Anticholinesterase and Anticholinergics Flashcards
inhibition of AChE allows for __ ACh to be available
more
the enzyme that hydrolyzes ACh molecules at 300,000 molecules per minute
acetylcholinesterase (AChE)
this MOA of anticholinesterases inhibits AChE by causing carbamylation of AChE or by attaching to the enzyme
enzyme inhibition
this MOA of anticholinesterases causes increased availability of ACh, which in the absence of a nmb can cause contractions
presynaptic effect
this MOA of anticholinesterases causes decreased sensitivity resulting in a blockade effect due to an increased amount of ACh at the NMJ
direct effect on NMJ
these two anticholinesterases “compete” with ACh to be hydrolyzed by the AChE. If these drugs “win” they cause the enzyme to be carbamylated and decrease its ability to hydrolyze ACh
neostigmine and pyridiostigmine
this anticholinesterase attaches to AChE electrostatically to decrease its ability to hydrolyze ACh
edrophonium
causes chemical change in the enzyme and reversibly inhibits its ability to hydrolyze ACh by being hydrolyzed by AChE
neostigmine, pyridostigmine and physostigmine
carbamylation of AChE - reversible inhibition
carbamylated AChE 1/2 life is..
15-30 mins
forms a reversible electrostatic attachment to AChE to inhibit its ability to hydrolyze ACh so ACh can move around and do its business
electrostatic bound - truly reversible inhibition
endrophonium
these from an irreversible complex that must be replaced with generation of NEW enzyme
organophosphate anticholinesterase agents
examples of organophosphase anticholinesterase agents
echothiophate - eye drops
insecticides (dog washer)
nerve gases - think war
neostigmine, pyridostigmine and endrophonium share these chemical properties
have a quaternary ammonium (found on NMB and ACh)
poor lipid solubility
tertiary amine that is lipid soluble and can cross the BBB
physostigmine
Dose 0.06 mg/kg (max 0.07 (peds) and 5 mg)
Onset 7 to 11 mins
elimination 50% renal and 50% plasma esterases and hepatic met
neostigmine
important doses to know RAN
Rubinol 0.015
Atropine 0.030
Neostigmine 0.060
Dose 0.5 to 1 mg/kg
onset 30-60 seconds
elimination is 75% renal
endrophonium (enlon)
dose 0.3 mg/kg
onset 10-20 mins
elimination 75% renal
pyridostigmine (mestinon)
dose 0.5 - 2 mg
onset 5 mins
elimination hepatic and hydrolysis by cholinesterases
physostigmine (antilirium)
used to treat CNS effects of anticholinergic agents, anesthetics, reduces shivering, emergence delirium
physostigmine (antilirium)
what anticholinesterase is better to reverse atracurium
edrophonium
what anticholinesterase is better to reverse vecuronium
neostigmine
deep NMB is reversed better with …
neostigmine (think infusions of atracurium, vecuronium, pancuronium)
once AChE is maximally inhibited, giving more of a anticholinesterase will NOT reverse a NMB
ceiling effect