NMB reversal agents & anticholinergics Flashcards
What type of bond is formed when edrophonium binds to the anionic site on acetylcholinesterase?
a. electrostatic
b. hydrogen
c. covalent
d. ester
a. electrostatic
Acetylcholinesterase terminates the effect of acetylcholine by
hydrolyzing it into choline & acetate
We can reverse the effects of neuromuscular blockers by
giving a drug that inhibits AchE at the neuromuscular junction
AchE inhibitors used to reverse the effects of nondepolarizing NMBs include
edrophonium
neostigmine
pyridostigmine
AchE inhibitors reverse the effects of NMBs in two ways:
enzyme inhibition
presynaptic effects
Pseudocholinesterase is inhibited by
neostigmine & pyridostigmine; therefore, if succinylcholine is given after either, the duration of succinylcholine will be prolonged
AchE inhibiting drugs bind to and inhibit AchE by interacting with these sites in one of three ways:
electrostatic attachment
formation of carbamyl esters
phosphorylation
In what ways does neostigmine bind to the esteratic site of acetylcholinesterase?
carbamyl ester complex
In what way does edrophonium bind to the anionic site of acetylcholinesterase?
electrostatic bond
In what ways does edrophonium bind to the esteratic site of acetylcholinesterase?
hydrogen bond
In what ways does organophosphate bind to the esteratic site of acetylcholinesterase?
phosphorylated enzyme
The primary mechanism of edrophonium is most likely
presynaptic
Examples of competitive inhibition of NMB reversal agents include
edrophonium, neostigmine, pyridostigmine, physostigmine
Examples of non-competitive inhibition of NMB reversal agents include
organophosphates
echothiopate
Which statements regarding anticholinesterase drugs are true?
a. 50% of neostigmine is metabolized by the liver
b. edrophonium + neostigmine has a synergistic effect
c. renal failure necessitates a second dose
d. neostigmine is more potent than pyridostigmine
a. 50% of neostigmine is metabolized by the liver
d. neostigmine is more potent than pyridostigmine
To reduce the risk of cholinergic side effects ______________ is always administered with an acetylcholinesterase inhibitor
anticholinergic drug
_________ is bested paired with edrophonium
atropine
__________ is best paired with neostigmine or pyridostigmine
glycopyrrolate
The deeper the degree of neuromuscular blockade, the_____________ of the acetylcholinesterase inhibitor
longer the onset time
AchE inhibitors have a ________ effect
ceiling effect above which additional drug does not produce a better recovery
Mixing AchE inhibitors produces ___________ effect.
an additive
A TOF ratio <0.9 increases the risk of
airway obstruction, hypoxemia events, and postoperative pulmonary complications
Giving an excessive dose of an AchE inhibitor (beyond what is required for full recovery) can cause
paradoxical muscle weakness
What is the dose of edrophonium?
0.5-1.0 mg/kg
What is the onset of edrophonium?
1-2 min.
What is the DOA of edrophonium?
30-60 min.
What is the metabolism & elimination of edrophonium?
renal 75%
liver 25%
What is the dose of neostigmine?
0.02-0.07 mg/kg
What is the onset of neostigmine?
5-15 min
What is the DOA of neostigmine?
45-90 minutes
What is the metabolism & elimination of neostigmine?
renal 50%
liver 50%
What is the dose of pyridostigmine?
0.1-0.3 mg/kg
What is the onset of pyridostigmine?
10-20 min
What is the duration of pyridostigmine?
60-120 min.
What is the metabolism & elimination of pyridostigmine?
renal 75%
liver 25%
____________ prolongs the DOA for both AchE inhibitors and NMBs
renal failure - no need to adjust the dose of the AchE inhibitor
Do any of the acetylcholinesterase inhibitors pass through the BBB?
only physostigmine- tertiary amine
the rest (edrophonium, neostigmine, and pyridostigmine) do not b/c they are quaternary amines
When compared to adults, antagonism with neostigmine is _______ in infants & children
neostigmine
__________________ reduces the incidence of postoperative shivering.
Physostigmine (40 mcg/kg)
_____________ produces analgesia
Intrathecal neostigmine (50-100 mcg)
Side effects of intrathecal neostigmine include
nausea & vomiting, pruritus, and prolongation of sensory and motor block
List 4 drugs that reduce the incidence of shivering in the PACU?
meperidine
physostigmine
clonidine
dexmedetomidine
Which side effect is LEAST likely to occur after neostigmine administration?
a. bronchospasm
b. mydriasis
c. nausea
d. prolonged QT interval
b. mydriasis (pupil dilation)
AchE inhibitors cause _____________ side effects.
parasympathetic side effects
Cholinergic side effects include
miosis
lacrimation
salivation
bronchoconstriction
bradycardia
emesis
diarrhea
laxation
urination
The mnemonic for cholinergic side effects is
DUMBBELLS
