L4: Cholinergic Pharmacology Flashcards by Ahmed Farag

What are parasympathomimetics classified according to tp?

According to MOA:

Direct-acting cholinomimetics
Indirect-acting cholinomimetics

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What is the definition of Direct-acting cholinomimetics?

Act by direct stimulation of cholinergic receptors.

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What are examples of Direct-acting cholinomimetics?

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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What is the definition of Indirect-acting cholinomimetics?

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

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What are examples of Indirect-acting cholinomimetics?

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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What are the adverse effects of muscarinic agonists?

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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What are the contradictions of muscarinic agonists?

Peptic ulcer.
Bronchial asthma.
Heart Block.

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What is the nature of physostigmine?

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

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What is the MOA of physostigmine?

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

Nicotinic effects:
> Skeletal muscle contraction.
Central effects:
> Headache, insomnia, excitation, and convulsions.

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What are the uses of physostigmine?

Eye drops to produce miosis and treat chronic glaucoma.

- The antidote in case of atropine poisoning.

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What is the nature of neostigmine?

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

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What is the MOA of Neostigmine?

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

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What are the uses of neostigmine?

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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What is the MOA of edrophonium?

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

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What are the uses of edrophonium?

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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Drugs for a Patient with glaucoma

Ecothiophate (Parasympathomimetic)

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Drugs for the Diagnosis of myasthenia

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Edrophonium

Drugs for the Treatment of myasthenia

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Neo and pyridostigmine

What are organophosphate compounds?

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-Drugs:
Echothiophate eye drops.

-Insecticides:
Parathion.
Malathion.

Nerve (war) gases:
Sarin
Soman

What are the manifestations of organophosphate compounds toxicity?

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(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

What is the management of organophosphate toxicity?

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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

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

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Bethanechol, M3

- Neostigmine, M&N

What are the drugs used for glaucoma?

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Pilocarpine, M3

* Carbachol, physostigmine, M&N

What are the drugs used for xerostomia?

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Cevimeline, M3

What are the drugs used for Alzheimer's disease?

Donepezil, rivastigmine, M&N

What are the drugs used for the diagnosis of myasthenia?

Edrophonium

What are the drugs used for the Treatment of Myasthenia?

Edrophonium,

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

Physostigmine, M&N

Bethanechol clinical application and action

- Postoperative urine retention and paralytic ileum | - Activates bowel and bladder smooth ms.

Pilocarpine clinical application and action

- Glaucoma | - Activates ciliary muscle of eye

Neostigmine clinical application and action

- Postoperative urine retention, Myasthenia gravis, and paralytic ileus - Amplifies endogenous acetylcholine

Physostigmine clinical application and action

- Glaucoma, counteract the mydriatic cycloplegic of atropine | - Amplifies endogenous acetylcholine

What are examples of parasympatholytics?

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 ```

What is the nature of muscarinic antagonists?

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).

What is the action of different muscarinic antagonists?

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.

What are the therapeutic uses of muscarinic antagonists?

* 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.

What is the nature of atropine?

An alkaloid derived from the plant Atropa belladonna.

What is the MOA of atropine?

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

What are the pharmacological effects of atropine? Ml DDT

• 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.

What are the therapeutic uses of atropine?

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)

What are the side effects of atropine?

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.

L4: Cholinergic Pharmacology Flashcards

(41 cards)