Skeletal muscle relaxants

Question 1

What muscle relaxers are for acute use

Answer 1

Cyclobenzaprine

Question 2

What chronic muscle relaxers act on the CNS

Answer 2

Baclofen
Cyclobenzaprine
Diazepam
Tizanidine

Question 3

What chronic muscle relaxers act on muscles

Answer 3

Dantrolene

Botulinum toxin

Question 4

Most spasmolytic drugs act

Answer 4

on the CNS to reduce abnormally elevated tone caused by neirologic or muscle end plate disease

Question 5

What is the MOA of Baclofen

Answer 5

Acts centrally to reduce release of excitatory transmitters in brain and spinal cord
Suppress activity of la sensory afferents, spinal interneurons, and motor neurons
Activates GABA-b receptors pre- and post-synaptically
(admin is PO or intrathecally)

Question 6

Baclofen is used for

Answer 6

severe spasticity due to cerebral palsy, MS, and stroke

Question 7

ADE of Baclofen are

Answer 7

Sedation

Muscle weakness

Question 8

What is the MOA of cyclobenzaprine (flexeril)

Answer 8

Acts centrally to reduce hyperactive muscle reflexes
Poorly understood, but inhibits spinal stretch reflex
Antimuscarinic effects
lasts 4-6 hours, hepatic metabolism

Question 9

Cyclobenzaprine is used for

Answer 9

acute spasm 2/2 muscle injury or inflammation

Question 10

ADE of Cyclobenzaprine include

Answer 10

Antimuscarinic
Sedation
Confusion
Ocular effects

Question 11

Centrally active drugs that are similar to cyclobenzaprine but less studies include

Answer 11

Carisoprodol (soma) 
Parafon Forte 
Skelaxin 
Robaxin 
Norflex

Question 12

The drugs similar to cyclobenzaprine do what

Answer 12

Relieve acute muscle spasm caused by local tissue trauma or muscle strain
They act primarily at the level of the brain stem

Question 13

What is Carisoprodol (soma)

Answer 13

Scheduled IV drug metabolized to meprobamate (another scheduled IV drug)
Sedatives used as muscle relaxants, but evidence of efficacy w/o sedation is lacking

Question 14

Withdrawal of Carisoprodol and meprobamate after extensive use elicits

Answer 14

physical withdrawal 
anxiety
tremors
muscle twitching 
insomnia
auditory and visual hallucinations 
**So taper slowly over 14 days

Question 15

What is the MOA of Diazepam (Valium)

Answer 15

Acts centrally to increase interneuron inhibition of primary motor afferents in spinal cord
Facilitates GABA-ergic transmission in CNS to activate GABA-a receptors (post-synaptic)
Central sedation
Lasts 12-24 hours, hepatic metabolism

Question 16

Uses for Diazepam include

Answer 16

chronic spasm 2/2 cerebral palsy, stroke, or SCI

Acute spasm 2/2 muscle injury

Question 17

ADE of Diazepam include

Answer 17

Sedation
Antegrade amnesia
Abuse potential
Idiosyncratic reaction: paradoxical hyperexcitable and combative state

Question 18

What is the MOS of Tizanidine

Answer 18

Acts centrally to inhibit reflex motor output from pre and post-synaptic
A2 agonist in spinal cord (lowers BP)
lasts 3-6 hours, renal and hepatic elimination

Question 19

Tizanidine is used for

Answer 19

spasms 2/2 MS, CVA, and ALS

Question 20

ADE of Tizanidine include

Answer 20

weakness
sedation
hypotension

Question 21

How does Dantrolene work

Answer 21

Acts directly on muscles by blocking calcium release channels in SR
Reduced myosin-actin interaction=weakens muscle contraction
lasts 4-6 hours, IV and oral use

Question 22

Dantrolene is used for

Answer 22

IV: malignant hyperthermia
oral: Spasms 2/2 cerebral palsy, SCI, and MS

Question 23

ADE of Dantrolene include

Answer 23

muscle weakness

Question 24

What is the MOA of Botulinum toxin

Answer 24

Cleaves fusion proteins in nerve endings causing flaccid paralysis
Lasts 2-3 months after direct injection into muscle

Question 25

Botulinum toxin is used for

Answer 25

Spasms 2.2 cerebral palsy
MS
overactive bladder
migraine headache

Question 26

ADE of botulinum toxin include

Answer 26

Muscle weakness

Falls