Pharm Chapter 13 - Skeletal Muscle Relaxants

Question 1

What do Skeletal Muscle Relaxants Treat

Answer 1

1. Spasticity

2. Muscle spasms

Question 2

What is the aim of muscle relaxants?

Answer 2

normalize muscle excitability without a profound effect on muscle function

Question 3

Spasticity

Answer 3

characterized by exaggerated muscle stretch reflex. Rapid lengthening of the muscle invokes strong contraction.

Question 4

Skeletal Muscle Spasms-

Answer 4

increased tension in skeletal muscle after musculoskeletal injury or inflammation.

Question 5

Diazepam

Answer 5

increases inhibitory effect of GABA on alpha receptors in spinal cord to produce inhibition of action potential and state of generalized state of sedation.

Question 6

Polysynaptic Inhibitors:

Answer 6

MOA- decrease alpha motor neuron excitability and therefore cause relaxation of skeletal muscle.
Used in combination with a NSAID
Side effects: drowsiness, dizziness, nausea
Long term use can cause tolerance and physical dependence
Examples:
Carisoprodol (soma)
Cyclobenzaprine (flexeril)
Metaxalone (skelaxin)
Orphenadrine (norflex, antiflex)

Question 7

5 Drugs that manage Spasticity

Answer 7

Baclofen (lioresal)
Diazepam (Valium)
Dantrolene (Dantrium)
Gabapentin (Neurontin)
Tizanidine (Zanaflex)

Question 8

Baclofen (lioresal)

Answer 8

(beta GABA) derivative of endogenous GABA, but slightly different. Decrease firing of alpha neurons with subsequent skeletal muscle relaxation.
Does not cause generalize muscle weakness
Side effect: transient drowsiness.

Question 9

Diazepam (Valium)

Answer 9

Drug of choice in pts with CP

Question 10

Dantrolene (Dantrium)

Answer 10

Only muscle relaxant available that exerts its effect directly on the skeletal muscle itself. Calcium channel blocker effect.
NOT used for muscle spasms caused by musculoskeletal injury.
DOES cause muscle weakness.

Question 11

Gabapentin (Neurontin)

Answer 11

Inhibition in spinal cord to GABA
No effect on endogenous GABA
Use in SCI and MS

Question 12

Tizanidine (Zanaflex)

Answer 12

Binds to the alpha 2 receptors of the spinal cord to prevent firing and excitability of the alpha motor neuron.
Used a lot in headaches and fibromyalgia because of its effects on pain pathways.
Less general muscle weakness

Question 13

Botox

Answer 13

Blocks presynaptic acetylcholine resulting in paralysis of the muscle fibers

Question 14

Skeletal Muscle Relaxers

Answer 14

Can have anticholinergic effects: drowsiness, sedation, blurred vision, delirium, confusion, dry mouth.
Major ones are carisoprodol, cyclobenzaprine, orphenadrine (benadryl)

Question 15

Paralytics

Answer 15

Used to sedate pts. for when intubation is going to be done
Injected systemically
Can affect organs along with muscles
Eliminates gag reflex