skeletal muscle relaxants Flashcards
(26 cards)
tubocurarine
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
atracurium
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
cisatracurium
INTERMED ACTING
benzylisoquinolines
non-depolarizing blocker
forms less laudanosine and causes less histamine release
REPLACED atracurium
mivacurium
SHORT ACTING (only one)
benzylisoquinolines
non-depolarizing blocker
hydrolyzed by butyrylcholinesterase
pancuronium
LONG ACTING
ammonio steroids
non-depolarizing blocker
AE: mod tachycardia d/t blockade of M2
rocuronium
INTERMED ACTING
ammonio steroids
non-depolarizing blocker
most rapid == used for rapid sequence intubation
vecuronium
INTERMED ACTING
ammonio steroidsnon-depolarizing blocker
succinylcholine
only depolarizing blocker = 2 ach molecules bound
very short duration b/c of butyrylcholinesterse hydrolysis
remember butrylchoinesterase polymporphism = prolonged NM blockade
MOA - nondepolarizing blockers
competitive antagonists = overcome with inc acetylcholine (via AchE-I)
MOA - depolarizing blockers
activates nicotinic receptor depolarizes junction
causes fasiculations
not metabolizes by AchE
–> flaccid paralysis
rapid onset - short duration
NM blockers
all contain quarternary groups = doesn’t cross BBB
inactive if given PO
half life vs kidney/liver excretion
kidney = longer t 1/2 liver = shorter t 1/2
benzylisoquinolones AE
hypotension d/t histamine release and slight ganglionic blockade (only with tubocurarine)
no effect on M2 receptors
ammonio steroids AE
produce tachycardia d/t blockade of muscarinic receptors == arrhythmias
no ganglion blockade
tubocurarine AE
ganglion blockade = hypotension and tachycardia
release histamine
succinylcholine AE
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
drugs that enhance NM blockade
inhaled anesthetics
aminoglycosides
tetracyclines
aging and disease vs drug response to NM blockers
MG = inc NM blockade
adv age = prolongs blockade
severe burns and UMN dz = resistant to nondepolarizing relaxants
depolarizing blockers contraindications
hx malignant hyperthermia or myopathies
burns
trauma
denervation of skeletal muscle
UMN injury
reverse nondepolarizing NM blockade
AchE-I
atropine and glycopyrrolate are given to prevent bradycaria
spasmolytic drugs categories:
1) for chronic spasm
a: act in CNS
b: act directly on muscle
2) acute spasm
drugs that act in CNS as tx for chronic spasms
diazepam: agonist at GABA(a)
baclofen: agonist at GABA(b)
tizanidine: alpha2 agonist in CNS
baclofen
agonist at GABA(b)
used for chronic spasms tx
tizanidine
alpha2 agonist in CNS
used for chronic spamsms
