Kruse - skeletal muscle relaxants - agents that act on NMJ

Question 1

admin of all nondepolarizing agents

Answer 1

paternal

Question 2

shortest acting drug with most histamine release in nondepolarizing class.
What is notable about combination with AChE inhibitor?

Answer 2

mivacurium

prolong the NM blockade if combined with AChE inhibitor

Question 3

long acting drug in nondepolarizing class that is CI in renal failure

Answer 3

doxacurium

Question 4

MOA of NM blocking drugs

Answer 4

act at NMJ in skeletal muscle at post junctional folds of motor end plates

Question 5

hypotension and tachycardia are AE of which drug in the nondepolarizing class

Answer 5

metocurine

AChR blockade at autonomic glanglia and adrenal medulla, causing hypotension and tachycardia

Question 6

nondepolarizing class + ___antibiotic____ = enhance NM blockade?

Answer 6

aminoglycosides

Question 7

Botulinum toxin, local anesthetics, tetrodotoxin - all do what to nondepolarizing agent?

Answer 7

enhance action

Question 8

Use of nondepolarizing agents in myasthenia gravis does what?

Answer 8

enhances the muscle relaxation

Question 9

Which steroid derivative has ultrashort DOA.

• elimination
• use

Answer 9

Rocuronium - bilary/hepatic elimination and used for jaw/laryngeal mm relaxation before intubation.

Question 10

What drug has this MOA: nAChR agonist with longer effects at NMJ than ACh

Answer 10

succinylcholine

Question 11

Phases and results of succinycholine action. What phase do AChE inhibitors affect?

Answer 11

• Phase 1 - depol MEP making it unresponsive to further impulses –> flaccid paralysis
• Phase 2 - membrane desensitized bc it cannot depol again after repolarizing (**AChE inhibitors work here!)

Question 12

tansient mm fasciculations are caused by

Answer 12

succinylcholine

AChE inhibitors

Question 13

what reverses actions of succinylcholine?

Answer 13

plasma cholinesterases

Question 14

CI of succinylcholine

Answer 14

• malignant hyperthermia

- BLACK BOX: cardiac arrest

Question 15

tx for malignant hyperthermia

Answer 15

dantrolene - a mm relaxant that inhibits RyR calcium channels, impairing muscle contraction

Question 16

MOA of__: cleaves SNAR complex, blocking ACh release from vesicle

Answer 16

botulinum toxin

Question 17

Overall MOA of acetylcholinesterase inhibitors

Answer 17

decrease AChE levels, thus increasing ACh levels throughout hte body

Question 18

tertiary/uncharged AChE inhibitors (5)
Do they cross BBB?

which agent has high heaptotoxic agents?

Answer 18

donepezil*
galantamine*
physostigmine
rivastigmine*
tacrine*

Yes, do cross BBB = toxic.

*dementia

Question 19

quaternary/charged AChE inhibitors (5)

Do they cross BBB?

Answer 19

ambenonium
echothiophanate
edrophonium
neostigmine
pyridostigmine

No, do not cross BBB = safer

Question 20

Which AChE inhibitors are reversible?

Answer 20

the carbamic acid esters - noncovalent

ambenoium, neostigmine, physostigmine, pyridostigmine

Question 21

Antidote for overexposure to organophosphate

Answer 21

pralidoxime and benzodiazepine - give pralidoxime BEFORE aging has occurred.

Question 22

AChE inhibitors used for MG

Answer 22

ambenoium, neostigmine, pyridostigmine

Question 23

prophylaxis for organophosphate poisoning

Answer 23

pyridostigmine

Question 24

acute AChE inhibitor intoxication - sx

Answer 24

mAChR stimulation sx: miosis, salivation, sweating, bronchial constriction, V/D
-Earliest sx: GI, then sweating and muscle fasciculations

Question 25

tx of acute AChE inhibitor intoxication/cholinergic poisoning. Need to coadminister with___.

Answer 25

atropine (mAChR antagonist)

coadminister with pralidoxime

Question 26

use what class to tx dementia?

Answer 26

AChE inhibitor

Question 27

use what class to treat glaucoma?

Answer 27

AChE inhibitor - reducing intraocular pressure via mAChR stimulation that facilitates aqueous outflow

Question 28

drug used to reverse anticholinergic overdose (sx: cutaneous vasodilation, anhidrosis, delirium, hallucinations, reduced urination, anhidrotic hyperthermia –> SNS like effects)

Answer 28

Physostigmine

reverses nondepolarizing NM blocking drugs by increasing ACh

Question 29

do not coadminister AChE inhibitors with ____ in pts with MG

Answer 29

systemic corticosteroids

Question 30

Atropine is ineffective at what receptors?

Answer 30

nAChR

Question 31

MOA of ____ : antagonist of the (NMDA) type of glutamate receptors. Why useful in Alzheimer’s Disease?

Answer 31

memantine

Pathologic or excessive receptor activation (AD), prevents
Mg from reentering and blocking the channel pore resulting in a chronically open state and excessive calcium influx
Memantine binds to the intra-pore Mg site, but with longer dwell time, and thus functions as an effective receptor blocker only under conditions of excessive stimulation. Does not affect normal neurotransmission.