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Flashcards in Skeletal Muscle Relaxants Deck (34):
1

what are neuromuscular blockades

-depolarizing blocker: succinylcholine
-non depolarizing blocker: benzylisoquinolines and ammonio steroids

2

what are the benzylisoquinolines and the ammonio steroids

Benzylisoquinolines: Cisatracurium, Atracurium, Mivacurium, Tubocurarine

Ammonio Steroids (curoniums) - Pancuronium, Vecuronium, Rocuronium

3

mechanism of action of non depolarizing blockers

-competitive antagonist of nicotonic receptors
-large doses, enter the pores of ion channels for a more intense motor blockade
-block prejunctional Na channels --> reducing release of acetylcholine

4

how can non depolarizing blockade be reversed

using acetylcholinesterase inhibitors -- neostigmine and edrophonium --> increase amount of acetylcholine in the cleft

5

what is the phase I block or depolarization block of succinylcholine

bind to nicotinic receptors --> depolarize as acetylcholine would --> not metabolized effectively --> muscle unresponsive to additional impulses --> flaccid paralysis

6

what hydrolyzes succinylcholine/ reverses phase I or depolarization block of succinylcholine

plasma butyrylcholinesterase aka pseudocholinesterase

7

what is the phase II block or desensitization block of succinylcholine

single large dose, repeated doses, or prolonged infusion of succinylcholine repolarizes the membrane --> membrane can't become depolarized because it is desensitized --> channel act like in prolonged closed state

8

what can reverse phase II block or desensitization block of succinylcholine

acetylcholinesterase inhibitors -- neostigmine and edrophonium

9

which of the non depolarizing blocker has a metabolite that can cause hypotension and seizures

Atracurium --> metabolite is Laudanosime --> transient hypotension and seizures (if higher doses)

10

how is Atracurium inactivated

non specific plasma esterases and by spontaneous reaction called Hoffman elimination --> hence duration not altered by absence of renal function

Cisatracurium (stereoisomer)

11

only non depolarizing blocker classified as short acting and its significance

Mivacurium --> hydrolyzed by butyrylcholinesterase --> not dependent on liver or kidney for elimination

12

most rapid onset among all the non depolarizing blocker and can replace succinylcholine

Rocuronium

13

AE of non depolarizing blockers

Histamine Release (Tubocurarine)
Ganglion blockade (Tubocurarine) --> hypotension and tachycardia
Cardiac Muscarinic Receptor blocker (Pancuronium) --> moderate tachycardia

14

AE of depolarizing blocker

-succinylcholine stimulates nicotinic receptors in sympathetic and parasympathetic and muscarinic in heart

Malignant Hyperthermia (esp with halogenated hydrocarbons anesthetics)
Bradycardia
Histamine Release
Muscle pain
Hyperkalemia (loss of tissue K during depolarization)
Increased intraocular pressure
Increased intragastric pressure

15

how do you treat malignant hyperthermia

dantrolene - prevents release of Ca from sarcoplasmic reticulum

16

signs of histamine release

erythema of face and upper chest
transient hypotension
increased HR

17

how can tetracyclines produce neuromuscular blockade

chelating calcium so no calcium release for action potential

18

how can antibiotic aminoglycoside cause neuromuscular blockade

inhibiting ACh release from preganglionic terminal by competing with calcium

19

types of patients that are resistant to non depolarizing muscle relaxants and require additional non depolarizing relaxants

severe burn and UMN disease

20

what disease increases neuromuscular blockade caused by non depolarizing muscle relaxants

Myasthenia Gravis

21

contraindication of succinylcholine

-family or personal history of Malignant Hyperthermia, Skeletal Muscle Myopathies, and Hypersensitivity to drug

-major burns, multiple trauma, extensive denervation of skeletal muscle, UMN injury because succinylcholine can cause hyperkalemia and this results in cardiac arrest in these patients

22

muscarinic antagonist used post surgery and why

Atropine or Glycopyrrolate --> used together with neostigmine and edrophonium (used to reverse the non depolarizing blockade) --> prevent stimulation of muscarinic receptors and avoid bradycardia

23

what is succinylcholine mainly use for

endotracheal intubation
ECT

24

Spasmolytics that work in the CNS

Diazepam
Baclofen
Tizanidine

25

when is diazepam used as a spasmolytic

muscle spasm of any origin --> produces sedation in most patients in doses required to reduce muscle tone

26

mechanism of Baclofen

GABA agonist --> hyperpolarization due to increased K conductance

27

when is Balcofen used

spasticity in Multiple Sclerosis
Spinal cord injuries and diseases

28

mechanism and use of Tizanidine

alpha 2 agonist in the CNS --> MS and spinal cord injury

29

spasmolytics that work on skeletal muscle

Dantrolene
Botulinum Toxin

30

when is dantrolene used

Malignant Hyperthermia

31

when is Botulinum Toxin used

Blepharospasm - persistent and disabling eyelid spasm
Local muscle spasm
Cerebral Palsy

32

spasmolytics used for acute local spasm

Cyclobenzaprine

33

what is cyclobenzaprine used for

acute, painful, musculoskeletal conditions

34

AE of cyclobenzaprine

sedation, confusion, and transient visual hallucinations

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