NMJ pharm

Question 1

Lidocaine

Answer 1

Blocks VSSC on pre-synaptic neuron

Question 2

Botulinum toxin

Answer 2

lyses synaptobrevin at NMJ preveting vesicle fusion and ACh release - producing flaccid paralysis

Question 3

Black widow venom

Answer 3

forms pores in terminal membranes allowing excess caclium influx - explosive release of ACh at NMJ

Question 4

Tetanus toxin

Answer 4

lyses synaptobrevin after the toxin has been transported in retrograde fashion to spinal cord synapses - there it acts to block release of GABA - causing failure of motor reflex inhibiton and excessive spastic contractions -

Question 5

Curare

Answer 5

competetive antagonist of nicotinic receptor at NMJ –> flaccid

Question 6

Succinylcholine

Answer 6

agonist of nicotninc NMJ - flaccid - depolarization inhibition

Question 7

Neostigmine / nerve gas

Answer 7

AChE inhibitor
Therapeutic doses improve strength
Toxic doses - depolarization block

Question 8

Rocuronium and Atracurium

Answer 8

NM blocking agent - competetive antagonist
surmountable with AChE inhibitors
muscle depolarizable with K+ and electrical stimuli

Question 9

Succinylcholine

Answer 9

Depolarizing blocking agent
not surmountable with AChE inhibitor - rather potentiated
flaccid

Question 10

Pancuronium

Answer 10

NM blocker paralyzes respiratory muscles - used in lethal injection

Question 11

Side effects of competitive antagonists?

Answer 11

histamine release, effect on ganglia and muscarinic

Question 12

side effects of succinylcholine

Answer 12

hyperkalemia / increased intraocular pressure

Question 13

NMJ blocker overdose treatment?

Answer 13

Edrophonium and neostigmine - only non-depolarizing - would worsen depolarizing

Question 14

Cholinesterase inhibtors?
Short
Long
Irreversible

Answer 14

Short - edrophonium
Long - neostigmine
Irreversible - organophosphates / insecticides / nerve gas / echothiophate

Question 15

Cholinesterase reactivator?

Answer 15

Pralidoxime reactivates cholinesterase that has been inactivated by irreversible inhibitors

Question 16

used to treat MG

Answer 16

Edrophonium / neostigmine

Question 17

used to correct neuromuscular blockade from non-depolarizing agents

Answer 17

neostigmine / edrophonium

Question 18

Adverse reactions to organophosphates?
@ muscarinic?
@ nicotinic

Answer 18

muscarinic = BB SLUDGE
nicotinic = MATCH

Question 19

BBSLUDGE

Answer 19

toxicities of muscarinic receptor

bradycardia
bronchoconstriction/bronchochorrhea
salivation/lacrimation/urination/defecation/GI/miosis(constriction)

Question 20

MATCH

Answer 20

Nicotinic toxicity

Muscle weakness/fasciuculations
adrenal medulla activity increase
tachycardia 
cramping
hypertension

Question 21

Pralidoxime

Answer 21

antidote to organophosphate (AChEI)

Question 22

Atropine

Answer 22

muscarinic receptor antagonist - fights with SLUDGE

Question 23

Diazepam

Answer 23

treats convulsions from NMJ toxicity

Question 24

Cholinergic crisis

Answer 24

paradoxical weakening seen with AChEIs - possibly due to depolarization blockade at high doses - distinguished from myasethenic crisis with Tensilon (edrophonium)