Chapter 20 Flashcards
Cholinergic drugs are also known as ______ or _______
cholinergic agonists; parasympathomimetics
What do cholinergic drugs mimic
PSNS neurotransmitter ACh
PSNS is “flight or fight” or “rest and digest”
rest and digest; SNS is fight or flight
…they’re opposites.
Cholinergic drugs stimulate which system
PSNS
What are cholinergic effects (SLUDGE)
increased Salivation Lacrimation Urination Diarrhea increased GI motility possible Emesis
How do direct-acting cholinergic agonists work?
Bind directly to cholinergic receptors and activate them
How do indirect-acting cholinergic agonists work? (Long)
stimulate the postsynaptic release of ACh at the receptor site. This then allows ACh to bind to and stimulate the receptor. Inhibit the enzyme acetylcholinesterase, which breaks down ACh -> more ACh available at the receptors
What are the two types of receptors:
Nicotinic and Muscarinic
Where are Nicotinic receptors; how do they get their name
located in ganglia of PSNS and SNS; can be stimulated by alkaloid nicotine found in tobacco plant
Where are muscarinic receptors; how do they get their name
located postsynaptically in effector organs of PSNS (sm. mu., cardiac muscle, glands); can be stimualted by the alkaloid muscarine isolated form mushrooms
What are the 2 mechanisms of action for cholinergic agonists?
Direct-acting vs. indirect-acting
How do Indirect-acting (cholinesterase Inhibitors) bind to cholinesterase? (2 ways)
Reversible: bind to cholinesterase for minutes to hours
Irreversible: bind to cholinesterase and form a permanent covalent bond; body must make new cholinesterase in order to break these bonds
What are drug effects of cholinergic drugs? (simple)
Stimulate: intestine, bladder, pupils
Increases: salivation, sweating
Cardiovascular effects
Respiratory effects
Drug effects of cholinergic drugs (have fun with this one)
Stimulate intestine/bladder:
+ gastric secretions
+ GI motility
+ urniary freq.
Stimulate pupils:
mydriasis
-intraocular pressure
+salivation/sweating
Cardiovascular effects:
- HR
vasodilation
Respiratory effects:
bronchial constriction
- means increase, - means decrease/reduced
What receptors do cholinergics affect at recommended vs. high doses? Which are desirable?
recommended doses: affect muscarinic receptors *desirable
high doses: stimulate nicotinic receptors *undesirable
Indications of direct-acting drugs
- intraocular pressure
useful for glaucoma/intraocular surgery, topical application (eyedrops)
Bethanechol (drug name)
+tone/motility of bladder/GI tract, relaxes sphincters -> allows it to empty
usually oral dose or SQ injection
Indications of indirect-acting drugs
cause sk. mu. contractions
used for diagnosis/treatment of myasthenia gravis
reverses neuromuscular blocking drugs and anticholinergic poisoning (antidote, physostigmine)
*Donepezil (Aricept): treats mild to moderate alzheimer’s
Memantine/Namenda: not cholinergic, also treats alzheimers blocks stimulation at NMDA receptors (reduces symptoms)
What results in adverse effects?
Overstimulation of the PSNS
5 systems, and specifics, of adverse effects
Cardiovascular: bradycardia, hypotension, conduction abnormalities (AV block and cardiac arrest)
CNS: h/a, dizziness, convulsions
GI: ab cramps, +secretions, nau, vom
Respiratory: +bronchial secretions, bronchospasms
Other: Lacrimation, sweating, salivation, loss of binocular accommodation,
When cholinergic drugs interact with anticholinergics, antihistamines, and sympathomimetics, what happens?
antagonize cholinergic drugs = decreased responses
when cholinergic drugs interact with other cholinergic drugs, what happens?
additive effects?
ex. instead of 1+1=2, 1+1=6
3 common uses of Gingko
- organic brain syndrome
- vertigo
- tinnitus
Adverse effects of Gingko
GI upset, h/a, bleeding, allergic skin reactions
h/a:headache
Drug interactions of Gingko
aspirin, NSAIDs, anticoagulants, anticonvulsants, others
Cholinergic drugs stimulate the _______ and mimic the action of _____
PSNS; ACh
3 things to teach pt’s taking cholinergic drugs:
- take as ordered, do not abruptly stop
- change positions slowly (prevent dizzinezz/fainting)
- overdosing can cause life-threatening symptoms, do not adjust dosages unless directed by a physician
What is the antidote for cholinergics, and where should it be kept?
Atropine; should be available in the pt’s room for immediate use if needed
Which pt’s need to take medication 30 minutes prior to eating and why?
pt’s with myasthenia gravis; help improve chewing and swallowing
2 important things to tell those receiving alzheimer’s meds
- drugs are for management of symptoms, it is not a cure
2. therapeutic effects may not occur for 6 weeks
When monitoring for therapeutic effects, what’re you looking for in:
- pt’s with myasthenia gravis
- postoperative pts with decreased GI peristalsis
- pt’s with urinary retention/hypotonic bladder
- alleviated s/s of myasthenia gravis
- increased bowel sounds; passage of flatus; occurrence of bowel movements
- urination should occur within 60 minutes of bethanechol administration
