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Acetylcholine Receptor Antagonists Flashcards

1
Q

Muscarinic receptor antagonists - MoA

A

Compete with Ach for its receptors at parasympathetic neuroeffector junctions and thereby inhibits the effects of parasympathetic nerve stimulation

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2
Q

Muscarinic receptor antagonists - Effects

A

Ocular: Mydriasis (relaxing of iris sphincter muscle). Flattenes the lens (relaxing ciliary muscle–> focus distal objects), Dry eyes (inh lacrimal gland secretion)

Cardiac: Increased HR and AV conduction velocity (block the effect of vagal nerve of SA and AV node)

Respiratory: Bronchial smooth muscle relaxation and bronchodilation, reduced secretion in upper and lower resp tract

GI and UT: Gastroesophageal reflux (reduced lower esophageal muscle tone), increased gastric emptying time (relaxes GI muscle tone), reduces intestinal motility, inh gastric acid secretion. Relaxes urinary bladder (relaxing detrusor muscle)

CNS: produce sedation and excitement

Other: hyperthermia (inh sweating)

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3
Q

Muscarinic receptor antagonists - Indications

A

Ocular: Produce mydriasis (ophthalmoscopic exam of peripheral retina), produce cycloplegia, iritis and cyclitis

Respiratory: Reduce salivary and resp secretions –> prevent airway obstruction in pt who are receiving general anesthetics

GI and UT: intestinal spasms and pain, urinary bladder spams in pt w overactive bladder

CNS: Parkinson, motion sickness

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4
Q

Muscarinic receptor antagonists - Adverse effects

A 
Cycloplegia
Dry eyes and mouth, decreased sweating
Constipation
Urinary retention
Delirium and Hallucinations
Hyperthermia (Hot, dry, flushed skin)
Increased HR, tachycardia, palpitations
Blurred vision
Thirst
Decreased clearance of mucus from lungs (because of impaired ciliary activity) --> accumulation of viscid material in airways
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5
Q

Muscarinic receptor antagonists - Groups

A

Belladonna alkaloids

Synthetic

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6
Q

Belladonna alkaloids

A

Atropine
Scopolamine
Hyoscyamine

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7
Q

Atropine - Indication

A

Sinus bradycardia
Symptomatic AV block (Increase AV conduction velocity)
Prevent muscarinic side effects when cholinesterase inh are given to pt with myasthenia gravis

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8
Q

Atropine - Adverse effects

A

Atropine toxicity: Antisecretory, paralysis of accommodation, vasodilation
Ventricular fibrillaton
Supraventricular or ventricular tachycardia

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9
Q

Scopolamine - MoA

A

Blocks Ach neurotransmission from vestibular apparatus to the vomiting center in the brain stem

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10
Q

Scopolamine - Indication

A

Motion sickness

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11
Q

Hyoscyamine - Indication

A

Intestinal spasms + other GI symptoms

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12
Q

Synthetic muscarinic receptor antagonists

A 
Glycopyrrolate
Ipratropium
Tiotropium
Dicyclomine
Oxybutynin
Solifenacin
Tolterodine
Fesoterodine
Darifenacin
Trospium
Tropicamide
Cyclopentolate
Pirenzepine
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13
Q

Glycopyrrolate - MoA

A

Blocks muscarinic receptors throughout the body

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14
Q

Glycopyrrolate - Indication

A

Increases AV conduction velocity
Reduces salivary and resp secretions –> prevent airway obstruction in anesthesia
Anesthesia: inh secretory and vagal effects on cholinesterase inh used to reverse nondepolarizing neuromuscular blockade induced by curari form drugs
Prevents muscarinic side effects when cholinesterase inh are used in myasthenia gravis

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15
Q

Which synthetic muscarinic receptor antagonists are used for obstructive lung diseases?

A

Ipratropium and Tiotropium

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16
Q

Dicyclomine - MoA and Indication

A

Relaxes intestinal smooth muscle

Irritable bowel symptoms - intestinal cramping

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17
Q

Oxybutynin, Solifenacin, Tolterodine, Fesoterodine, Darifenacin and Trospium - Indication

A

Overactive bladder: reduces daytime urinary frequency, nocturia, urgency and incontinence

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18
Q

Oxybutynin, Solifenacin, Tolterodine, Fesoterodine, Darifenacin and Trospium - Adverse effects

