Direct-acting ACh receptor agoists 1 (choline esters)

Question 1

Direct-acting ACh receptor agonists (3 groups)

Answer 1

Choline esters
Plant alkaloids
Synthetic drugs

Question 2

Choline esters (3 drugs)

Answer 2

Acetylcholine
Bethanechol (synthetic ACh analogue)
Carbachol (synthetic ACh analogue)

Question 3

Distribution of choline esters

Answer 3

Not distributed to CNS

Question 4

Receptors that the different choline esters activate

Answer 4

Acetylcholine + carbachol: both muscarinic and nicotinic receptors.
Bethanechol: Only muscarinic receptors

Question 5

Direct-acting ACh agonists - MOA

Answer 5

Bind to and activate ACh receptors

Question 6

Effects of muscarinic receptor activation (3 ocular, 2 respiratory, 1 vascular)

Answer 6

Lacrimal gland secretion.
Contraction of iris sphincter muscle (miosis).
Contraction of ciliary muscles (accomodation).
Bronchial muscle contraction.
Mucus secretion in resp tract.
Vascular vasodilation.

Question 7

Drugs that activate muscarinic receptors should be avoided in which patients and why?

Answer 7

Asthma and obstructive lung diseases because of risk of bronchoconstriction.
Cardiac arrhythmias - prolonged PR interval

Question 8

Effects of muscarinic receptor activation (2 cardiac, 3 GI, 2 urinary)

Answer 8

Decrease impulse formation in SA node.
Slow conduction through AV node (increased PR interval).
Salivary secretion.
Gastric acid secretion.
Increased GI motility.
Stimulate bladder detrusor muscle and relax internal bladder sphincter (micturition).

Question 9

High doses of muscarine agonist may cause:

Answer 9

Excessive salivation.
Diarrhea.
Intestinal cramps.
Urinary incontinence.

Question 10

Choline esters - are all hydrolyzed by cholinesterase?

Answer 10

Only acetylcholine, not bethanechol or carbachol

Question 11

Acetylcholine - indications

Answer 11

Cataract surgery to produce miosis.

Diagnostic coronary angiography (localized vasoconstriction in vasospastic angina pectoris).

Question 12

Acetylcholine - administation

Answer 12

Intraocular or intracoronary injection.

Not effective as topical ocular administration

Question 13

Bethanechol - indications

Answer 13

Nonobstructive neurogenic urinary retention postoperatively or postpartum

Question 14

Bethanechol - contraindications

Answer 14

IV administration: cause hypotension and bradycardia

Question 15

Carbachol - indications

Answer 15

Ophthalmic surgery to produce miosis

Question 16

Carbachol is not used in

Answer 16

Open-angle glaucoma