Anticholinesterases

Question 1

reversible ChE inhibitor

Answer 1

• competitive inhibitor
• form transient complexes with the ChE’s
• blocks access of ACh to AChE active site
• there is only one: Edrophonium

Question 2

carbamates

Answer 2

• competitive substrates of AChE.

- block active site while undergoing slow hydrolysis

Question 3

which drug is preferred for myesthenia gravis and why?

Answer 3

pyridostigmine is preferred over neostigmine because it has a longer duration of action (3-6 hrs) instead of (2-4 hrs)

Question 4

neostigmine

Answer 4

Quarternary amine with short duration (2-4 hrs); drug of choice for paralytic loss of tone in GI tract; standard use in myasthenia gravis
-reversible AChE inh

Question 5

pyridostigmine

Answer 5

Reversible AChE inhibitor; choice for myasthenia gravis

• may be used as pre-treatment for nerve gases
• similar to neostigmine but longer duration of action (3-6 hrs)

Question 6

physostigmine

Answer 6

tertiary amine
-wide angle glaucoma (sometimes used with pilocarpine)
-can enter CNS and reverse effect of atropine and other anti-M drugs
adverse effect- can form cataracts

Question 7

contraindications of myasthenic drugs

Answer 7

• COPD
• asthma
• gastric ulcer

Question 8

irreversible cholinesterase inhibitors

Answer 8

• called organophosphates
• form highly stable covalent phospho intermediates and this bond is effectively irreversible
  - this bond can be strengthened with time, it undergoes “aging”

Question 9

echothiophate

Answer 9

Only clinically useful organophosphate; used in glaucoma

Question 10

malathion

Answer 10

-“pro-drug” insecticide which once activated, undergoes “detox” in mammals via plasma esterases

Question 11

parathion

Answer 11

• potent insecticide pro-drug

- responsible for most poisonings out of all insecticides

Question 12

sarin/soman

Answer 12

-“nerve gases”

Question 13

edrophonium

Answer 13

Simple, competitive cholinesterase inhibitor; blocks access of ACh to AChE active site

• brief duration of action (1-5 min)
• test for myasthenia gravis – rapid IV admin of small dose will result in brief improvement of strength

Question 14

Side effects of acute intoxication of anticE’s

Answer 14

mixture of M, N and CNS

Question 15

symptoms of cholinergic toxidrome

Answer 15

SLUDGE-BAM
salivation/sweating
lacrimation
urination
defecation
GI upset
Emesis
Bradycardia/ bronchoconstriction/ bowel movement
Abdominal cramps/ Anorexia
Miosis

Question 16

M excess in parasymp

Answer 16

bronchospasm
bronchorrhea
miosis
lacrimation
urination
diarrhea
bradycardia
vomiting
salivation
sweating

Question 17

N excess in symp

Answer 17

hypotension (desensitization of Rs on symp ganglia

sweating (also direct M effect)

Question 18

overstim of M and N in CNS

Answer 18

confusion, agitation, coma, respiratory failure, colvusions

Question 19

overstim of N at NMJ

Answer 19

muscle weakness, paralysis, fasiculation

Question 20

Alzheimers disease drugs

Answer 20

Donepezil
Rivastigmine
Galantamine

Question 21

Donepezil

Answer 21

• long duration of action (once a day dosing)

- most perscribed alzheimers drug

Question 22

Rivastigmine

Answer 22

-Similar to Donepezil but twice a day dosing

Question 23

Galantamine

Answer 23

• long acting AChE inhibitor for alzheimers

- mild ChE inh and potent enhancer of N Rs