Agonist And Antagonists Of Cholinergic And Adrenergic

Question 1

Effects of small and large doses of acetylcholine

Answer 1

Small = Decrease BP, reflex tachycardia (M3 effect)

Large =Decrease BP (M3), bradycardia (M2)

Blocking muscarinic antagonists (Ex: Atrophine)

-large doses = nicotinic effects = vasoconstriction and increase in BP

Question 2

Cholinegic Agonists:

Direct Acting drugs (Choline esters)

Answer 2

-All muscarinic agonists

Acetylcholine:

• Nicotinic agonist
• Uses: Obtains meosis for lens in cataract surgery

Methacholine
-Uses: Diagnosis of bronchial airway hyper-reactivity

Bethanechol
-Uses: Post-operative urinary retention/bladder

Question 3

Cholinergic Agonists:

Direct acting drugs (Natural Alkaloids)

Answer 3

Pilocarpine:

• Partial muscarinic agonist
• Uses: Glaucoma, chemotherapy
• Side effect: Dry mouth

Nicotine:

• Agonist nicotinic receptors
• Low dose: Ganglionic stimulation by depolarization
• High doses: Ganglionic blockage and neuromuscular blockade

Question 4

Adverse effects of Muscarnic agonists

Answer 4

1) Sweating
2) Salvation
3) Flushing
4) Low BP
5) Nausea
6) Abdominal pain
7) Diarrhea
8) Bronchospasm

Question 5

• Indirect-acting Cholinergic Agonists (Anticholinesterases)

- Inhibit achetylcholinesterase (AchE)

Answer 5

• Retain acetylcholine

1) Edrophonium
- Bind reversible to active site of the enzyme
- Can’t enter CNS
- Uses: Myasthenia gravis = bc increases muscle strength by reversing neuromuscular blockers

2) Carbamates
- Form a covalent bond w the enzyme
- Kinds:
1) Physostigmine = Can enter CNS, Uses: overdoses of anticholinergic drugs

2) Neostigmine = Can’t enter CNS, urinary retention, myasthenia gravis
3) Pyridostigmine = Can’t enter CNS, Myasthenia gravis

3) Organphosphates
- Phospholate the enzyme
- Kinds:
1) Malathion = Insecticides/toxins

2) Sarin = Insecticides/toxins

Question 6

Anticholinesterases effects on organs

Answer 6

Neruomuscular junction:

• Increases strength contraction
• Reverses action of nondepolarizing neuromuscular blockers
• Useful in myasthenia gravis

Question 7

Cholinergic Antagonists, (Muscarinic Antagonists)

Answer 7

1) Ipratropium
Uses:
-Treatment for chronic pulmonary disease
-Asthma

2) Tropicamide
Uses:
-Mydriatic for fundscopy
-Produces mydrasis w/ cycloplegia (dilation)

Belladonna Alkoids:
3) Atrophine:
Actions:
- M3 Blockage (in sym)
-Atrial M2 Blockade (increase HR/Contraction)
Uses:
-Antidote for cholinergic agonists

4) Scopolamine:
- Prevents motion sickness

Question 8

Contraindications of Antimuscarinic Agents

Answer 8

Adverse effects on

• pt’s w angle-closure glaucoma
• Pt’s w prostatic hypertrophy
• Elderly pt’s

Question 9

Cholinergic Antagonists, (Neuromuscular Blockers, NM)

Answer 9

1) Tubocurarine
Uses:
-Anesthesia (relax skeletal muscles)

2) Succinylcholine
Uses:
-Desensitizes receptors bc overstimulation in synaptic cleft = flaccid paralysis (weakness/decreased muscle tone)

Question 10

Cholinergic Antagonists

Nicotinic Receptor Antagonists

Answer 10

• Ganglion Blockers
• Replaced by superior hypertensive agents

1) Hexamethonium
Uses:
-Treats Hypertension
-Remove dominant control of organs

Question 11

Cholinergic Antagonists

Drugs that act Presynaptically

Answer 11

• Botulinum Toxin (Botox)
• Inhibits acetylcholine release

Uses:

• Muscle spasms
• Wrinkles

Question 12

Adrenergic agonists 
(what do they treat?)

