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General - Pharmacology 💊 > L4: Cholinergic Pharmacology > Flashcards

L4: Cholinergic Pharmacology Flashcards

1
Q

What are parasympathomimetics classified according to tp?

A

According to MOA:

Direct-acting cholinomimetics
Indirect-acting cholinomimetics

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2
Q

What is the definition of Direct-acting cholinomimetics?

A

Act by direct stimulation of cholinergic receptors.

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3
Q

What are examples of Direct-acting cholinomimetics?

A

A-choline esters:
acetylcholine, (M+N)
Bethanechol (M)
Carbachol (M+N)

B-alkaloids :
Natural :Pilocarpine(M)
Synthetic: Cevimeline (M)

C-drugs that augment A.ch.action:
sildenafil

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4
Q

What is the definition of Indirect-acting cholinomimetics?

A

Act by inhibition of choline esterase (AChE) enzyme leading to accumulation of acetylcholine (A.Ch).

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5
Q

What are examples of Indirect-acting cholinomimetics?

A

Reversible Ch.E inhibitors.:
> Physostigmine (M+N +CNS; used topically in glaucoma),
> neostigmine,
> pyridostigmine, donepezil

Irreversible Ch.E inhibitors;

a) Echothiopate: eye drops to treat
b) Organophosphate compounds (M+N +CNS effects)

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6
Q

What are the adverse effects of muscarinic agonists?

A

DUMBELS

D 
> Diarrhea &colic
U
> Urination
M
> Miosis
B
> Bradycardia & Bronchospasm
E
> Emesis(Vomiting) & Excretion of CNS
L
> Lacrimation
S
> Salivation, Sweating & Skeletal ms twitches

-All of which can be blocked by atropine.

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7
Q

What are the contradictions of muscarinic agonists?

A

Peptic ulcer.
Bronchial asthma.
Heart Block.

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8
Q

What is the nature of physostigmine?

A

Natural plant alkaloid (tertiary amine).
Well-absorbed from the GIT
Can pass to CNS.

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9
Q

What is the MOA of physostigmine?

A

(Reversibly) inhibit cholinesterase enzyme for 3-4 hours,
leading to :
1. Muscarinic effects:
> Hypotension, Bradycardia.
> Salivation, lacrimation.
> +1 GIT peristalsis (diarrhea and colic).
> Miosis.

  1. Nicotinic effects:
    > Skeletal muscle contraction.
  2. Central effects:
    > Headache, insomnia, excitation, and convulsions.
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10
Q

What are the uses of physostigmine?

A
  • Eye drops to produce miosis and treat chronic glaucoma.

- The antidote in case of atropine poisoning.

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11
Q

What is the nature of neostigmine?

A 
Synthetic drug (quaternary amine)
Poorly absorbed from GIT.
Cannot pass to CNS.
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12
Q

What is the MOA of Neostigmine?

A

Similar to physostigmine in MOA & effects but it has no CNS actions.

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13
Q

What are the uses of neostigmine?

A
  • Reverse postoperative urine retention and paralytic ileus.
  • Contraindicated if it is mechanical obstruction (to avoid rupture of the bladder or intestine)
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14
Q

What is the MOA of edrophonium?

A

Similar to pyridostigmine & neostigmine but has a very short duration of action (5-15 minutes).

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15
Q

What are the uses of edrophonium?

A

It is used in the diagnosis of myathenia gravis, Used to differentiate between muscle weakness due to insufficient treatment of myasthenia, or due to excessive treatment with cholinesterase (Tensilon test).

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16
Q

Drugs for a Patient with glaucoma

A

Ecothiophate (Parasympathomimetic)

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17
Q

Drugs for the Diagnosis of myasthenia

A

Edrophonium

18
Q

Drugs for the Treatment of myasthenia

A

Neo and pyridostigmine

19
Q

What are organophosphate compounds?

A

-Drugs:
Echothiophate eye drops.

-Insecticides:
Parathion.
Malathion.

Nerve (war) gases:
Sarin
Soman

20
Q

What are the manifestations of organophosphate compounds toxicity?

A

(The DUMBELS syndrome) (Excretion, Bradycardia, Bronchospasm)

D 
> Diarrhea &colic
U
> Urination
M
> Miosis
B
> Bradycardia & Bronchospasm
E
> Emesis(Vomiting) & Excretion of CNS
L
> Lacrimation
S
> Salivation, Sweating & Skeletal ms twitches
21
Q

What is the management of organophosphate toxicity?

A
  • Ensure patent airway and artificial respiration.
  • Gastric lavage and skin wash to remove the toxin.
  • Intravenous normal saline to raise blood pressure.

