Apex- NMB reversal agents Flashcards
What kind of bond is formed when edrophonium binds to the anionic site on acetylcholinesterase?
A. Electrostatic
B. Hydrogen
C. Covalent
d. Ester
A. Electrostatic
- achE hydrolyzes ACH into choline and acetate
- this enzyme can be inhibited at the anionic site and/or the esteratic site
- the type of bond that is formed at these sites determines the drugs DOA
- Edrophonium forms an electrostiatic bond at the anionic site & a hydrogen bond at the esteratic site (wonderful)
- these are weak bonds which explain its short DOA
- Neostigmine, pyridostigmine and physostigmine from a carbamyl ester at the esteratic site. These are stronger bonds, which explain why these drugs have a longer DOA.
Explain how NMB are reversed
so acetylcholinesterase usually breaks down ACH
-by inhibiting acetylcholinesterase, more ACH is available at the NMJ to compete and overtake the blocking agent
AchE inhibitors used to reverse the effects of non-depolarizers (3)
- Edrophonium
- Neostigmine
- Pyridostigmine
What would happen if you reverse your patient with neostigmine and then they need an RSI and you need to give sux
The duration of sux wil lbe prolonged and neostigmine (as well as pyridostigmine) inhibit pseudocholinesterase which is needed to break down sux.
T/F- neostigimine, pyridostigmine, and edrophonium all inhibit acetylcholinesterase and pseudocholinesterase
False- edrophonium does NOT inhibit pseudocholinesterase , just acetylcholinesterase
Two ways bey which AchE inhibitors increase the concnetration of Ach at the nicotinic receptor
- Enzyme inhibition
- Presynaptic effects
- AchE inhibitors are thought to stimulate the presynaptic recpetor and cause it to release additional Ach directly + indirectly by increasing concentrations of Ach in the NMJ
How many binding sites does AchE have for ACH?
Two
Edrophonium creates at (electrostatic,hydrogen) bond at the (anionic/esteratic) site on the acetylcholinesterase enzyme
Electrostatic @ Anion site (think anion = a negatively charged ion, so you need electricity to blance it)
Hydrogen bond @ the esteratic site
Which NMB reversal agent works by creating a carbamyl ester complex at the esteratic site of AchE ?
Neostigmine
Which drug non-competitively inhibits ACH by phosphorlation (2)
- echothiopate
- organophosphates
T/F- pyridostigmine is more potent than neostigmine
FALSE - neostigmine is more potent than the pyramids
T/F- the primary mechanism of edrophonium is most likely presynaptic
True
T/F- combining AchE inhibitors produces a synergistic effect
False - additive
_____% of Neostigmine is metabolized in the liver.
50%
Which anticholinergic is best paired with pyridostigmine
glyco (pyramids and neo)
Atropine is best paired with which AchE inhibior?
Edrophonium