Pharm - cholinoreceptors

Question 0

Antagonist effects on body

Answer 0

Cardiovascular system
Little effect on BP (why?)
↑ HR
Gastrointestinal tract
↓Salivary secretions
↓Gastric secretions (very high doses only), tone and motility (stomach to colon)
(Indicated or contraindicated for ulcers?)
Spasmolytic
Bronchioles
↓Secretions
Bronchodilatation (Indicated or contraindicated for asthma?)
Eyes
– Iris (dilatation) - mydriasis, photophobia
Ciliary muscle - cycloplegia: paralysis of accommodation (lens fixed for distant
vision, near objects appear blurred)
↑Intraocular pressure (Indicated or contraindicated in the presence of glaucoma?)Urinary tract (relaxation)
Sweat glands - anhydrosis - large dose may cause hyperpyrexia
CNS
– Therapeutic doses - minimal effects
Toxic doses - mania and excitement, followed by depression and coma
Opthalmic uses:
–  To facilitate ophthalmoscopic examination (tropicamide preferred because of its very short duration of action)

Question 1

Agonist effects on body

Answer 1

• bronchoconstrictive effect
• administered only by inhalation
• serious side effects including GI symptoms, chest pain, hypotension, loss of consciousness, and complete heart block have occurred when the drug is given orally or parenterally
  -Eye: miosis, constrict ciliary muscle, decrease intraocular pressure (good for glaucoma)
  -GI: contractions enhanced, gastric acid secretions increased
  -neuromuscular junction: antagonizes neuromuscular blockade
  -Secretory glands: activity increased
  (bronchial, lacrimal, gastric, intestinal, pancreatic, sweat)

Question 2

Methacholine

Answer 2

-Agonist (muscarinic)
-is a choline ester
Effects on body:
- bronchoconstrictive effect
- administered only by inhalation
- serious side effects including GI symptoms, chest pain, hypotension, loss of consciousness, and complete heart block have occurred when the drug is given orally or parenterally
-Eye: miosis, constrict ciliary muscle, decrease intraocular pressure (good for glaucoma)
-GI: contractions enhanced, gastric acid secretions increased
-neuromuscular junction: antagonizes neuromuscular blockade
-Secretory glands: activity increased
(bronchial, lacrimal, gastric, intestinal, pancreatic, sweat)

Question 3

Bethanacol

Answer 3

-Agonist (muscarinic)
-is a choline ester (is a carbamate derivative of methacholine)
Effects on body:
-Eye: miosis, constrict ciliary muscle, decrease intraocular pressure (good for glaucoma)
-GI: contractions enhanced, gastric acid secretions increased
-neuromuscular junction: antagonizes neuromuscular blockade
-Secretory glands: activity increased
(bronchial, lacrimal, gastric, intestinal, pancreatic, sweat)
** is occasionally used postoperatively to reinstitute peristaltic activity in the gut or to force the extrusion of urine from an atonic bladder. It is administered SQ or orally to avoid effects in other organ systems.

Question 4

Edrophonium

Answer 4

-agonist (is a cholinomimetic)
-binds to acetylcholinesterase or pseudocholinesterase
- inhibits metabolism of ACh
- Only binds to anionic site
- Rapidly reversible (seconds - minutes)
Effects on body:
-Eye: miosis, constrict ciliary muscle, decrease intraocular pressure (good for glaucoma)
-GI: contractions enhanced, gastric acid secretions increased
-neuromuscular junction: antagonizes neuromuscular blockade
-Secretory glands: activity increased
(bronchial, lacrimal, gastric, intestinal, pancreatic, sweat)

Question 5

Physostigmine

Answer 5

• agonist (a cholinomimetic)
• binds acetylcholinesterase or pseudocholinesterase
• Slowly reversible
• Form more stable carbamyl linkage
  Effects on body:
  -Eye: miosis, constrict ciliary muscle, decrease intraocular pressure (good for glaucoma)
  -GI: contractions enhanced, gastric acid secretions increased
  -neuromuscular junction: antagonizes neuromuscular blockade
  -Secretory glands: activity increased
  (bronchial, lacrimal, gastric, intestinal, pancreatic, sweat)

Question 6

neostigmine

Answer 6

• agonist (a cholinomimetic)
• binds acetylcholinesterase or pseudocholinesterase
• Slowly reversible
• Form more stable carbamyl linkage
  Effects on body:
• Myasthenia Gravis (KNOW)
  -Eye: miosis, constrict ciliary muscle, decrease intraocular pressure (good for glaucoma)
  -GI: contractions enhanced, gastric acid secretions increased
  -neuromuscular junction: antagonizes neuromuscular blockade
  -Secretory glands: activity increased
  (bronchial, lacrimal, gastric, intestinal, pancreatic, sweat)

Question 7

parathion

Answer 7

• agonist
• organophosphate
• irreversible
  Example:
• Insecticides
  Effects on body:
  -Eye: miosis, constrict ciliary muscle, decrease intraocular pressure (good for glaucoma)
  -GI: contractions enhanced, gastric acid secretions increased
  -neuromuscular junction: antagonizes neuromuscular blockade
  -Secretory glands: activity increased
  (bronchial, lacrimal, gastric, intestinal, pancreatic, sweat)

Question 8

nerve gases

Answer 8

-agonist (blocks ACh esterase)
-organophosphate
-irreversible
-very stable linkage with enzyme
Effects on body:
- contraction of pupils, profuse salivation, convulsions, involuntary urination and defecation, and eventual death by asphyxiation as control is lost over respiratory muscles.