A

Dry mouth and blurred vision

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19
Q

Tropicamide and Cyclopentolate - Indication

A

Short-term mydriasis

Pupillary dilator before ophthalmoscopy for exam of peripheral retina

20
Q

Pirenzepine - MoA

A

Blocks M1 receptors on paracrine cells and inh release of histamine. Reduces gastric acid secretion

21
Q

Pirenzepine - Indication

A

Peptic ulcer

22
Q

Nicotinic receptor antagonists - Groups

A

Ganglionic and Neuromuscular blocking agents (nondepolarizing blockers and depolarizing blockers)

23
Q

Ganglionic blocking agent

A

Mecamylamine

24
Q

Ganglionic blocking agents - MoA

A

Block autonomic ganglia to reduce excessive activity of the sympathetic and parasympathetic nervous system by inh transmission between preganglionic and postganglionic neurons. No selectivity for sympathetic or parasympathetic ganglia.

25
Ganglionic blocking agents - Indication
Used for severe essential hypertension and malignant hypertension before, but not used today due to no selectivity and adverse effect
26
Neuromuscular blocking agents - MoA
Binds to the muscle type of nicotinic ACh receptor and inh neurotransmission at skeletal neuromuscular junctions, causing muscle weakness and paralysis
27
Neuromuscular blocking agents - Special consideration/ Adverse effect
Complete respiratory failure in a pt lacking external ventilatory support Anesthesia awareness
28
Nondepolarizing neuromuscular blocking agents / Curariform drugs
``` Atracurium Cisatracurium Pancuronium Rocuronium Tubocurarine Vecuronium Doxacurium ```
29
Nondepolarizing neuromuscular blocking agents - MoA
Competitive antagonists of ACh at nicotinic receptos in skeletal muscle at the neuromuscular junction. Stimulate release of histamine and block autonomic ganglia and muscarinic receptors.
30
Nondepolarizing neuromuscular blocking agents - Effects
First: paralyzes the small and rapid moving muscle of the eyes and face Then: paralyzes larger muscles of the limbs and the trunk Last: paralyzed intercostal muscles and diaphragm --> respiration cease
31
Nondepolarizing neuromuscular blocking agents - Indication
``` Induce muscle relaxation (surgery) Electroconvulsive therapy (prevent injuries due to muscle contraction) Intubation of resp tract (endoscopic procedure) ```
32
In what kind of patients are the paralytic agents more pronounced? And how are they potentiated?
Patients with neuromuscular disorders such as myasthenia gravis. Potentiated by inhalation anesthetic agents, aminoglycosides, tetracyclines and calcium channel blockers
33
How can muscle relaxing effect of nondepolarizing neuromuscular blocking agents be reversed?
Adm a cholinesterase inhibitor
34
Nondepolarizing neuromuscular blocking agents - Adverse effects
Bronchospasm Hypotension Tachycardia Caused by histamine release
35
Pancuronium - Indication
Lethal injection protocols
36
Sugammadex - MoA
Forms a tight inactive complex with rocuranium and vecuronium and removes the drugs from the neuromuscular junction.
37
Sugammadex - Indication and Effect
Complete paralysis | Reverses neuromuscular blocking agents
38
Which nondepolarizing neuromuscular blocking agents have long duration of action
Pancuronium and Doxacurium. Rest have intermediate
39
Depolarizing neuromuscular blocking agent
Succinylcholine
40
Succinylcholine - MoA
Binds to nicotinic receptors in skeletal muscle and causes persistent depolarization of the motor end plate. Phase 1: depolarization --> muscle fasciculations Phase 2: desensitization caused by overstimulation and leads to resistance
41
Succinylcholine - Indication
Produce muscle relaxation (surgery, intubation) | Preferred for adults with emergency airway situations
42
Succinylcholine - Special considerations and Contraindication
Short duration of action (5-10 min) Effects not reversed by cholinesterase inh Monitor serum potassium Contraindication: Atypical cholinesterase (no metabolization --> prolonged neuromuscular paralysis and apnea), Patients with unhealed skeletal muscle injury, spinal cord injury, Children
43
Succinylcholine - Adverse effects
Hyperkalemia --> Cardiac arrest in pt with unhealed skeletal muscle injury or conditions involving muscle weakness, Children Postop myalgia (muscles of neck, back, abdomen) Malignant hyperthermia (inhalation anesthetics)
44
Muscarinic receptor antagonists - Contraindications
Narrow-angle glaucoma Coronary artery disease BPH
45
Antimuscarinic drugs for Parkinsons disease
Benzatropine | Trihexyphenidyl

Pharmacology (55 decks)

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