PNP Drug Mechanisms

Question 1

Tetrodotoxin (TTX)

Answer 1

Presynaptic neuromuscular agent

blocks voltage gated Na channels

Question 2

Mg2+, cations

Answer 2

presynaptic agent

competition/blocker of ca2+ channels

Question 3

aminoglycosides

Answer 3

presynaptic agent

reduces Ca entry through channels

Note: do not use these antibiotics with myasthenia gravis patients

Question 4

black widow spider venom

a-latrotoxin

Answer 4

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)

Question 5

botulinum toxin A

Answer 5

presynaptic agent

cleaves SNAP-25 (SNARE complex), reducing calcium sensitivity and preventing secretion

Note: blocks ANS as well, not just muscles

Question 6

botulinum toxin B

Answer 6

presynaptic agent

cleaves synaptobrevin SNARE protein

Question 7

hemicholinium

Answer 7

presynaptic agent

interferes with choline uptake, leads to less Ach available for secretion

Question 8

tubocurarine

Answer 8

postsynaptic non-depolarizing blocker

competitive inhibition of Ach at nicotinic receptors

Question 9

pancuronium

Answer 9

postsynaptic non-depolarizing blocker

competitive inhibition of Ach, selective for neuromuscular junction

Note: do not use with aminoglycosides (similar to MG)
Note: renal clearance

Question 10

vecuronium

Answer 10

postsynaptic non-depolarizing blocker

competitive inhibition of Ach, similar to pancuronium but faster action (intermediate duration)

Note: no CV effects, eliminated by liver

Question 11

rocuronium

Answer 11

postsynaptic non-depolarizing blocker

competitive inhibition of Ach

Note: very rapid onset, similar duration to vecuronium

Question 12

acetylcholine

Answer 12

post-synaptic depolarizing blocker

nicotinic receptor agonist, can block at high exogenous concentrations

Question 13

succinylcholine

Answer 13

post-synaptic depolarizing blocker

nicotinic receptor agonist, causes sustained depolarization/desensitization

Notes: rapidly reversible, can cause muscle fasciculations and damage, hydrolyzed by cholinesterases

Question 14

nicotine

Answer 14

post-synaptic depolarizing blocker

depolarizing blocker at neuromuscular junction

Question 15

sugummadex

Answer 15

reversal agent of non-depolarizing blocker

encapsulates blockers to eliminate actions (specifically rocuronium, vecuronium)

Question 16

neostigmine

Answer 16

anti-cholinesterase

binds to cholinesterase to prevent degradation

Question 17

edrophonium

Answer 17

anti-cholinesterase

binds to cholinesterase, short-acting and rapid onset

Question 18

physostigmine

Answer 18

anti-cholinesterase

Notes: can cross BBB

Question 19

pyridostigmine bromide

Answer 19

anti-cholinesterase

neostigmine but long lasting slow release form

Question 20

DFP

Answer 20

anti-cholinesterase

irreversible phosphorylation of esteratic site of acetylcholinesterase

Notes: well absorbed in all routes

Question 21

sarin

Answer 21

anti-cholinesterase

irreversible phosphorylation of esteratic site of acetylcholinesterase

Question 22

parathion

Answer 22

anti-cholinesterase

irreversible phosphorylation of esteratic site of acetylcholinesterase

Notes: metabolized into a toxic form that inhibits ChE

Question 23

malathion

Answer 23

anti-cholinesterase

irreversible phosphorylation of esteratic site of acetylcholinesterase

Notes: slightly safer than malathion (easier metabolism)

Question 24

chlorpyifos

Answer 24

anti-cholinesterase

irreversible phosphorylation of esteratic site of acetylcholinesterase

Question 25

VX

Answer 25

anti-cholinesterase irreversible phosphorylation of esteratic site of acetylcholinesterase Notes: almost impossible to remove, deadliest of nerve gases

Question 26

rivastigmine, galantamine, donepezil, tacrine

Answer 26

anti-cholinesterase cholinesterase inhibitor

Question 27

oximes, pralidoxime

Answer 27

anticholinesterase antagonist remotes phosphorylation from ache to restore cholinesterase activity

Question 28

dantrolene

Answer 28

peripheral muscle relaxant ryanodine receptor blocker, preventing release of Ca

Question 29

methacholine

Answer 29

parasympathomimetic muscarinic receptor agonist

Question 30

bethanechol

Answer 30

parasympathomimetic muscarinic receptor agonist Notes: resistant to hydrolysis by cholinesterases

Question 31

pilocarpine

Answer 31

parasympathomimetic muscarinic receptor agonist Notes: not hydrolyzed by cholinesterases

Question 32

cevimeline

Answer 32

parasympathomimetic muscarinic receptor agonist Notes: only used in Sjogren's

Question 33

atropine

Answer 33

muscarinic receptor blocker competitive inhibitor of Ach at muscarinic receptors Notes: associated with toxicity syndrome

Question 34

homatropine

Answer 34

muscarinic receptor blocker competitive inhibitor of Ach at muscarinic receptors, like atropine but shorter acting

Question 35

scopolamine

Answer 35

muscarinic receptor blocker competitive inhibitor of Ach at muscarinic receptors Notes: causes more CNS depressant effects compared to atropine

Question 36

glycopyrrolate

Answer 36

muscarinic receptor blocker Notes: prevents excessive muscarinic effects after removal of blocker

Question 37

tolterodine

Answer 37

muscarinic receptor blocker Notes: has active metabolite

Question 38

fesoterodine

Answer 38

muscarinic receptor blocker Notes: needs to be metabolized to active version

Question 39

solifenacin

Answer 39

muscarinic receptor blocker like tolterodine but better

Question 40

darifenacin

Answer 40

muscarinic receptor blocker

Question 41

oxybutynin

Answer 41

muscarinic receptor blocker

Question 42

tropicamide

Answer 42

muscarinic receptor blocker ocular effects

Question 43

ipratropium

Answer 43

muscarinic receptor blocker SAMA, bronchiolar dilation, blocks both presynaptic inhibitory and postsynaptics

Question 44

tiotropium

Answer 44

muscarinic receptor blocker LAMA, bronchiolar dilation, more effective than ipratropium (postysnaptics only)

Question 45

norepinephrine

Answer 45

non-selective adrenergic agonist activity: all a, B1, B3 No B2

Question 46

epinephrine

Answer 46

non-selective adrenergic agonist activity: all a and B notes: metabolized by MAO

Question 47

isoproterenol

Answer 47

non-selective adrenergic agonist activity: all B, No a

Question 48

phenylephrine

Answer 48

selective a1 agonist longer duration than epi,, selective but not potent

Question 49

imidazolines

Answer 49

selective a1 agonist long acting Notes: may cause depressant effects in kids