Question 9

pralidoxime

Answer 9

-antagonist
-cholinesterase reactivator
Effects on body:
Cardiovascular system
Little effect on BP (why?)
↑ HR
Gastrointestinal tract
↓Salivary secretions
↓Gastric secretions (very high doses only), tone and motility (stomach to colon)
(Indicated or contraindicated for ulcers?)
Spasmolytic
Bronchioles
↓Secretions
Bronchodilatation (Indicated or contraindicated for asthma?)
Eyes
– Iris (dilatation) - mydriasis, photophobia
Ciliary muscle - cycloplegia: paralysis of accommodation (lens fixed for distant
vision, near objects appear blurred)
↑Intraocular pressure (Indicated or contraindicated in the presence of glaucoma?)Urinary tract (relaxation)
Sweat glands - anhydrosis - large dose may cause hyperpyrexia
CNS
– Therapeutic doses - minimal effects
Toxic doses - mania and excitement, followed by depression and coma

Question 10

atropine

Answer 10

-antagonist
Effects on body:
-reverses peripheral muscarinic and central effects but has no effect on neuromuscular junction (paralysis)
Cardiovascular system
Little effect on BP (why?)
↑ HR
Gastrointestinal tract
↓Salivary secretions
↓Gastric secretions (very high doses only), tone and motility (stomach to colon)
(Indicated or contraindicated for ulcers?)
Spasmolytic
Bronchioles
↓Secretions
Bronchodilatation (Indicated or contraindicated for asthma?)
Eyes
– Iris (dilatation) - mydriasis, photophobia
Ciliary muscle - cycloplegia: paralysis of accommodation (lens fixed for distant
vision, near objects appear blurred)
↑Intraocular pressure (Indicated or contraindicated in the presence of glaucoma?)Urinary tract (relaxation)
Sweat glands - anhydrosis - large dose may cause hyperpyrexia
CNS
– Therapeutic doses - minimal effects
Toxic doses - mania and excitement, followed by depression and coma

Question 11

scopalomine

Answer 11

-antagonist
Effects on body:
Cardiovascular system
Little effect on BP (why?)
↑ HR
Gastrointestinal tract
↓Salivary secretions
↓Gastric secretions (very high doses only), tone and motility (stomach to colon)
(Indicated or contraindicated for ulcers?)
Spasmolytic
Bronchioles
↓Secretions
Bronchodilatation (Indicated or contraindicated for asthma?)
Eyes
– Iris (dilatation) - mydriasis, photophobia
Ciliary muscle - cycloplegia: paralysis of accommodation (lens fixed for distant
vision, near objects appear blurred)
↑Intraocular pressure (Indicated or contraindicated in the presence of glaucoma?)Urinary tract (relaxation)
Sweat glands - anhydrosis - large dose may cause hyperpyrexia
CNS
– Therapeutic doses - minimal effects
Toxic doses - mania and excitement, followed by depression and coma

Question 12

tropicamide

Answer 12

-antagonist
-short-acting version of atropine
Effects on body:
Cardiovascular system
Little effect on BP (why?)
↑ HR
Gastrointestinal tract
↓Salivary secretions
↓Gastric secretions (very high doses only), tone and motility (stomach to colon)
(Indicated or contraindicated for ulcers?)
Spasmolytic
Bronchioles
↓Secretions
Bronchodilatation (Indicated or contraindicated for asthma?)
Eyes
– Iris (dilatation) - mydriasis, photophobia
Ciliary muscle - cycloplegia: paralysis of accommodation (lens fixed for distant
vision, near objects appear blurred)
↑Intraocular pressure (Indicated or contraindicated in the presence of glaucoma?)Urinary tract (relaxation)
Sweat glands - anhydrosis - large dose may cause hyperpyrexia
CNS
– Therapeutic doses - minimal effects
Toxic doses - mania and excitement, followed by depression and coma
Opthalmic uses:
–  To facilitate ophthalmoscopic examination (tropicamide preferred because of its very short duration of action)

Question 13

ipratropium

Answer 13

-antagonist (muscarinic receptor blocker)
Effects on body/uses:
-usual antagonistic effects
-(Atrovent) is a quaternary (charged at all pHs) derivative ofatropine
-Inhaled into lungs
-Most effective for nocturnal asthma
-Suggests that increased vagal tone during sleep may play an active role

Question 14

Trihexyphenidyl

Answer 14

-antagonist (muscarinic receptor blocker)
Effects on body/uses:
- antagonistic effects
- Parkinson’s disease
(drug of choice is levodopa although centrally acting anticholinergics may also be used such as this one)

Question 15

Trimethaphan

Answer 15

-antagonist (ganglionic blocker)
Effects on body/uses:
- same as all antagonists
-“drug of last resort”
- clinical use limited to acute management of hypertensive emergencies
- because of the number of systems adversely affected by these drugs, they are not used as first line therapy