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PCM Exam 2 Pharm > CHOLINERGIC AGONISTS & ANTAGONISTS 1 > Flashcards

CHOLINERGIC AGONISTS & ANTAGONISTS 1 Flashcards

1
Q

What are the direct effects of ACh on the CARDIOVASCULAR SYSTEM?

A

DIRECT EFFECTS OF ACETYLCHOLINE

  • Vasodilation (M3 effect).
  • Decrease in cardiac rate (M2 effect).
  • Decrease in rate of conduction in the SA and AV nodes (M2 effect).
  • Decrease in force of contraction (M2 effect).
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2
Q

What effect does a low dose of ACh have on the CARDIOVASCULAR system?

A

• IV injection of a small dose of acetylcholineproduces a fall in blood pressure due to vasodilation (M3 effect) usually accompanied by
reflex tachycardia.

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3
Q

What effect does a large dose of ACh have on the cardiovascular system?

A

• Larger doses of acetylcholine cause vasodilation, a fall in blood pressure (M3 effect) and bradycardia (M2 effect).

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4
Q

What are someone of the effects of ACh on various organ systems?

A
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5
Q

What occurs If muscarinic effects are blocked
by a muscarinic antagonist such as
atropine?

A

large doses of acetylcholine produce nicotinic effects:

  • Increase in blood pressure and vasoconstriction
  • These effects are due to stimulation of sympathetic ganglia and release of epinephrine from the adrenal medulla.
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6
Q

what are the CHOLINE ESTERS?

A

• Acetylcholine • Methacholine • Carbachol • Bethanechol

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7
Q

What are CHOLINE ESTERS and what is their effects?

A
  • Choline esters are quaternary ammoniums.
  • Poorly absorbed and poorly distributed into the CNS.

• They differ in their susceptibility to hydrolysis by
cholinesterase.

  • Acetylcholine is very rapidly hydrolyzed.
  • Methacholine, carbachol and bethanechol are more resistant to hydrolysis by cholinesterase.
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8
Q

ACETYLCHOLINE uses?

A

• Used to obtain rapid miosis after delivery of the lens in cataract surgery and other procedures where rapid miosis is required.

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9
Q

What is BETHANECHOL function and uses?

A

• Muscarinic agonist.

USES :

  • Postoperative and postpartum urinary retention.
  • Atony of the urinary bladder.
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10
Q

What is CARBACHOL function and uses?

A

• Both muscarinic and nicotinic agonist.

USES:

  • Miosis during surgery.
  • Reduces intraocular pressure after cataract surgery.
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11
Q

What is METHACHOLINE function and uses?

A

• Muscarinic agonist.

USES:

• Diagnosis of bronchial airway hyperreactivity in subjects who do not have clinically apparent asthma.

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12
Q

What are the naatural alkaloids?

A

• PILOCARPINE • NICOTINE

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13
Q

What category does PILOCARPINE fall into and whats its effect/uses?

A

NATURAL ALKALOIDS

  • Partial muscarinic agonist.
  • Tertiary amine
  • Stable to hydrolysis by acetylcholinesterase.

Uses: Second line agent for open angle glaucoma. • Management of acute angle-closure glaucoma. • Treatment of dry mouth due to radiotherapy for

cancer of head and neck. • Treatment of dry mouth caused by Sjogren’s
Syndrome.

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14
Q

What category does NICOTINE fall into and whats its effect/uses?

A

NATURAL ALKALOIDS

  • Tertiary amine.
  • Selective agonist of the nicotinic receptor.
  • Depending on the dose, nicotine depolarizes autonomic ganglia, resulting first in stimulation and then in paralysis.
  • Low doses: ganglionic stimulation by depolarization.

CV system: Mainly sympathomimetic effects. ncrease in HR and BP due to catecholamine release from nerve terminals and adrenal medulla.

  • GI & urinary tracts: Mainly parasympathomimetic effects: nausea, vomiting, diarrhea, voiding of urine.
  • Secretions: Stimulation of salivary and bronchial secretions.
  • High doses: ganglionic blockade and neuromuscular blockade.

