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54 Cards in this Set

  • Front
  • Back
acetylcholinesterase (AChE)is found where?
throughout the body
two primary forms of AChE
1) ture AChE
2) pseudocholinesterase (or plasma cholinesterase or butyrylcholinesterase)
true AChE is found on?
on RBC and on the pre and post synaptic memb. of cholinergic transmission sites
pseudocholinesterase is found in?
in the plasma and many other sites throughout the body
function of AChE?
to destroy Ach and prevent overstimulation of cholinergic receptors
acetylcholinesterase inhibitors (AChE-I's)
blodk this enzymatic degradation of Ach by AchE
How AChE-I act in the ANS?
as parasympathomimetics
How AChE-I act in the somatic system?
as neuromuscular stimulants
use of AChE-I
insecticides
military "war gas" agents
2 classifications of AChE-I
1) reversible agents
2) irreversible agents
reversible agents
do not permanently bind to AChE
irreversible agents
organophosphates (OP)
form long-term or permanent covalent bonds to the serine esteratic site
very toxic
aging process
the covalent bond is further strengthened with time as an 'R' group on the phosphoryl group splits off
half-aging times
different OP's have different half-aging times
most toxic compound - minutes
less toxic compound - days
tx for OP poisoning
Atropine
Pralodoxime (2-PAM, Protopam)if the attached OP has not yet 'aged'
symptomology of AChE-I toxicity
salivation
lacrimation
urination
defecation (SLUD)
sweating
miosis
irriversible agents
1) Echothiophate (Phospholine)
2) Malathion (Ovide)
Echothiophate
Phospholine
member of OP class
use of Echothiophate
ophthalmic miotic agent used for glaucoma and dx
Echothiophate; great care must be used in?
asthmatic and cardiac pt
long-term use of Echothiophate may lead to?
cataract formation
Malathion
Ovide
member of OP class, but least human toxic
very potent insecticide
use of Malathion
as topical agent (lotion, shampoo) for the tx of external parasites, including head lice
Malaoxon
active form of Malathion
toxic if ingested or pulmonary aspirated
Malathion poisoning is treated with?
atropine and pralidoxime
Reversible agents
1) Physostigmine
2) Neostigmine
3) Pyridostigmine
4) Edrophonium
5) Tacrine
6) Donepezil
7) Rivastigmine
8) Galantamine
Physostigmine
Eserine, Antilirium
reversible
isolated from the Calabar bean, used as an ordeal poison
tertiary compounds - cross BBB better than neostigmine (guat)
use of Physostigmine
open-angle glaucoma
Alzheimer's diseases with limited success
action of Physostigmine
potentiates the effects of Ach at peripheral nicotinic and muscarinic sites, and in the CNS mainly at muscarinic sites
normal response to parenteral administration of Physostigmine
increased skeletal muscle tone
increased GI tone and motility
bradycardia
sweat and salivary gland stimulation
bronchoconstriction
miosis
decreased IOP
How Physostigmine decrease IOP?
by widening the trabecular network, which allows increased outflow of aqueous humor
Physostigmine at high doses
acts directly at neuromuscular and ganglionic nicotinic receptors as a depolarizing blocker
Neostigmine
Prostigmine
quat
use of Neostigmine
treat acute episodes of MG and dx of MG (edrophonium is preferred for dx due to short half life)
antagonizing the effects of non-depo. NMB
tx of post-op urinary retention and abd. distention
Pyridostigmine
Mestinon
quat
poor oral absorption
use of Pyridostigmine
tx of MG
Edrophonium
Tensilon
only parenteral form available due to *very short duration*
onset of effect is very rapid
quat
use of Edrophonium
drug of choice for dx of MG
for accessing potential benefits/risks of AChE-I therapy
post-op non-depo. reversal
Edrophonium with Atropine
used to tx the respiratory depression seen following curare poisoning
Edrophonium; muscarinic effect?
few muscarinic effects are seen in challenge dosing due to the short duration of action
Tacrine
Cognex
use of Tacrine
1st drug approved to treat Alz. disease to improve cognitive function, but no proof that use will show the progression of the disease
actions of Tacrine
similar to donepezil, but there are more peripheral effects seen
potential for hepatotoxicity
Tacrine inhibits
both true AChE and pseudo ChE almost equally
oral administration of Tacrine
high first pass metabolism seen orally (up to 95 %)
food can decrease absorption 30% (give on an empty stomach)
Donepezil
Aricept
piperidine type reversible ChE-I
high affinity for CNS cholinesterase
use of Donepezil
for mild to moderate Alz. disease
not prolong the course of the disease
Donepezil; hepatotoxicity?
not possess the hepatotoxicity risk seen with Tacrine, and it has fewer peripheral effects
selectivity of Donepezil
more selective for true AChE than Tacrine
oral absorption of Donepezil
well absorbed (100%)
metabolism of Donepezil
via P450 system, which converts Donepezil into two active and two inactive metabolites
half life of effect of the parent compound and active metabolites combined
approximately 70 hrs
Rivastigmine
Exelon
reversible
treat Alz. disease
improve thinking adn memory
Galantamine
Reminyl
treat cognitive loss due to Alz. disease
acts as reversible, competitive antagonist of AChE