Chapter 13: Muscarinic Agonists and Cholinesterase Inhibitors

Question 1

Muscarinic agonist (cholinergic agonist)

Answer 1

Drugs that stimulate parasympathetic nervous system (PNS) and Mimic parasympathetic neurotransmitter acetylcholine

This allows acetylcholine to persist and attach to the receptor site**

Enhance the effects of acetylcholine, increasing the actions of the PNS

In medicine, the use of cholinergic agonists is limited BC of the propensity to cause adverse effects in any organ under the control of the PNS

Question 2

direct-acting mus agonist

Answer 2

Act on the receptor to activate a tissue response

Question 3

indirect-acting mus agonist

Answer 3

Inhibits the action of the enzyme cholinesterase -> decrease Ach breakdown, increase available Ach.
Called cholinesterase inhibitors or anti-cholinesterase drugs

Question 4

Nicotine (patch, gum)

Answer 4

bind to nicotine cholinergic receptors. Nicotine is a stimulating drug, reaches brain fast -increased HR, increased BP, alertness (dopamine release)

Use: smoking cessation

Question 5

Pilocarpine (eye)

Answer 5

Topical therapy of glaucoma
Decrease IOP by allowing excess flid drain from eye
cholingeric agonist

Question 6

Pilocarpine (saliva sub)

Answer 6

Treat xerostomia
cholinergic agonist

Question 7

Metoclopramide (reglan)

Answer 7

helps with N/V and getting gut moving post-op. side effect diarrhea

Increase gastric emptying

muscarinic agonist

Question 8

Bethanechol

Answer 8

Tx for non-obstructive urinary retention
muscarinic agonist

Question 9

Pyrisostigmine

Answer 9

Drug of choice for MG
Increase muscle strength in MG
cholinesterase inhibtor

Question 10

SE of cholinergic meds

Answer 10

Heart: Hypotension, bradycardia
Eyes: Blurred vision, meiosis (constriction)
Glands: Excessive salivation, sweating,
GU: increased urination
GI: increased gastric acid, nausea, vomiting, diarrhea, abdominal cramps
Lungs: Bronchoconstriction

Question 11

Safety/monitoring of cholinergic drugs

Answer 11

Monitor BP, P, teach client to arise slowly
Record fluid intake and output
Have pt report difficulty breathing, drooling, N/V, D excessive sweating
Don’t double dose
Medic alert bracelet BC of potential for myasthenic crisis
If OD, give Antidote: atropine

Question 12

Toxicity of mus agonist

Answer 12

Can Result From:
Direct Acting muscarinic agonists
Cholinesterase Inhibitors
Mushrooms
Poisoning*

If OD, give Antidote: atropine 1-2 mg IM every 30 min

Quick onset of s/sx: 30-60 min

S/sx: SLUDGE and killer Bs
Salivation
Lacrimation
Urination
Defecation
GI upset
Emesis
Bronchospasm, bradycardia, bronchorrhea

Also, hypotension, difficuilty in visual accodiation, shock

Question 13

Posioning by cholinesterase inhibitors (organophosphate poisoning)

Answer 13

Caused by insecticides
Increase Ach, ovestimulatin of Ach receptors, see cholinergic tox
Common, thru skin

Question 14

Myasthenic crisis

Answer 14

Pts who inadequately medicate
Extreme muscle weakness caused by insufficient acetylcholine at the NMJ
Left untreated, it can result in death from paralysis of the muscles of respiration
A cholinesterase inhibitor (neostigmine) is used to relieve the crisis

Question 15

Cholinergic crisis

Answer 15

OD with cholinesterase inhibitors
Also is characterized by extreme muscle weakness and extreme paralysis
Treatment atropine

Question 16

Differing between MC and CC

Answer 16

Similar symptoms

Treated very differently

Need med history, if you cant, do a challenge dose

Edrophonium (Tensilon) challenge -tensilon is a cholinesterase inhibtor that is short-acting. If MC, condition will improve
A Tensilon test is a diagnostic test used to evaluatemyasthenia gravis, which is a neuromuscular condition characterized bymuscle weakness. The test involves an injection of Tensilon (edrophonium), after which your muscle strength is evaluated to determine whether your weakness is caused by myasthenia gravis or not.