Skeletal Muscle Relaxants

Question 1

Spasmolytics/Antispasmodics: chronic use (CNS and muscle action)

Answer 1

CNS:

• baclofen
• diazepam
• tizanidine
• cyclobenzaprine

Muscle Action:

• dantrolene
• botulinum toxin

Question 2

Spasmolytics/Antispasmodics: acute use

Answer 2

cyclobenzaprine

Question 3

Spasmolytics/Antispasmodics: what 2 conditions do these drugs treat?

Answer 3

spasmolytics: spasticity from upper motor neuron lesions
antispasmodics: spasms from peripheral msk conditions

Question 4

Baclofen: MOA

Answer 4

spinal inhibition of motor neurons

GABA(B) agonist (pre and postsynaptic inhibition)

Question 5

Baclofen: uses

Answer 5

sev spasticity due to CP, MS, stroke

Question 6

Baclofen: ADEs

Answer 6

sedation
muscle weakness
rebound spasticity upon abrupt withdrawal

Question 7

Diazepam: MOA

Answer 7

GABA(A) receptor activation (postsynaptic)

facilitates GABAergic transmission in CNS

Question 8

Diazepam: uses

Answer 8

chronic spasm due to CP, stroke, SCI

**acute spasm due to muscle injury

Question 9

Diazepam: ADEs

Answer 9

sedation
additive w/ other CNS depressants
antegrade amnesia

abuse potential

Question 10

Tizanidine: MOA

Answer 10

pre and postsynaptic inhibition of reflex motor output

alpha2 agonist in spinal cord

Question 11

Tizanidine: uses

Answer 11

spasm due to MS, stroke (CVA), ALS

Question 12

Tizanidine: ADEs

Answer 12

weakness
sedation
hypotension
rebound HTN w/ abrupt withdrawal
hepatotoxicity

Question 13

Cyclobenzaprine: MOA

Answer 13

inhibition of spinal stretch reflex

reduces of hyperactive muscle reflexes

antimuscarinic effects

Question 14

Cyclobenzaprine: uses

Answer 14

acute spasm due to muscle injury or inflammation

Question 15

Cyclobenzaprine: ADEs

Answer 15

strong antimuscarinic effects
sedation
confusion
ocular effects

Question 16

Antispasmodics: agents

Answer 16

Carisoprodol (Soma) 
Chlorzoxazone (Parafon Forte)
Metaxalone (Skelaxin)
Methocarbamol (Robaxin)
Orphenadrine (Norflex)

Question 17

Antispasmodics: uses, MOA

Answer 17

acute muscle spasm

act at the level of the brainstem

Question 18

Carisoprodol

Answer 18

schedule IV

metabolized to meprobamate

withrdrawal: anxiety, tremors, muscle twitching, insomnia, auditory/visual hallucinations (taper slowly over 14d)

Question 19

Dantrolene: MOA

Answer 19

direct acting on skeletal muscle (blocks Ca channels)

weakens muscle contraction by reducing myosin actin interaction

Question 20

Dantrolene: uses

Answer 20

IV: malignant hyperthermia

oral: spasm due to CP, SCI, MS

Question 21

Dantrolene: ADEs

Answer 21

muscle weakness

hepatotoxicity

Question 22

Botulinum Toxin: MOA

Answer 22

flaccid paralysis

Question 23

Botulinum Toxin: uses

Answer 23

spasm due to CP
MS
OAB
migraine
cervical dystonia
hyperhidrosis

Question 24

Botulinum Toxin: ADEs

Answer 24

muscle weakness

falls

Question 25

Which drugs are used in the treatment of CP?

Answer 25

baclofen
diazepam
dantrolene (PO)
botulinum toxin

Question 26

Which drugs are used in the treatment of MS?

Answer 26

baclofen
tizanidine
dantrolene (PO)
botulinum toxin

Question 27

Which drugs are used in the treatment of strokes?

Answer 27

baclofen
diazepam
tizanidine

Question 28

Which drug is used in the treatment of ALS?

Answer 28

tizanidine

Question 29

Which drugs are used in the treatment of spinal cord injury?

Answer 29

diazepam

dantrolene (PO)

Question 30

Which drug is used in the treatment of malignant hyperthermia?

Answer 30

IV dantrolene