Pharm - Muscle Relaxants

Question 1

compare MOA between non-depolarizing and depolarizing neuromuscular blocking agents

Answer 1

non-depolarizing: antagonists of nAChR

depolarizing: excess of depolarizing agonist (e.g. excess acetylcholine)

Question 2

list the long acting non-depolarizing neuromuscular blocking agents

Answer 2

doxacurium, pancuronium, pipecuronium

Question 3

list the intermediate acting non-depolarizing neuromuscular blocking agents

Answer 3

atracurium, cisatracurium, rocuronium, vecuronium

Question 4

list the short acting non-depolarizing neuromuscular blocking agents

Answer 4

mivacurium

Question 5

how are non-depolarizing neuromuscular blocking agents reversed

Answer 5

addition of acetylcholine using an AChE inhibitor

Question 6

adverse effects non-depolarizing neuromuscular blocking agents

Answer 6

• some produce histamine –> bronchospasm, hypotension, bronchial and salivary secretion
• large doses tubocurarine –> acetylcholine receptor blockade at autonomic anglia and adrenal medulla –> fall in blood pressure and tachycardia

Question 7

drug-drug interactions with non-depolarizing neuromuscular blocking agents

Answer 7

inhaled anesthetics potentiate the neuromuscular blockade

antibiotics (aminoglycosides)

other agents that block signaling at NMJ (tetrodotoxin, local anesthetics, botulinum toxin)

Question 8

which inhaled anesthetic has the worse drug-drug interaction with non-depolarizing neuromuscular blocking agents

Answer 8

isoflurane

Question 9

in what patients is there enhancement of the effects of non-depolarizing neuromuscular blocking agents

Answer 9

• elderly pts with reduced hepatic and renal function

- pts with myasthenia gravis

Question 10

what patients are resistant to non-depolarizing neuromuscular blocking agents

Answer 10

pts with severe burns and those with upper motor neuron dz

Question 11

describe phase I and phase II of succinylcholine action

Answer 11

phase I: activates nAChR –> muscle contraction –> membranes stay depolarized and unresponsive to subsequent impulses –> flaccid paralysis results

phase II: continued exposure to succinylcholine –> membrane becomes re-polarized –> membrane unable to de-polarize b/c desensitization

Question 12

indications succinylcholine

Answer 12

rapid sequence induction and quick procedures

Question 13

adverse effects succinylcholine

Answer 13

CV: arrhythmias, negative inotropic and chronotropic effects

metabolic: hyperkalemia

CNS: increase intraocular pressure, muscle pain

Question 14

contraindications succinylcholine

Answer 14

fmhx malignant hyperthermia

myopathies with elevated CPK

Question 15

black box warning for succinylcholine

Answer 15

acute rhabdomyolysis w/ hyperkalemia followed by ventricular dysrhythmias, cardiac arrest, and death

**seen in children w/ undiagnosed skeletal muscle myopathy

Question 16

drug-drug interactions succinylcholine

Answer 16

volatile anesthetics –> malignant hyperthermia

antibiotics

Question 17

what are the three subgroups of acetylcholinesterase inhibitors

Answer 17

alcohols, carbamic acid esters, organophosphates

Question 18

compare the duration of action between the acetylcholinesterase inhibitors

Answer 18

alcohols: 2-10 minutes

carbamic acid esters: 30m-8hours

organophosphates: bind covalently and reversal of binding requires rapid administration of pralidoxime

Question 19

tx for myasthenia gravis

Answer 19

pyridostigmine, neostigmine, ambenonium

Question 20

the edrophonium test is used to test for

Answer 20

myasthenia gravis

Question 21

what all are AChE inhibitors indicated for

Answer 21

1) myasthenia gravis
2) reversal of pharmacologic paralysis
3) glaucoma
4) dementia
5) antidote

Question 22

in what conditions are AChE inhibitors used for reversal of pharmacological paralysis

Answer 22

paralytic ileus

atony of urinary bladder

congenital megacolon

Question 23

drug-drug interactions with AChE inhibitors

Answer 23

non-depolarizing neuromuscular blocking agnets

succinylcholine (AChEI enhances phase I and antagonizes phase II)

cholinergic agonists (AChEI enhances them)

beta blockers (AChEI enhances bradycardia)

Question 24

treatment for AChE inhibitors overdose

Answer 24

atropine

cholinesterase regenerators are administered to regenerate AChE at the NMJ

Question 25

what is the cholinesterase regenerator used to regenerate AChE at the NMJ

Answer 25

pralidoxime

Question 26

MOA baclofen

Answer 26

GABA-A agonist

Question 27

adverse effects baclofen

Answer 27

drowsiness, increased seizure activity in epileptic pts, vertigo, dizziness, psych problems, insomnia, slurred speech, ataxia

Question 28

adverse effects carisoprodol

Answer 28

dizziness and drowsiness

Question 29

metabolism carisoprodol

Answer 29

CYP2C19

Question 30

MOA chlorzoxazone

Answer 30

depresses polysynaptic reflexes in spinal cord

Question 31

MOA cyclobenzaprine

Answer 31

reduces tonic somatic motor activity by influencing alpha and gamma motor neurons

Question 32

metabolism cyclobenzaprine

Answer 32

CYP450

Question 33

adverse effects cyclobenzaprine

Answer 33

drowsiness, dizziness, xerostomia (dry mouth)

Question 34

MOA tizanidine adverse effects

Answer 34

alpha 2 agonist drowsiness, hypotension, dry mouth, muscle weakness

Question 35

MOA dantrolene

Answer 35

inhibition of RyR --> blocks release of Ca2+ through sarcoplasmic reticulum --> impairs muscle contraction

Question 36

side effects dantrolene

Answer 36

muscle weakness, sedation

Question 37

indications dantrolene

Answer 37

treats spasticity associated with upper motor neuron dzs malignany hyperthermia

Question 38

MOA botulinum toxin

Answer 38

cleaves component of SNARE complex involved in exocytosis --> prevents release of ACh

Question 39

clinical uses botulinum toxin

Answer 39

strabismus, blepharospasm, chronic migraine, cervical dystonia

Question 40

indications and MOA azathioprine

Answer 40

RA and MS antagonizes purine metabolism and inhibits synthesis of DNA, RNA, and proteins

Question 41

indications and MOA dalfampridine

Answer 41

MS K+ channel blocker --> delays re-polarization and prolongs duration of action potentials

Question 42

indications cyclophosphamide

Answer 42

MS

Question 43

indications and MOA glatiramer acetate

Answer 43

MS induces and activates T-lymphocyte suppressor cells specific for a myelin antigen

Question 44

MOA interferons

Answer 44

act on BBB by interfering with T cell adhesion to the endothelium by binding to VLA-4 on T cells, or by inhibited T cell expression of MMP

Question 45

indications and MOA mitoxantrone

Answer 45

intercalates into DNA resulting in cross-links and strand breaks MS

Question 46

indications and MOA natalizumab

Answer 46

monoclobal antibody against alpha-4 subunit of integrin molecules --> blocks integrin association with vascular receptors, limiting adhesion and transmigration of leukocytes MS