skeletal muscle relaxants

Question 1

tubocurarine

Answer 1

LONG ACTING

benzylisoquinolines
non-depolarizing blocker

may release histamine - give with antihistamine

may also block nicotinic receptors in ANS and adrenal medulla – hypotension and tachycardia

Question 2

atracurium

Answer 2

INTERMED ACTING

benzylisoquinolines
non-depolarizing blocker

forms metabolite = laudanosine - may cause hypotension and seizures
(replaced by cisatracurium)

no inc in half life in pt with renal failure

Question 3

cisatracurium

Answer 3

INTERMED ACTING

benzylisoquinolines
non-depolarizing blocker

forms less laudanosine and causes less histamine release

REPLACED atracurium

Question 4

mivacurium

Answer 4

SHORT ACTING (only one)

benzylisoquinolines
non-depolarizing blocker

hydrolyzed by butyrylcholinesterase

Question 5

pancuronium

Answer 5

LONG ACTING

ammonio steroids
non-depolarizing blocker

AE: mod tachycardia d/t blockade of M2

Question 6

rocuronium

Answer 6

INTERMED ACTING

ammonio steroids
non-depolarizing blocker

most rapid == used for rapid sequence intubation

Question 7

vecuronium

Answer 7

INTERMED ACTING

ammonio steroidsnon-depolarizing blocker

Question 8

succinylcholine

Answer 8

only depolarizing blocker = 2 ach molecules bound

very short duration b/c of butyrylcholinesterse hydrolysis

remember butrylchoinesterase polymporphism = prolonged NM blockade

Question 9

MOA - nondepolarizing blockers

Answer 9

competitive antagonists = overcome with inc acetylcholine (via AchE-I)

Question 10

MOA - depolarizing blockers

Answer 10

activates nicotinic receptor depolarizes junction

causes fasiculations

not metabolizes by AchE

–> flaccid paralysis

rapid onset - short duration

Question 11

NM blockers

Answer 11

all contain quarternary groups = doesn’t cross BBB

inactive if given PO

Question 12

half life vs kidney/liver excretion

Answer 12

kidney = longer t 1/2
liver = shorter t 1/2

Question 13

benzylisoquinolones AE

Answer 13

hypotension d/t histamine release and slight ganglionic blockade (only with tubocurarine)

no effect on M2 receptors

Question 14

ammonio steroids AE

Answer 14

produce tachycardia d/t blockade of muscarinic receptors == arrhythmias

no ganglion blockade

Question 15

tubocurarine AE

Answer 15

ganglion blockade = hypotension and tachycardia

release histamine

Question 16

succinylcholine AE

Answer 16

activates all autonomic cholinoreceptors

nicotinic = muscle pain
muscarinic = bradycardia

histamine release

d/t contractions at beginning:
hyperkalemia
increased intraocular pressure
inc intragastric pressure

malignant hyperthermia

NO CNS effects = no BBB penetration

Question 17

drugs that enhance NM blockade

Answer 17

inhaled anesthetics
aminoglycosides
tetracyclines

Question 18

aging and disease vs drug response to NM blockers

Answer 18

MG = inc NM blockade

adv age = prolongs blockade

severe burns and UMN dz = resistant to nondepolarizing relaxants

Question 19

depolarizing blockers contraindications

Answer 19

hx malignant hyperthermia or myopathies

burns

trauma

denervation of skeletal muscle

UMN injury

Question 20

reverse nondepolarizing NM blockade

Answer 20

AchE-I

atropine and glycopyrrolate are given to prevent bradycaria

Question 21

spasmolytic drugs categories:

Answer 21

1) for chronic spasm
a: act in CNS
b: act directly on muscle

2) acute spasm

Question 22

drugs that act in CNS as tx for chronic spasms

Answer 22

diazepam: agonist at GABA(a)
baclofen: agonist at GABA(b)
tizanidine: alpha2 agonist in CNS

Question 23

baclofen

Answer 23

agonist at GABA(b)

used for chronic spasms tx

Question 24

tizanidine

Answer 24

alpha2 agonist in CNS

used for chronic spamsms

Question 25

botulinum toxin

Answer 25

act on skeletal muscle

for spastic disorders/cerebral palsy

Question 26

drugs for acute spasm

Answer 26

centrally acting

relief of acute muscle spasm by trauma

cyclobenzaprine = prototype

AE: antimuscarinic side effects