Chapter 14 - Muscarinic Agonists & Antagonists

Question 1

Muscarinic Agonist - def

Answer 1

drugs that bind to muscarinic receptors and cause receptor activation.

Question 2

Muscarinic Agonist drugs are associated with….

Answer 2

parasympathetic system, and their effects mimic those produced by parasympathetic stimulation.

Question 3

Muscarinic Agonists cause….

Answer 3

bradycardia, increased sweating, increased secretion of gastric acid, contraction of smooth muscle, contraction of bladder, etc.

Question 4

Muscarinic Agonist (Prototype)

Answer 4

Bethanechol.

Question 5

Bethanecol - pharmacologic effects.

Answer 5

Reversible binding to muscarinic cholinergic receptors and causes activation.

Question 6

Therapeutic uses to treat - Bethanecol

Answer 6

Urinary retention - post operative patients.
GERD - increase oesophageal motility.
Ileus - increases motility/tone.
Post-operative abdominal distention - increases movement.

Question 7

Bethanecol - Pharmacokinetics - Administration

Answer 7

Orally - effects begin 30-60 minutes and last 1 hour. Dose must be much larger than SC.

Subcutaneous - Effects in 5-15 minutes and last 1 hour. BUT THIS HAS BEEN REMOVED FROM MARKET.

Question 8

Bethanecol - not toxic if injected IM or IV. T/F?

Answer 8

FALSE. it is!

Question 9

Adverse Effects - Bethanecol - __ with oral, ___ with SC.

What are some?

Answer 9

Rare/High.

hypotension, abdominal cramps & diarrhea, causes bronchiolar constriction, dysrhythmias.

Question 10

Other Muscarinic Agonist Agents - 3 and uses.

Answer 10

Pilocarbin (Glaucoma), Acetylcholine (clinically used for constriction of pupil during surgery.
Muscarine - mushrooms - not used clinically.

Question 11

Muscarinic Agonist Poisoning - 3

Answer 11

Ingestion of mushrooms, Overdose of Direct Acting Muscarinic Agonists, Overdose of Cholinesterase Inhibitors

Question 12

Muscarinic Poisoning Symptoms -

Answer 12

profuse salivation, lacrimation, visual disturbance, etc.

Question 13

Treatment for Muscarinic Agonist Poisoning -

Answer 13

Muscarinic Blocking Agent - Atropine

Question 14

Muscarinic Antagonist - def

Answer 14

drug that blocks the action of acetylcholine at muscarinic receptors.

Question 15

Prototype Drug - Muscarinic Antagonist -

Answer 15

Atropine.

Question 16

Where does atropine come from?

Answer 16

Variety of plants, like Atropa Belladonna (deadly nightshade) and Datura Stramonium (jimsonweed, stinkweed, devil’s apple.)

Question 17

Atropine - pharmacokinetics

Answer 17

Administered orally, topically, and by injection (IM, IV, SC), goes to all tissues (including CNS), Elimination by urinary mechanisms and liver, 1/2 life about 3 hours.

Question 18

Atropine - Therapeutic Uses -

Answer 18

Eye exam and surgery, bradycardia, biliary colic - intense abdominal pain, increased gastric motility, etc.

Question 19

Atropine Adverse effects -

Answer 19

Dry mouth (xerostomia), Blurred vision, photophobia, increased intraocular pressure, etc.

Question 20

Anti-Muscarinic Poisoning - Sources

Answer 20

Like the atropa belladonna and datura stramonium, atropin, scopolamine, anti-histamines, etc.

Question 21

Symptoms of Anti-Muscarinic Poisoning -

Answer 21

dry mouth, blurred vision, photophobia, hyperthermia, CNs effects, hot/dry skin.

Question 22

Treatment for Anti-muscarinic poisoning -

Answer 22

avoid anti-histamines, phenothiazine antipsychotic and tricyclic antidepressants…

Question 23

Other muscarinic antagonist agents (4.)

Answer 23

Scopolamine - sedation and suppression of emesis and motion sickness.
Ipratropium - treat asthma and allergies.
Tolterodine - used for incontinence treatment.
Dicyclomine - used for IBS.