Agonist And Antagonists Of Cholinergic And Adrenergic Flashcards
Effects of small and large doses of acetylcholine
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
Cholinegic Agonists:
Direct Acting drugs (Choline esters)
-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
Cholinergic Agonists:
Direct acting drugs (Natural Alkaloids)
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
Adverse effects of Muscarnic agonists
1) Sweating
2) Salvation
3) Flushing
4) Low BP
5) Nausea
6) Abdominal pain
7) Diarrhea
8) Bronchospasm
- Indirect-acting Cholinergic Agonists (Anticholinesterases)
- Inhibit achetylcholinesterase (AchE)
- 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
Anticholinesterases effects on organs
Neruomuscular junction:
- Increases strength contraction
- Reverses action of nondepolarizing neuromuscular blockers
- Useful in myasthenia gravis
Cholinergic Antagonists, (Muscarinic Antagonists)
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
Contraindications of Antimuscarinic Agents
Adverse effects on
- pt’s w angle-closure glaucoma
- Pt’s w prostatic hypertrophy
- Elderly pt’s
Cholinergic Antagonists, (Neuromuscular Blockers, NM)
1) Tubocurarine
Uses:
-Anesthesia (relax skeletal muscles)
2) Succinylcholine
Uses:
-Desensitizes receptors bc overstimulation in synaptic cleft = flaccid paralysis (weakness/decreased muscle tone)
Cholinergic Antagonists
Nicotinic Receptor Antagonists
- Ganglion Blockers
- Replaced by superior hypertensive agents
1) Hexamethonium
Uses:
-Treats Hypertension
-Remove dominant control of organs
Cholinergic Antagonists
Drugs that act Presynaptically
- Botulinum Toxin (Botox)
- Inhibits acetylcholine release
Uses:
- Muscle spasms
- Wrinkles
Adrenergic agonists (what do they treat?)
Treats: • Hypertension • Angina • Heart failure • Arrhythmias • Asthma • Migraine • Anaphylactic reactions
Epinephrine
General facts,
high dose,
low dose,
uses
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
Receptor D1 D5
Signal: Increases cAMP
Location: Smooth muscle of the renal vascular bed
Response: Relaxation
Adrenergic Agonists
Direct-Acting (full list, no functions)
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
Direct acting Adrenergic agonists
(Endogenous
Catceholamines)
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
B-Agonists
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
Alpha-Adrenergic Agonists
DIRECT
Alpha-1 Selective
1) Phenylephrine
-Vasocontraction
Uses; Nasal decongestion, Mydriatic (dilates pupil)
2) Alpha-2 Selective
1) Clonidine
-Reduces blood pressure
Uses: antihypertensive
Adrenergic Agonist
Indirect acting
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
Adrenergic Agonist
Mixed acting
1) Ephedrine
-Releases norepinephrine
-Long duration
-Penetrates CNS
Uses: Pressor agent (EX: spinal anesthesia)
2) Pseudophedrine
(Sudafed)
Uses: Decongestion
Baroreceptors
- Low BP = blood vessel triggers sympathetic = vasodilation
- High BP = blood vessel triggers parasympathetic = vasoconstriction
- Balances*
Adrenergic Antagonists
Beta-Blockers
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
Beta-Blocker: (antagonists)
Adverse Effects
1) Lipid metabolism
- Inhibits release of fatty acids from adipose tissue
- Increase TG
- Reduce HDL
2) CNS Effects
- Sedation
- Dizziness
- Lethargy
- Fatigue
Beta Blockers:
General Uses
1) Hypertension
2) Glaucoma
3) Migraine
4) Hyperthyroidism
5) Agina Pectoris
6) Atrial Fibrillation
7) Myocardial Infraction
8) Performance Anxiety
9) Essential Tremor