incontinence

Moderate CYP2D6 inhibitor

Question 11

Adverse effects of Mirabegron

Answer 11

1. Increase BP
2. Increased UTI
3. Headache

Question 12

Phenylephrine

Answer 12

Alpha-1 adrenergic agonist
1. Vasoconstriction

Uses:
1. Nasal decongestant. Given PO/topical
2. Mydriasis
3. Tx of hypotension from vasodilation in anesthesia

NO CYCLOPLEGIA

Question 13

Clonidine

Answer 13

Alpha-2 Adrenergic Agonist
CENTRALLY ACTING ANTIHYPERTENSIVE
1. Activates central presnypatic alpha-2 adrenoceptors which reduces sympathetic outflow thus reducing BP

Question 14

Adverse effects of Clonidine

Answer 14

1. Lethargy
2. Sedation
3. Xerostomia

Question 15

Methyldopa

Answer 15

Activates central alpha 2 adrenoceptors
* Drug of choice for Tx of hypertension in pregnancy

Question 16

Methylphenidate

Answer 16

Unknown mechanism

Increases Norepi and dopamine reuptake inhibitor

Tx: ADHD in kids

Question 17

Atomoxetine

Answer 17

Selective inhibitor of NET

Tx: ADHD in kids

Question 18

Modafinil

Answer 18

Psychostimulant

Inhibits norepinephrine and dopamine transporters

Tx: Narcolepsy

Question 19

Adverse effects of Methyldopa

(3)

Answer 19

1. Sedation
2. Impaired mental concentration
3. Xerostomia

Question 20

Brimonidine

Answer 20

Highly selective alpha 2 agonist

Tx: lower intraocular pressure in glaucoma (reduces aqueous humor production and increase outflow)

Question 21

Amphetamine

Indirect Acting Adrenergic Agonist- RELEASING AGENT

Answer 21

Causes norepinephrine release by reversing monoamine transporters

Uses: ADHD, Narcolepsy

CNS stimulatory action
Can increase BP, stimulatory effects on heart

Question 23

Cocaine

Indirect Acting Adrenergic Agonist-UPTAKE INHIBITOR

Answer 23

Monoamines accumulate in synaptic space-potentiation and prolongation of their central and peripheral actions

Blocks voltage-activated sodium channels

Sympathetic effects like tachycardia, HTN, peripheral vasoconstriction, pupil dilation

*Most potent at blocking DAT (dopamine transporter)-higher concentrations block SERT and NET

SERT=5-HT transporter
NET=Norepi transporter

Question 24

Tyramine

Indirect Acting Adrenergic Agonist- RELEASING AGENT

Answer 24

Found in fermented foods-normally oxidized by MAO.

• Causes release of catecholamines by reversal of NET (Norepi transporter)

If taken w/ MAO-Massive Vasopressive effects

Question 25

Ephedrine | Mixed Acting Adrenergic Agonist

Answer 25

Used as a pressor agent during **spinal anaesthesia** Tx: Adjunct therapy in **myasthenia gravis** Not a catecholamine but penetrates CNS

Question 26

Pseudoephedrine | Sudafed

Answer 26

**Mixed Acting Adrenergic Agonists** -Nasal decongestant

Question 27

Phenoxybenzamine

Answer 27

**Non-selective alpha Adrenergic Blocker** 1. **Irreversible antagonist** 2. Not good for HTN Uses: Prior to surgery for **pheochromocytoma** or for management of inoperable tumors

Question 28

Phentolamine

Answer 28

**Non-Selective Alpha Adrenergic Blocker** 1. Reversibly blocks alpha 1/2 receptors Uses: 1. Dx of/management of **pheochromocytoma** (phentolamine blocking test= Decrease in BP = pheochromocytoma) 2. Prevention of dermal necrosis aftra extravasation of norepinephrine 3. **HTN crisis** d/t stimulate OD

Question 29

Epinephrine Reversal

Answer 29

Alpha adrenergic blockers reverse epinephrine effect but vasodilation of Beta-2 receptors not blocked. **Systemic BP decreases** in response to epi given in the presence of phenoxybenzamine

Question 30

Prazosin, Terazosin, Doxazosin

Answer 30

**Selective blocker of Alpha-1 adrenergic receptors** Uses: 1. HTN (not drugs of choice) 2. **BPH**-drug of choice for symptom relief-relaxes smooth muscle 3. First dose can have exaggerated hypotensive response so small first dose (1/4, 1/3) for first three meds | Prazosin=prototype

