Parasympathetics

Question 1

Bethanechol

Answer 1

Action:
Direct agonist
Activates bowel and bladder smooth muscle
Resistant to AChE

Use:
Postoperative ileus, neurogenic ileus, urinary retention

Question 2

Carbachol

Answer 2

Action:
Direct agonist
Constricts pupil and relieves intraocular pressure in open angle glaucoma
Stimulates both muscarinic and nicotinic receptors

“carbon copy of acetylcholine”

Question 3

Methacholine

Answer 3

Action:
Direct agonist
Stimulates muscarinic receptors in airway when inhaled

Use:
Challenge test for diagnosis of asthma

Question 4

Pilocarpine

Answer 4

Action:
Direct agonist
Contracts ciliary muscle of eye (open angle glaucoma)
Contracts pupillary sphincter (closed angle glaucoma)

Use:
Potent stimulator of sweat, tears and saliva
Open angle / closed angle glaucoma
Xerostomia (Sjogren syndrome)

Question 5

Donepezil, Galantamine, Rivastigmine

Answer 5

Action:
Anticholinesterase
Increase ACh

Use:
Alzheimer disease

Question 6

Edrophonium

Answer 6

Action:
Anticholinesterase
Increase ACh

Use:
Diagnosis of myasthenia gravis (extremely short acting)

Question 7

Neostigmine

Answer 7

Action:
Anticholinesterase
Increase ACh
No CNS penetration (quaternary amine)

Use:
Postoperative and neurogenic ileus and urinary retention
Myasthenia gravis
Reversal of nondepolarizing neuromuscular junction blockage

Question 8

Physostigmine

Answer 8

Action:
Anticholinesterase
Increase ACh

Use:
Anticholinergic toxicity (atropine overdose)
Crosses BBB –> CNS (tertiary amine)

Question 9

All cholinomimetics can exacerbate what?

Answer 9

COPD, asthma, and peptic ulcers when giving to susceptible patients

Question 10

Cholinesterase inhibitor poisoning

Answer 10

Diarrhea
Urination
Miosis
Bronchospasm
Bradycardia
Excitation of skeletal muscle and CNS
Lacrimation
Sweating
Salivating

Due to organophosphates (parathion, insecticides) that irreversibly inhibit AChE.
May lead to respiratory failure if untreated.
Antidote - atropine (competitive inhibitor) + pralidoxime (regenerates AChE if given early)

Question 11

Atropine, Homatropine, Tropicamide

Answer 11

Muscarinic antagonist

Eye

Produce Mydriasis and cycloplegia

Question 12

Benztropine

Answer 12

Muscarinic antagonist

CNS

Parkinson disease

Acute dystonia

“park my benz”

Question 13

Glycopyrrolate

Answer 13

Muscarinic antagonist

GI, respiratory

Parenteral: preoperative use to reduce airway secretions
Oral: drooling, peptic ulcer

Question 14

Hyoscyamine, Dicyclomine

Answer 14

Muscarinic antagonist

GI

Antispasmodics for irritable bowel syndrome

Question 15

Ipratropium, Tiotropium

Answer 15

Muscarinic antagonist

Respiratory

COPD, Asthma

tiotropium is longer acting

“I pray I can breathe soon”

Question 16

Oxybutynin, Solifenacin, Tolterodine

Answer 16

Muscarinic antagonist

Genitourinary

Reduce bladder spasms and urge urinary incontinence (overactive bladder).

Question 17

Scopolamine

Answer 17

Muscarinic antagonist

CNS

Motion sickness

Question 18

Atropine

Answer 18

Used to treat bradycardia and ophthalmic applications

Blocks DUMBBeLSS - inc. pupil dilation, cycloplegia, dec. secretions in airway, dec. acid secretion in stomach, dec. gut motility, dec. bladder urgency in cystitis.

Does not block excitation of skeletal muscle and CNS (mediated by nicotinic receptors)

Adv. effects: 
Hot as a hare (increase in body temp)
Dry as a bone (dry mouth)
Red as a beet (flushed skin)
Blind as a bat (cycloplegia)
Mad as a hatter (disorientation)

acute angle closure glaucoma in elderly (due to mydriasis)
urinary retention in men with prostatic hyperplasia
hyperthermia in infants

Jimson weed –> gardener’s pupil (mydriasis due to plant alkaloids)