Cholinergic and Anti-Cholinergic Drugs

Question 1

called parasympathomimetic or cholinomimetic

?

Answer 1

Cholinergic Drugs

Question 2

Similar in action as acetylcholine?

Answer 2

Cholinergic Drugs

Question 3

We don’t use acetylcholine itself, because ?

Answer 3

it acts on both muscarinic and nicotinic (not selective) and has short duration of action (rapidly metabolized by acetycholinesterase)

Question 4

Cholinergic Drugs Stimulate cholinergic receptors directly or indirectly by

Answer 4

decreasing
 acetylcholine metabolism (by inhibiting acetylcholinesterase enzyme)

Question 5

1- Direct acting Cholinergic Drugs ● Examples?

Answer 5

● Acetylcholine ● Carbachol ● Bethanechol ● Pilocarpine

Question 6

Pharmacological properties of Direct acting Cholinergic Drugs

Answer 6

● Poorly distributed and can not cross BBB (No CNS effects)
● Not metabolized by cholinesterase (except Acetylcholine)
● Have longer duration of action than Acetylcholine.

Question 7

Direct acting Cholinergic Drugs

- Pharmacological effects ?

Answer 7

●  Increased contractility in gastrointesinal smooth muscle wall, with relaxation
of sphincters (diarrhea) 

● Increased contractility of smooth muscle wall in urinary bladder, with
relaxation of sphincter (urinary incontinence)

●  Increased contractility of bronchial smooth muscle, with increased
respiratory secretions (induce asthma) 

● Constriction of pupils (miosis) and contraction of ciliary muscle (treatment of
glucoma)

Question 8

Acetylcholine

Receptor? Metabolism by cholinesterase? Selectivity ? Uses?

Answer 8

• Muscarinic / Nicotinic
• Metabolized
• Not selective
• NOT used

Question 9

Carbachol

Receptor? Metabolism by cholinesterase? Selectivity ? Uses?

Answer 9

• Muscarinic / Nicotinic
• NOT metabolized by cholinesterase
• Eye / Gastrointestinal / Urinary bladder
• Glaucoma

Question 10

Bethanechol

Receptor? Metabolism by cholinesterase? Selectivity ? Uses?

Answer 10

• Muscarinic
• NOT metabolized by cholinesterase
• Gastrointestinal / Urinary bladder
• Paralytic ileus / Urinary retention

Question 11

Pilocarpine

Receptor? Metabolism by cholinesterase? Selectivity ? Uses?

Answer 11

• Muscarinic
• NOT metabolized by cholinesterase
• Eye / Exocrine glands
• Glaucoma / Xerostomia

Question 12

Direct acting Cholinergic Drugs

Contraindications?

Answer 12

● Bronchial asthma
● Peptic ulcer
● Angina pectoris
● Urinary incontinence
● Intestinal obstruction

Question 13

Also called anticholinesterases ?

Answer 13

Indirect acting Cholinergic Drugs

Question 14

Indirect acting Cholinergic Drugs

Mechanism of action ?

Answer 14

● Prevent hydrolysis of acetylcholine by inhibiting acetylcholinesterase enzyme
● Thus increase acetylcholine concentrations and actions at the cholinergic receptors (both nicotinic and muscarinic)

Question 15

Indirect acting Cholinergic Drugs Classification ?

Answer 15

Reversible anticholinesterases: 
●  Short acting:    
- Edrophonium (diagnosis of myasthenia gravis)
 - Donepezil (treatment of Alzheimer's disease) 
●  Intermediate acting: 
-Neostigmine
-Physostigmine
-Pyridostigmine

Irreversible anticholinesterases
● Long acting as Ecothiophate = Phosphates used as insecticides and gas war

Question 16

Indirect acting Cholinergic Drugs Pharmacological actions?

Answer 16

Nicotinic actions:

1. Neuromuscular junction:
   At therapeutic dose cause skeletal muscle contraction At toxic dose cause relaxation and paralysis
2. Ganglia: stimulation of both sympathetic and parasympathetic ganglia
3. Adrenal medulla: induce release of catecholamines (adrenaline &
   noradrenaline).

Question 17

Indirect acting Cholinergic Drugs Pharmacological actions: Muscarinic actions

Answer 17

1. Eye: Contraction of circular muscle of iris (miosis) / Contraction of ciliary muscles for near vision /Decrease in intraocular pressure
2. Cardio vascular : Bradycardia with vasodilatation
3. Lung : Constriction of bronchial smooth muscles/ Increase bronchial secretion
4. GIT : Increased motility (peristalsis) & relaxation of sphincter
   Increased secretion
5. Urinary bladder : Contraction of muscles & relaxation of sphincter
6. Exocrine glands : Increase of sweat, saliva, lacrimal, bronchial, intestinal secretions

Question 18

Indirect acting Cholinergic Drugs

Actions on?

Answer 18

Both Nicotinic & muscarinic

Question 19

Diagnosis of myasthenia
gravis (Tensilon test)
Drug used ?

Answer 19

Edrophonium

Question 20

Treatment of Alzheimer’s disease

Drug used?

Answer 20

Donepezil

Question 21

Myasthenia gravis treatment
Paralytic ileus
Urinary retention

Used?

Answer 21

Neostigmine

Question 22

Myasthenia gravis treatment

Drug used?

Answer 22

Pyridostigmine

Question 23

Glaucoma
Atropine toxicity
Drug used?

Answer 23

Physostigmine

Question 24

Glaucoma ?

Answer 24

Ecothiophate

Question 25

Organophosphates toxicity ?

Answer 25

Toxicity of irreversible anticholinesterases (cholinergic crisis)

Question 26

Symptoms of Organophosphates toxicity ?

Answer 26

● Muscarinic: salivation, lacrimation, urination, diarrhea, emesis,
bronchospasm, bradycardia, miosis

● Nicotinic: muscle fasciculation and weakness.

Question 27

Organophosphates toxicity Treatment ?

Answer 27

● Decontamination of clothing
● Flushing poison from skin and eyes
● Activated charcoal and gastric lavage for gastrointestinal ingestion
● Atropine for muscarinic effects
● Pralidoxime (cholinesterase reactivator) causes breaking the bond
between the enzyme and poison, so given as soon as possible because if too much time passes, the poison bond becomes too strong

Question 28

Also called cholinergic blocking drugs or parasympatholytics ?

Answer 28

Anticholinergics

Question 29

Muscarinic antagonists ?

Answer 29

● Natural:
- Atropine 
- Hyoscine
● Synthetic: 
- Benztropine 
- Homatropine 
- Ipratropium

Question 30

Treatment of overdose of anti-muscarinic drugs?

Answer 30

Antidote: Physostigmine

Question 31

Pre-anesthetic medication
Antispasmodic

Drug?

Answer 31

Atropine

Question 32

Pre-anesthetic medication Antispasmodic
Antiemetic in motion sickness

Drug?

Answer 32

Hyoscine

Question 33

Parkinson’s disease

Drug?

Answer 33

Benztropine

Question 34

Fundus examination of eye

Drug used?

Answer 34

Homatropine

Question 35

Asthma

Drug used?

Answer 35

Ipratropium

Question 36

Side effects of anti-muscarinic drugs

?

Answer 36

● Eye: blurred vision due to mydriasis
● Tachycardia
● Urinary retention
● Constipation, paralytic ileus
● Dryness of mouth, sandy eye, hyperthermia
● CNS: hallucination, excitation (Toxic dose).