PNP Drug Mechanisms Flashcards
Tetrodotoxin (TTX)
Presynaptic neuromuscular agent
blocks voltage gated Na channels
Mg2+, cations
presynaptic agent
competition/blocker of ca2+ channels
aminoglycosides
presynaptic agent
reduces Ca entry through channels
Note: do not use these antibiotics with myasthenia gravis patients
black widow spider venom
a-latrotoxin
presynaptic agent
adds Ca channels to membrane, leads to barrage and exocytosis creating loss of Ach vesicles and increased surface area (results in transmission block)
botulinum toxin A
presynaptic agent
cleaves SNAP-25 (SNARE complex), reducing calcium sensitivity and preventing secretion
Note: blocks ANS as well, not just muscles
botulinum toxin B
presynaptic agent
cleaves synaptobrevin SNARE protein
hemicholinium
presynaptic agent
interferes with choline uptake, leads to less Ach available for secretion
tubocurarine
postsynaptic non-depolarizing blocker
competitive inhibition of Ach at nicotinic receptors
pancuronium
postsynaptic non-depolarizing blocker
competitive inhibition of Ach, selective for neuromuscular junction
Note: do not use with aminoglycosides (similar to MG)
Note: renal clearance
vecuronium
postsynaptic non-depolarizing blocker
competitive inhibition of Ach, similar to pancuronium but faster action (intermediate duration)
Note: no CV effects, eliminated by liver
rocuronium
postsynaptic non-depolarizing blocker
competitive inhibition of Ach
Note: very rapid onset, similar duration to vecuronium
acetylcholine
post-synaptic depolarizing blocker
nicotinic receptor agonist, can block at high exogenous concentrations
succinylcholine
post-synaptic depolarizing blocker
nicotinic receptor agonist, causes sustained depolarization/desensitization
Notes: rapidly reversible, can cause muscle fasciculations and damage, hydrolyzed by cholinesterases
nicotine
post-synaptic depolarizing blocker
depolarizing blocker at neuromuscular junction
sugummadex
reversal agent of non-depolarizing blocker
encapsulates blockers to eliminate actions (specifically rocuronium, vecuronium)
neostigmine
anti-cholinesterase
binds to cholinesterase to prevent degradation
edrophonium
anti-cholinesterase
binds to cholinesterase, short-acting and rapid onset
physostigmine
anti-cholinesterase
Notes: can cross BBB
pyridostigmine bromide
anti-cholinesterase
neostigmine but long lasting slow release form