Cholinergic and Adrenergic drugs

Question 1

Phenoxybenzamine

Answer 1

Irreversible a1 and a2 blocker.

Useful for Renauds syndrome

Question 2

Epinephrine

Answer 2

More potent at B2 than a1

Used for

• Bronchial asthma
• Anaphylactic shock
• Infiltration with local anesthetics for vasoconstriction to keep anesthetic local

Side effects: arrhythmias

Question 3

Norepinephrine

Answer 3

Very weak at b2 receptors

IV infusion to maintain BP during spinal anesthesia or hypotensive shock

Question 4

Isopropterenol

Answer 4

Potent at all b receptors, no alpha effects

Question 5

Dopamine

Answer 5

Potent at D receptors

D1: Vasodilates renal BV, increases blood flow to the kidneys

D2: modulates NT release at nerve endings

Heart- mild increase in rate and force (partial agonist B1 and increases release of NE)
Blood vessels- high doses cause vasoconstriction and increased BP. In the situation of shock, this is an undesirable effect because decrease tissue perfusion

Question 6

Dobutamine (Dobutrex)

Answer 6

B1 selective agonist

Clinical use: cardiogenic shock, MI, CHF

Adverse effects: may increase size of infarct.
Increases the work/O2 requirement

Question 7

Phenylephrine

Answer 7

Non-catecholamine
A1 agonist prototype

Maintains BP in hypotensive states.
Nasal decongestant- vasoconstriction to decrease edema

• Vasoconstricition
• Increase peripheral resistance; increase BP
• Increased BP causes reflex bradycardia

Question 8

Albuterol

Answer 8

Non-catechomamine
B2 agonist prototype (10x more potent at B2 than B1)

Main side effects: muscle tremors and tachycardia

Note: also salmeterol and formoterol- long acting bronchodilator for night time asthma

Question 9

Amphetamines

Answer 9

Non-catechomamine
Indirect acting
Release NE from nerve terminals and inhibit NE reuptake by competition.

Crosses BBB
Used for: narcolepsy, AHDH, obesity

Question 10

Pseudoephedrine

Answer 10

Mixed acting on alpha and beta.
Used for nasal decongestants

Access restricted. Used illegally to synthesize methamphetamine.

Question 11

Phentolamine

Answer 11

Prototype reversible a1 and a2 blocker

Used for clonidine withdrawal

Question 12

Prazosin

Answer 12

Selective a1 blocker
Generally reflex tachycardia is less prevalent than with non-selective alpha blockers

When 1st administered, may see syncope and orthostatic hypertension
Used for hypertension and BPH

Question 13

Tamsulosin

Answer 13

Selective a1A blocker

Used for BPH

Question 14

Propanolol

Answer 14

Nonselective beta blocker

decreases O2 demand and work on the heart (angina pectoralis)

Contraindicated in asthmatics and diabetics

• Blocks bronchodilation
• Masks signs of hypoglycemia

Is well absorbed following oral administration. Up to 75% may be inactivated by first pass metabolism.

Question 15

Atenolol

Answer 15

B1 selective = cardioselective

Lessens risk of bronchospasm.

Question 16

Metropolol

Answer 16

B1 selective= cardioselective

Lessens risk of bronchospasm but still contraindicated in asthmatics.

Question 17

esmolol

Answer 17

B1 selective = cardioselective
Very rapid onset and short duration

Used as IV infusion for peri-operative tachycardia and hypertension

Question 18

Labetalol

Answer 18

Selective a1 blocker
also a non selective beta blocker
- Partial agonist at B2

vasodilating

Question 19

Carvediol

Answer 19

Nonselective B and a blocker
Lipid soluble and has antioxidant properties
vasodilating

Reduce mortality in CHF patients

Question 20

Reserpine

Answer 20

Sympatholytic agent

Depletes NE by blocking vesicular transporter
Decreases CO but is a last choice drug

Question 21

Clonidine

Answer 21

a2 agonist- sympatholytic agent

Activation of a2 in the brain decreases sympathetic outflow in the periphery and decreases sympathetic effects

Sudden withdrawal causes hypertensive crisis

Question 22

Methyldopa

Answer 22

Sympatholytic agent
Compare with clonidine.
Acts like NE in disguise.

Stored in vesicles instead of NE. Released and acts a centrally acting a2 agonist.

Decreases central sympathetic outflow and decreases blood pressure

DOC for treating HTN in pregnant females.

Question 23

“zosin”

Answer 23

a1 blocker

Question 24

Pindolol

Answer 24

Beta blocker that is also a partial agonist

Question 25

Carteolol

Answer 25

beta blocker that is also a partial agonist

Question 26

Sotalol

Answer 26

Intrinsic sympathomimetic activity –> partial agonist

Question 27

Clinical uses of beta blockers

Answer 27

• Hypertension: produces slow (weeks) decrease in peripheral resistance
• Ischemic heart disease
• MI and post-MI prophylaxis
• Congestive heart failure
• Arrhythmias

Question 28

Thyrotoxicosis

Answer 28

Hyperthyroid pts have increased beta receptor sensitivity

Beta blockers reduces sensitivity of myocardium to adrenergic stimulation in hyperthyroid pts

Question 29

beta blocker effect on exercise tolerance

Answer 29

beta blockers blunt the increase in HR and contractility that normally occurs with exercise

CO is less affected because stroke volume is increased

beta blockers decrease work capacity

increased catecholamines during exercise or stress increases the work of the heart and myocardial demand

Question 30

Myocardial oxygen consumption

Answer 30

beta blockers decrease myocardial oxygen demand

Question 31

Effects on plasma renin

Answer 31

Catecholamines stimulate B1 receptors in kidney juxtoglomerular apparatus to increase release of renin
- Beta blockers block this increase in renin

BP is decreased in most pts with elevated renin

Question 32

betaxolol

Answer 32

B1 selective vasodilating beta blocker

Question 33

sudden withdrawal of beta blockers

Answer 33

Rebound HTN
Anginal attack
Possibly MI

Beta receptor synthesis is increased by beta blocker use. Ex of receptor up-regulation, supersensitivity

Question 34

a2 receptor agonists

Answer 34

centrally acting antihypertensive agents

• Control (inhibit) sympathetic outflow to periphery
• Decrease sympathetic tone