Skeletal Muscle Relaxants Flashcards
Spasmolytics/Antispasmodics: chronic use (CNS and muscle action)
CNS:
- baclofen
- diazepam
- tizanidine
- cyclobenzaprine
Muscle Action:
- dantrolene
- botulinum toxin
Spasmolytics/Antispasmodics: acute use
cyclobenzaprine
Spasmolytics/Antispasmodics: what 2 conditions do these drugs treat?
spasmolytics: spasticity from upper motor neuron lesions
antispasmodics: spasms from peripheral msk conditions
Baclofen: MOA
spinal inhibition of motor neurons
GABA(B) agonist (pre and postsynaptic inhibition)
Baclofen: uses
sev spasticity due to CP, MS, stroke
Baclofen: ADEs
sedation
muscle weakness
rebound spasticity upon abrupt withdrawal
Diazepam: MOA
GABA(A) receptor activation (postsynaptic)
facilitates GABAergic transmission in CNS
Diazepam: uses
chronic spasm due to CP, stroke, SCI
**acute spasm due to muscle injury
Diazepam: ADEs
sedation
additive w/ other CNS depressants
antegrade amnesia
abuse potential
Tizanidine: MOA
pre and postsynaptic inhibition of reflex motor output
alpha2 agonist in spinal cord
Tizanidine: uses
spasm due to MS, stroke (CVA), ALS
Tizanidine: ADEs
weakness sedation hypotension rebound HTN w/ abrupt withdrawal hepatotoxicity
Cyclobenzaprine: MOA
inhibition of spinal stretch reflex
reduces of hyperactive muscle reflexes
antimuscarinic effects
Cyclobenzaprine: uses
acute spasm due to muscle injury or inflammation
Cyclobenzaprine: ADEs
strong antimuscarinic effects
sedation
confusion
ocular effects
Antispasmodics: agents
Carisoprodol (Soma) Chlorzoxazone (Parafon Forte) Metaxalone (Skelaxin) Methocarbamol (Robaxin) Orphenadrine (Norflex)
Antispasmodics: uses, MOA
acute muscle spasm
act at the level of the brainstem
Carisoprodol
schedule IV
metabolized to meprobamate
withrdrawal: anxiety, tremors, muscle twitching, insomnia, auditory/visual hallucinations (taper slowly over 14d)
Dantrolene: MOA
direct acting on skeletal muscle (blocks Ca channels)
weakens muscle contraction by reducing myosin actin interaction
Dantrolene: uses
IV: malignant hyperthermia
oral: spasm due to CP, SCI, MS
Dantrolene: ADEs
muscle weakness
hepatotoxicity
Botulinum Toxin: MOA
flaccid paralysis
Botulinum Toxin: uses
spasm due to CP MS OAB migraine cervical dystonia hyperhidrosis
Botulinum Toxin: ADEs
muscle weakness
falls
Which drugs are used in the treatment of CP?
baclofen
diazepam
dantrolene (PO)
botulinum toxin
Which drugs are used in the treatment of MS?
baclofen
tizanidine
dantrolene (PO)
botulinum toxin
Which drugs are used in the treatment of strokes?
baclofen
diazepam
tizanidine
Which drug is used in the treatment of ALS?
tizanidine
Which drugs are used in the treatment of spinal cord injury?
diazepam
dantrolene (PO)
Which drug is used in the treatment of malignant hyperthermia?
IV dantrolene