Question 31

Tamsulosin

Answer 31

Treatment for **Benign Prostatic Hyperplasia** Selective Alpha-1A receptor (predominates in GU smooth muscle). * Minimal effect on BP * Less likely to cause orthostatic hypotension

Question 32

Propranolol, Nadolol, Timolol

Answer 32

**Beta Adrenergic Blockers** CVS effects: slow HR and decrease myocardial contractility Respiratory: **contraindicated for pts with asthma** Metabolic: decrease glycogenolysis, glucagon secretion | Propranolol=prototype

Question 33

Atenolol/Metoprolol/Esmolol

Answer 33

**Selective Beta-1 Adrenergic Blockers** 1. **impaired pulmonary** fx 2. **diabetic** pts Esmolol: **ultra short half life**, used for rapid control of ventricular rate

Question 34

Pindolol

Answer 34

**Partial beta-Agonist** Preferred in individuals w/ diminished cardiac reserve or a propensity to bradycardia

Question 35

Labetalol/Carvedilol

Answer 35

**Alpha-1, Beta-selective Blockers** *Labetolol*: substantially **more potent b-antagonist** than alpha. (Competitive) *Carvedilol*: Antioxidant properties. Used for HTN/**CHF**

Question 36

Timolol

Answer 36

Tx for **glaucoma**-diminish intraocular pressure

Question 37

Beta blocker uses (10)

Answer 37

1. HTN 2. Glaucoma (timolol) 3. Migraine prophylaxis 4. Hyperthyroidism-blunt sympathetic stimulation 5. Angina-chronic management 6. A Fib-control ventricular rate 7. Myocardial infaction-protective effect 8. Prevention of bleeding from esophageal varices 9. Performance Anxiety 10. Essential Tremor

Question 38

Beta-blocker adverse effects | Hypoglycemia

Answer 38

Nonselective beta blockers impaire recovery of hypoglycemia d/t **blockade of beta-2 receptors in liver** | Also mask tachycardia seen in hypoglycemia (early warning sign)

Question 39

Beta blocker adverse effect | Lipid Metabolism

Answer 39

Inhibit release of free fatty acids from adipose tissue 1. Increase TAGs 2. REduce HDL | Both negative impact

Question 40

Can you withdraw from beta blockers abruptly?

Answer 40

No-should be taper to avoid tachycardia, htn, ischemia (rebound effect d/t increased receptor count)

Question 41

Methyltyrosine (Metyrosine)

Answer 41

Competitive inhibitor of tyrosine hydroxylase (Inhibit norepi **synthesis**) 1. Management of malignant pheochromocytoma 2. Preop preparations for pheochromocytoma

Question 42

Reserpine

Answer 42

**Irreversibly blocks VMAT**-vesicles that store norepi/dopamine 1. Gradual decrease in BP and HR 2. Treated HTN in the past

Question 43

Valbenazine

Answer 43

**Reversible inhibitors of VMAT** Tx of **tardive dyskinesia**

Question 44

Tetrabenazine

Answer 44

**Reversible inhibitors of VMAT** Tx of chorea in **Huntington's Disease**

Question 45

Contraction of the pupillary dilator (radial) in the iris has what function and receptor?

Answer 45

**Mydriasis** Alpha 1 receptor

Question 46

Contraction of the pupillary constrictor (sphincter) muscle in the iris causes has what function and receptor?

Answer 46

**Miosis** M3 receptor

Question 47

Contraction of the ciliary muscle has what function? | And receptor

Answer 47

Adapts to short range focus (M3)

Question 48

What is the function of ciliary epithelium?

Answer 48

Produce aqueous humour Receptors: Beta2, alpha2, D1-3, FP (prostaglandins)

Question 49

Latanoprost

Answer 49

Activates FP receptors to increase uveoscleral outflow decreasing intraocular pressure | FP=prostaglandin

Question 50

Acetazolamide, dorzolamide

Answer 50

Inhibition of carbonic anyhdrase reduces formation of aqueous humor thus decreasing intraocular pressure

Question 51

Overview table of ocular hypotensive drugs

Answer 51

Question 52

Common Autonomic Adverse Effects | Muscarinic agonists, AChE inhib, Antimuscarinics, Stimulants

Answer 52