Muscle Blockers

Question 1

why don’t muscle blockers effect the brain or CNS?

Answer 1

polar compounds can’t go thru BBB so must give IV

Question 2

how long do short acting non depolarizing neuromuscular blockers work? long acting? what is the only long acting neuromuscular blocker?

Answer 2

short: 30-60 minutes
long: 60-120 minutes

only long acting: pancuronium

Question 3

increasing the length of use of non depolarizing muscle blocker does what to duration of action?

Answer 3

prolongs it

remember for ICU

Question 4

how to reverse effects of non depolarizing agent?

Answer 4

acetylcolinesterase inhibitors to increase ACh concentration

Question 5

what mm is last affected by non depolarizing blockers?

Answer 5

diaphragm

Question 6

DOA of succinylcholine?

Answer 6

5-10 minutes

Question 7

MOA of succinylcholine

Answer 7

binds & activates the nicotinic receptor once causing one transmission of an impulse to the muscle.

Doesn’t transmit anymore and doesn’t leave the receptor either.

It sits there blocking the channel

Normal closure of the gate is prevented and the blocker moves in and out rapidly

Muscle stays in depolarized state, unable to repolarize while succinylcholine sits there.

Question 8

how long do fasciculations last after dosing succinylcholine? how long until paralysis?

Answer 8

30 seconds of fasciculations

90 seconds until paralysis

Question 9

CVS affects of nondepolarzing blockers?

Answer 9

hypotension (prevent with antihistamines)

tachycardia

Question 10

CVS affects of depolarizing blockers?

Answer 10

arrhythmia when given with other anesthetics

Question 11

what drug causes hyperkalemia? who does it happen to?

Answer 11

succinylcholine if given to pt with burns, nerve damage, neuromuscular disease, or trauma

Question 12

what drug causes most mm pain after paralysis?

Answer 12

succinylcholine

Question 13

succinylcholine + volatile anesthetics =

Answer 13

malignant hyperthermia from abnormal release of Ca from stores in skeletal mm

treatment: dantrolene

Question 14

muscular blockers + aminoglycosides (Abx) =

Answer 14

increased blockade

Abx decrease the release of ACh and can lead to respiratory depression

Question 15

increased age + NM blockers =

Answer 15

increased effect (decrease dose if older than 70)

Question 16

NM+ myasthenia gravis =

Answer 16

increased effect

Question 17

NM + severe burn or UMNL =

Answer 17

decreased effect

Question 18

benefits of NM blockers in ventilation

Answer 18

increases O2

decreases atelectasis

Question 19

NM blocker + intubation =

Answer 19

upper airway muscle relaxation

safer to put tube down first

Question 20

cause of muscle spasticity?

Answer 20

increased tonic stretch of reflex (DTR) or flexor mm spasm (increased tone)

often get with mm weakness

caused by spinal injury
CP
MS
stroke

Question 21

MOA of spasmolytics

Answer 21

change stretch reflex arc (DTR) or act on mm directly (dantrolene)

decrease pain but don’t fix dysfunction

Question 22

Diazepam MOA

Answer 22

increases GABA which hyper polarizes cell (decreases excitability of mm)

Question 23

use of diazepam?

Answer 23

any spasticity (spinal cord transection, CNS origin) q

Question 24

SE of diazepam as spasmolytic?

Answer 24

CNS sedation

Question 25

Baclofen MOA?

Answer 25

agonizes GABA (decreases excitatory NT in brain and substance P in spinal cord)

Question 26

clinical use of baclofen?

Answer 26

given PO (intrathecal if severe)

as effective as diazepam w/o sedation

no effect on mm strength like dantrolene

addiction or spasms

Question 27

SE of baclofen?

Answer 27

drowsiness (tolerance occurs)

anticholinergic effects

increased seizure potential when drug is stopped (if epileptic)
- withdraw dose slowly

Question 28

MOA of tizanidine?

Answer 28

CNS alpha 2 adrenergic agonist (like clonidine)

Question 29

use of tizanidine?

Answer 29

spasticity from cerebral or spinal injury (equally effective to the others)

Question 30

SE of tizanidine?

Answer 30

drowsiness
hypotension
dry mouth
asthenia (perceived loss of strength)

Question 31

MOA of dantrolene?

Answer 31

works in mm fibers
prevents release of calcium in skeletal mm (prevents contraction)

little effect on cardiac/smooth mm

Question 32

clinical uses of dantrolene?

Answer 32

spams (CNS or spinal cord), and malignant hyperthermia

Question 33

SE of dantrolene

Answer 33

generalized mm weakness, sedation, symptomatic hepatitis (with >800mg/d)

Question 34

what is malignant hyperthermia?

Answer 34

prolonged release of Ca from mm leads to massive contraction

increased lactic acid

fever

death

Question 35

use of cyclobenazprine and its look alikes

Answer 35

acute mm spasm caused by tissue trauma or strain (not for spasms from spinal cord or brain injuries)

usually nonspecific back pain

Question 36

SE of cyclobenazprine and its look alike?

Answer 36

strongly anticholinergic
drowsy
confusion
visual hallucinations

Question 37

drugs used for severe mm spasms due to euro injury?

Answer 37

diazepam
baclofen
tizanidine
dantrolene

Question 38

drugs used for mm pain/injury syndromes where spasms is cause of pain or secondary to local mm:

Answer 38

ophenadrine
carisoprodol
cyclobenzaprine
metaxalone
methocarbamol

Question 39

what population do u need to be careful with, with spasmolytics?

Answer 39

elderly (increased SE)