Skeletal Muscle Relaxant Meds

Question 1

Which two antispastic agents are not centrally acting?

Answer 1

Dantrolene and Botulinum Toxin A

Question 2

What are the 5 CNS Depressants for antispastics?

Answer 2

Cyclobenzaprine (flexeril)
Carisoprodol (soma)
Metaxalone (skelaxin)
Methocarbamol (robaxin)
Orphenadrine (norflex)

Question 3

What is the 1 central a2 agonist for antispastics?

Answer 3

Tizanidine (zanaflex)

Question 4

What are the 4 GABA agonists for antispastics?

Answer 4

Baclofen
Diazepam (Valium)
Gabapentin
Pregabalin

Question 5

This antispastic is structurally related to TCAs, has a depressant effect on serotonergic neurons, strong anticholinergic/antihistamine properties, and is best used for acute local muscle spasms.

Answer 5

Cyclobenzaprine

Question 6

Especially if used in combination with tramadol, this antispastic has the potential to lower the seizure threshold

Answer 6

Cyclobenzaprine

Question 7

Two most common AEs of cyclobenzaprine?

Answer 7

Drowsiness and serotonin syndrome

Question 8

MIs, cardiac conduction defects, and pts on MAOIs are CIs for this antispastic.

Answer 8

Cyclobenzaprine

Question 9

This antispastic is an analog of diphenhydramine (Benadryl) with antihistamine, anticholinergic, euphoric, and analgesic properties and is used to treat acute muscle spasms associated w/acute MSK conditions.

Answer 9

Orphenadrine, has anticholinergic effects, not used that often

Question 10

This antispastic used to be given for sleep, but it’s addictive and gets metabolized to meprobamate (anxiolytic and sedative effects)

Answer 10

Soma (meprobamate causes dependence, so it has withdrawal symptoms)

Probably shouldn’t be used in pregnancy

Question 11

Newer antispastic that generally depresses the nervous system, used for relief of acute, painful, MSK conditions, and appears to cause less drowsiness than the others.

Answer 11

Metaxalone (skelaxin)

Watch for serotonin syndrome

Question 12

Older antispastic that to suppress spinal polysynaptic reflexes, primary use is to TREAT MUSCLE SPASTICITY ASSOCIATED W/ TETANUS (TOXIN) POISONING

Answer 12

Methocarbamol

Question 13

One of the AEs of this antispastic is urine discoloration (black, brown, or green)

Answer 13

Methocarbamol

Question 14

This central a2 agonist reduces spasticity by increasing presynaptic inhibition of motor neurons…it’s short acting and causes some prominent drowsiness, adjust dose in hepatic/renal impairment.

Answer 14

Tizanidine (zanaflex)

Question 15

GABA-mimetic at the spinal cord level, reduces calcium influx and the release of excitatory transmitters in both the brain and the spinal cord…can also reduce pain by inhibiting the release of substance P

Answer 15

Baclofen

Question 16

This GABA agonist is the anti-spastic/DOC FOR MULTIPLE SCLEROSIS (MS). At least as effective as Valium, w/ less sedation and no loss of strength

Answer 16

Baclofen

Question 17

GABA agonist, increases chloride influx, used as an anxiolytic, spasmolytic, antispasmodic, and antispastic

Answer 17

Diazepam (Valium)

Question 18

Oral form of this drug is used in cerebral palsy, MS, muscle spasms, anxiety disorders, agitation, tremor, delirium, and alcohol withdrawal…risk of dependence/tolerance and a pregnancy class D

Answer 18

Diazepam (Valium)

Question 19

Analog of GABA that does not directly impact GABA receptor, used to treat TONIC-CLONIC SEIZURES, NEUROPATHIC PAIN, POST-HERPETIC NEURALGIA, AND DIABETIC NEUROPATHY (off label)

Answer 19

Gabapentin (Neurontin)

Eliminated really…AEs = drowsiness, fatigue, dizziness

Question 20

GABA derivative similar to gabapentin used to treat partial-onset seizures, neuropathic pain associated with a lot of stuff including diabetic neuropathy and FIBROMYALGIA

Answer 20

Pregabalin (lyrica)

Question 21

This drug, eliminated really…AEs: drowsiness/fatigue greater than gabapentin

Answer 21

Pregabalin (lyrica)

Question 22

Antispastic that interferes with excitation-contraction coupling in the muscle fibers, is the DOC IN THE TREATMENT OF MALIGNANT HYPERTHERMIA (MH)

Answer 22

Dantrolene sodium (Dantriun, Rynodex)

Question 23

Dantrolene is not indicated for skeletal muscle spasm resulting from what type of disorders?

Answer 23

Rheumatic disorders (chorea, rheumatic fever, etc)

Question 24

Between Dantrium and Rynodex, which has the fastest time to admin and which is more expensive?

Answer 24

Rynodex

Question 25

Botulinum toxin type A is MC used for…

Answer 25

Cosmetic application

Question 26

Non-cosmetic clinical use of botulinum toxin

Answer 26

Chronic migraines (2nd line agent), cervical dystonia, blepharospasm

Question 27

What is the antidote to botulinum toxin?

Answer 27

Equine botulinum antitoxin