Answer 12

Treats:
• Hypertension
• Angina
• Heart failure
• Arrhythmias
• Asthma
• Migraine
• Anaphylactic reactions

Question 13

Epinephrine

General facts,
high dose,
low dose,
uses

Answer 13

Generally:

• Can cause bronchodilator
• Constricts skin and blood vessel

High dose:
-Alpha-1 (dominant) and Beta-2 receptors = activated
High dose given when BP increases bc
1) Vasoconstriction
2) Increased HR
3) Increased ventricular contraction

Low dose:
-Beta-2 receptors more sensitive than Alpha-1
Effects:
1) Vasodilation
2) Systolic pressure increases
3) HR increases

• Uses:
• Anaphalactic shock
• Asthma
• Cardiac arrest

Question 14

Receptor D1 D5

Answer 14

Signal: Increases cAMP

Location: Smooth muscle of the renal vascular bed

Response: Relaxation

Question 15

Adrenergic Agonists

Direct-Acting (full list, no functions)

Answer 15

Direct acting:

1) Endogenous Catecholamines
- Norepinephrine
- Epinephrine
- Dopamine
- Partial B-Agonists

2) Alpha-Agonists
Alpha-1-Selective:
-Phenylephrine

Alpha-2-Selective:
-Clonidine

3) B-Agonists
Non-Selective (B1 and B2):
-Isoproterenol

B1-Selective:
-Dobutamine

B2-Selective:
-Albuterol

Question 16

Direct acting Adrenergic agonists

(Endogenous
Catceholamines)

Answer 16

1) Norepinephrine
- Agonist at Alpha-1, Alpha-2, and Beta-1 receptors
- Vasoconstriction (α1 effect).
- Increases cardiac contractility (β1 effect)
- bradycardia
- Treats: Shock

2) Epinephrine
-Agonist at both Alpha and Beta adrenoceptors
(Low dose= Beta-1 Beta-2)
(High dose= Alpha-1)
-Sympathetic @ high doses
-Low dose= vasodilation/increase systolic pressure

3) Dopamine

Question 17

B-Agonists

Answer 17

DIRECT

Non-selective (B1 and B2):

1) Isoproterenol
- Bronchodilation (add MOREE)

B1-Selective:
1) Dobutamine: 
-Mild vasodilation
-Increases myocardial O2 consumption
Uses: Acute heart failure, cardiogenic shock

B2-Selective:
1) Albuterol:
-Bronchodilation
Uses: Asthma

Question 18

Alpha-Adrenergic Agonists

Answer 18

DIRECT

Alpha-1 Selective
1) Phenylephrine
-Vasocontraction
Uses; Nasal decongestion, Mydriatic (dilates pupil)

2) Alpha-2 Selective
1) Clonidine
-Reduces blood pressure
Uses: antihypertensive

Question 19

Adrenergic Agonist

Indirect acting

Answer 19

Releasing Agents:
-Cause norepinephrine release from presynaptic terminals

1) AMPHETAMINE
-Increases BP
Uses:
-ADHD
-Narcolepsy

2) TYRAMINE
- Release norepinephrine
- MAO inhibitors (antidepressants), it can precipitate serious vasopressor episodes.

Uptake Inhibitors
3) COCAINE
• Blocks monoamine reuptake.
• Monoamines accumulate in synaptic space.
-prolongation of their central and peripheral
actions

Question 20

Adrenergic Agonist

Mixed acting

Answer 20

1) Ephedrine
-Releases norepinephrine
-Long duration
-Penetrates CNS
Uses: Pressor agent (EX: spinal anesthesia)

2) Pseudophedrine
(Sudafed)
Uses: Decongestion

Question 21

Baroreceptors

Answer 21

• Low BP = blood vessel triggers sympathetic = vasodilation
• High BP = blood vessel triggers parasympathetic = vasoconstriction
• Balances*

Question 22

Adrenergic Antagonists

Beta-Blockers

Answer 22

All B-Antagonists

1) Propranolol
- Decreases HR and heart contractibility
- Don’t use on ppl with Asthma
- Decreases glycogenolysis/glucagon secretion

B1-Antagonists

1) Atenolol
- Use: Hypertensive pt’s
- Decreases HR and constriction of blood vessels

Partial Agonists

1) Pindolol
- Use: Bradycardia

All decrease Camp levels

Question 23

Beta-Blocker: (antagonists)

Adverse Effects

Answer 23

1) Lipid metabolism
- Inhibits release of fatty acids from adipose tissue
- Increase TG
- Reduce HDL

2) CNS Effects
- Sedation
- Dizziness
- Lethargy
- Fatigue

Question 24

Beta Blockers:

General Uses

Answer 24

1) Hypertension
2) Glaucoma
3) Migraine
4) Hyperthyroidism
5) Agina Pectoris
6) Atrial Fibrillation
7) Myocardial Infraction
8) Performance Anxiety
9) Essential Tremor

Question 25

Andrenergic Antagonists

Alpha Blockers

Answer 25

Alpha blockers:
All Alphas:
1) Phenoxybenzamine
-Unsuccessful with hypertension

2) Phenotolamine
- Controls hypertension before/after surgery

Alpha-1:
1) Prazosin
Uses: 
-Treats Hypertension
-Treats benign prostatic hyperplasia (Relaxes smooth muscle of bladder)
(However not drug of choice)