NICOTINE: ACUTE POISONING

mental confusion and weakness. • The blood pressure falls, the pulse is weak. • Death may occur from paralysis of respiratory muscles and/or central respiratory failure.

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15
Q

What are the ANTICHOLINESTERASES

A
  1. Edrophonium
  2. Carbamates
    • Physostigmine
    • Neostigmine
    • Pyridostigmine
  3. Organophosphates
    • Echothiophate
    • Parathion & Malathion
    • Sarin
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16
Q

How does Edrophonium work?https://www.brainscape.com/decks/7152716/cards/new

A

binds reversibly to the active site of the enzyme. The enzyme-inhibitor complex
doesn’t involve a covalent bond and is short-lived.

  • Quaternary ammonium.
  • Does not enter CNS.

USES • Used in diagnosis of myasthenia gravis. Edrophonium IV leads to rapid increase in muscle strength. • Used to reverse the neuromuscular block
produced by non-depolarizing muscular blockers.

17
Q

How does Carbamates work as an ANTICHOLINESTERASES?

A

• Carbamates form a covalent bond with the
enzyme.

18
Q

How does Organophosphates work as an ANTICHOLINESTERASES?

A

phosphorylate the enzyme. The covalent bond formed is extremely stable and hydrolyzes very slowly.

• The phosphorylated enzyme may undergo a process called ageing where it strengthens the phosphorous-
enzyme bond.

Types: ECHOTHIOPHATE, INSECTICIDES: MALATHION PARATHION, SARIN• Among the most potent synthetic toxic agents known

19
Q

How does ANTICHOLINESTERASES cause its ORGAN SYSTEM EFFECTS

CNS

EYE, RESPIRATORY TRACT, GI TRACT & URINARY TRACT

CARDIOVASCULAR SYSTEM

THE NEUROMUSCULAR JUNCTION

A

CNS: • In low concentrations liposoluble cholinesterase inhibitors cause CNS activation. • In higher concentrations they cause convulsions,coma and respiratory
arrest.

EYE, RESPIRATORY TRACT, GI TRACT & URINARY TRACT: effects of cholinesterase inhibitors are similar to the effects of the direct-acting cholinomimetics

CARDIOVASCULAR SYSTEM: • Modest bradycardia • Fall in cardiac output • Increased vascular resistance • Increase in blood pressure. Toxic doses of cholinesterase inhibitors cause marked bradycardia, significant decrease of
cardiac output and hypotension.

THE NEUROMUSCULAR JUNCTION • Cholinesterase inhibitors increase strength of
contraction. • Useful to reverse action of nondepolarizing neuromuscular blockers. • Useful in myasthenia gravis.

20
Q

How does PHYSOSTIGMINE work?

A
  • Tertiary amine.
  • Can enter and stimulate CNS.

USES • Treatment of overdoses of anticholinergic drugs.

21
Q

What AChE INHIBITORS USED IN ALZHEIMER DISEASE?

A

use of centrally acting acetylcholinesterase inhibitors.

  • Donepezil
  • Rivastigmine
  • Galantamine
22
Q

How does NEOSTIGMINE work?

A
  • Quaternary ammonium.
  • Does not enter CNS.

USES • Postoperative urinary retention. • Reversal of effects of non-depolarizing
neuromuscular blockers after surgery. • Treatment of myasthenia gravis

23
Q

How does PYRIDOSTIGMINE work?

A
  • Quaternary ammonium.
  • Does not enter CNS.

USES • Treatment of myasthenia gravis.

24
Q

What is the REACTIVATOR OF AChE: PRALIDOXIME

A

• If given before ageing has occurred, drugs like pralidoxime split the phosphorous-enzyme bond.

• Pralidoxime can be used as cholinesterase regenerator for organophosphate
insecticide poisoning.

PCM Exam 2 Pharm (14 decks)

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