Atropine - Pralidoxime - diazepam

22
Q

What are the drugs used for Postoperative urine retention and paralytic ileus and their receptors?

A
  • Bethanechol, M3

- Neostigmine, M&N

23
Q

What are the drugs used for glaucoma?

A
  • Pilocarpine, M3

* Carbachol, physostigmine, M&N

24
Q

What are the drugs used for xerostomia?

A

Cevimeline, M3

25
Q

What are the drugs used for Alzheimer’s disease?

A

Donepezil, rivastigmine, M&N

26
Q

What are the drugs used for the diagnosis of myasthenia?

A

Edrophonium

27
Q

What are the drugs used for the Treatment of Myasthenia?

A

Edrophonium,

28
Q

What are the drugs used for the treatment of Atropine toxicity?

A

Physostigmine, M&N

29
Q

Bethanechol clinical application and action

A
  • Postoperative urine retention and paralytic ileum

- Activates bowel and bladder smooth ms.

30
Q

Pilocarpine clinical application and action

A
  • Glaucoma

- Activates ciliary muscle of eye

31
Q

Neostigmine clinical application and action

A
  • Postoperative urine retention, Myasthenia gravis, and paralytic ileus
  • Amplifies endogenous acetylcholine
32
Q

Physostigmine clinical application and action

A
  • Glaucoma, counteract the mydriatic cycloplegic of atropine

- Amplifies endogenous acetylcholine

33
Q

What are examples of parasympatholytics?

A

1- Nicotinic blockers:

-NMBs (block Nm)
> e.g: D- tubocurarine.
-Ganglionic blockers (block Nn):
> e.g: Trimethaphan.

2- Muscarinic antagonists:

-Ipratropium
Hyoscine butylbromide
-Pirenzepine (M1)
-Oxybutynin, tolterodine
-hamatropine, tropicamide
-Benztropine
34
Q

What is the nature of muscarinic antagonists?

A

They are either tertiary amine alkaloids or quaternary amines :

> Plant alkaloids: atropine & scopolamine (hyoscine) is found in Hyoscyamus
Niger. They are tertiary amines (i.e. well absorbed and can pass to CNS).

> Synthetic derivatives: either tertiary or quaternary amines (limited CNS penetration).

35
Q

What is the action of different muscarinic antagonists?

A

Ipratropium: Used mainly as bronchodilators.

Hyoscine butyl bromide: Used mainly as antispasmodics.

Pirenzepine (M1): Used mainly to decrease HCL secretion.

Oxybutynin, tolterodine: Used mainly for the genitourinary system.

Homatropine, tropicamide: Used mainly as mydriatics.

Benztropine: Used mainly to treat parkinsonism.

36
Q

What are the therapeutic uses of muscarinic antagonists?

A
  • Bradycardia (atropine, mainly M2).
  • Bronchial asthma: (ipratropium is given by inhalation to dilate the bronchi and reduce secretions in asthma and chronic obstructive pulmonary disease (COPD).

• Pre-anesthetic medication (atropine GIT disorders) :
> Peptic ulcer: pirenzepine. (M 1- antagonist).
> Diarrhea.
> Abdominal colic: eg , hyoscine butylbromide (Buscoban)

• Urinary disorder :
> Acute cystitis: oxybutynin
> Urine incontinence in adults: tolterodine

  • Eye: Funds examination &lridocyclitis
  • CNS: Parkinson’s disease: benztropine
  • Motion sickness: scopolamine.
  • Organophosphate toxicity: atropine.
37
Q

What is the nature of atropine?

A

An alkaloid derived from the plant Atropa belladonna.

38
Q

What is the MOA of atropine?

A

Competes reversibly with Ach at the muscarinic receptors both peripherally and centrally.

39
Q

What are the pharmacological effects of atropine? Ml DDT

A

• Mydriasis, cycloplegia & loss of accommodation to near
vision
• Tachycardia (increased heart rate).
• Decreases the tone and motility of GIT & UB
• Decrease the secretions (salivary, lacrimal).
• large doses - skin flushing, hallucinations & coma.

40
Q

What are the therapeutic uses of atropine?

A
  1. Antispasmodic
  2. Bradycardia
  3. Pre-anesthetic agent
  4. Funds examination.
  5. Treatment of poisoning by anticholinesterase agents
    because it antagonizes the actions of Ach (OCP
    poisoning)
41
Q

What are the side effects of atropine?

A
  1. Rapid pulse.
  2. Dilated pupils, resulting in photophobia &blurred vision.
  3. Dry mouth.
  4. Flushed skin.
  5. Rise in body temperature, especially in children.
  6. Restlessness, confusion, and disorientation.

General - Pharmacology 💊 (9 decks)

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