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Pharmacology > Anticholinesterase drugs > Flashcards

Anticholinesterase drugs Flashcards

1
Q

What are anticholinesterase drugs?

A

There are drugs which inhibit acetylcholinesterase enzyme and prevent the break of acetylcholine at which they manifest and indirect cholinomemetic activity in vivo.

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2
Q

What is the classification of anticholinesterase drugs according to the reversibility?

A
  1. Those with reversible actions
  2. those with irreversible actions
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3
Q

what are the anticholinesterase drugs with reversible actions?

A
  1. simple alcohols like edrophonium
  2. carbamates
    - Physostigmine
    - Neostigmine
    - Pyridostigmine
    - Rivastigmine
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4
Q

what are the anticholinesterase drugs with irreversible actions?

A

They are of a force for organic substances like Dyflos

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5
Q

What is the mechanism of action of edrophonium?

A
  • It reversibly bounds to the anionic center of the enzyme and prevents the binding of acetylcholine to the enzyme.
  • Anticholinesterase drug and enzyme complex doesn’t have covalent bond so they have only short action at which this inhibition is developed due to the diffusion of anticholinesterase drug from this complex and not due to hydrolysis of this complex hence the period of action is 2 to 10 minutes
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6
Q

What is the mechanism of action of carbamates?

A
  • They bound to both anionic and astray centres of the enzyme and they undergo hydrolysis in 2 stages
    first stage of hydrolysis includes the carbonylation of serene of acetylcholinesterase enzyme and the removal of choline
  • the second stage is the removal of carbonyl group from the serine residue under the action of water
    it is more resistant to hydrolysis and takes 30 minutes to six hours
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7
Q

What is the mechanism of action of POS?

A
  • They bound to the esterase center of the enzyme and phosphorylated enzyme doesn’t interact with water orders interact very slowly at which they take 100 or more hours and our visible inhibitors.
  • Phosphorylated enzyme can become aged due to the removal of the alkyl group and it becomes more stable towards hydrolysis
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8
Q

How does the lipophilicity of a drug affect their actions?

A
  • Lipophilic drugs like physostigmine have more muscarinic and central effects like stimulating the vegetative ganglions and their effects on skeletal muscles aren’t obvious.
  • Lipid and soluble drugs like neostigmine and other substances which contain quaternary ammonium have more effect on skeletal muscles and stimulate vegetative ganglions but muscarinic effects are less
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9
Q

describe the effects of anticholinesterase drugs on the body.

A

These drugs can’t penetrate the BBB and don’t have a central effect

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10
Q

what are the effects of anticholinesterase drugs on the eye?

A
  1. Miosis
  2. Spasm of accommodation
  3. decrease of intraocular pressure
  4. lacrimation
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11
Q

what are the effects of anticholinesterase drugs on the CNS?

A
  • In small doses lipid soluble drugs activate the CNS and the desynchronization of EEG occurs
  • in high doses these drugs cause inhibition of C&S
  • in toxic doses they can cause seizures which can end with a coma and respiratory paralysis
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12
Q

what are the effects of anticholinesterase drugs on autonomic ganglia?

A
  • Stimulation of ganglions occur due to direct action on muscarinic receptors
  • high doses because stable depolarization of nicotinic receptors and inhibition of neurotransmission
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13
Q

what are the effects of anticholinesterase drugs on the neuromuscular synapse?

A
  • In high doses they cause stable depolarization of the postsynaptic membrane due to which inhibition of neuromuscular neurotransmission is developed resulting in weakness and paralysis
  • neostigmine can have a direct agonistic activity towards nicotinic receptors which will increase their value as a drug for the treatment of myasthenia gravis
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14
Q

what are the effects of anticholinesterase drugs on the CVS?

A
  • The action on heart muscle is dominant and similar to that of the vagus nerve
  • the decrease of blood pressure is and significant
  • in high doses bradycardia and the fall of blood pressure develops
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15
Q

what are the effects of anticholinesterase drugs on the respiratory system in center?

A

Bronchospasm and stimulation of secretor function of the bronchial glands

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16
Q

what are the effects of anticholinesterase drugs on the GIT?

A

Stimulation of peristalsis and secretion which is developed due to the stimulation of M receptors and intramuscular plexus of intestines

17
Q

what are the effects of anticholinesterase drugs on the Exocrine glands?

A

Stimulation of their secretion

18
Q

what are the effects of anticholinesterase drugs on the Urinary system?

A

Increase in tone of bladder and urethra and increase of urination

19
Q

describe the differences in the pharmacokinetics of different anticholinesterase drugs.

A
  • Carbamates With quaternary ammonium Like Neil stick mean are hardly absorbed from the different surfaces and they’re insoluble in lipids and they don’t penetrate the BBB
  • Carbamates Worcester tree ammonium like those take mean are well absorbed from the skin and mucous membranes, they penetrate BBB and are more toxic compared to the polar carbon mates at which they’re metabolized by cholinesterase.
  • POS are absorbed from the skin and mucous membranes very easily hence they’re very dangerous and are used in agriculture as insecticides
20
Q

what are the usages of edrophonium?

A

It’s short and rapid action is used for the diagnosis of myasthenia gravis

21
Q

what are the usages of neostigmine And pyridostigmine?

A
  1. Treatment of myasthenia gravis
  2. treatment of atony of intestines and urinary bladder
  3. prevention of neuromuscular blockade induced by competitive Myorelaxants
22
Q

what are the usages of physostigmine in?

A
  1. Treatment of glaucoma
  2. it is used to systemically for the prevention of central and peripheral effects caused by overdose of anti muscarinic agents due to its ability to penetrate BBB
23
Q

what are the usages of Dyflos?

A

It is an insecticide and was previously tropically used in ophthalmology as a substance causing miosis.

24
Q

What are the clinical symptoms of anticholinesterase drug intoxication?

A
  1. Lacrimation, salvation, and sweating
  2. inhibition of respiration leading to respiratory insufficiency
  3. irritation and ataxia
  4. miosis
  5. breathlessness
  6. colics
  7. involuntary urination and defecation
  8. decrease of blood pressure and reflex tachycardia
  9. convulsion and death
25
Q

what are some treatments of anticholinesterase drug intoxication? (book notes too for point 6)

A
  1. Fresh air and washing of skin and mucous membranes with three to 5% solution of sodium hydrocarbonate
  2. stomach lavage, forced diuresis, hemosorbtion, hemodialysis, and peritoneal dialysis
  3. Artificial respiration
  4. maintaining blood pressure
  5. prevention of convulsions
  6. usage of specific treatment like atropine and reactivators of cholinesterases like pralidoxime

Pharmacology (11 decks)

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