Chapter 21 Cholinergic-blocking drugs Flashcards
By blocking the Cholinergic drugs, we are essentially having what type of effects
sympathetic effects (blocking ACh from binding and having it's cholinergic effects, allows the sympathetic NS to dominate)
Give two other names for Cholinergic blockers
- anticholinergics
* parasympatholytics
What do cholinergic blockers do?
block the actions of acetylcholine at the muscarinic receptor in the PSNS
What happens to ACh when it is released from the stimulated site but then cannot attach to the muscarinic receptor site due to the cholinergic blocker drug?
it will not bind and therefore fails to have it’s cholinergic effect
Cholinergic blockers are competitive antagonists, what are they competing with?
ACh
Once chilinergic-blockers bind to receptors, what do they inhibit at these receptors?
nerve transmission
What do cholinergic blockers block, at which specific receptors, in which specific nervous system?
(answer all three questions)
- block ACh
- at muscarinic receptors
- in PSNS
Is the preganglionic fiber short or long?
Is the postganglionic fiber short or long?
- pre= long
* post= short
Where is the nicotinic receptor found?
Ganglion
At which type of receptor site do cholinergic-blockers have little effect on?
(only in high doses they have partial blocking effects)
Nicotinic receptors
Where does the cholinergic -blockers binding to receptors occur mainly?
neuroeffector junction, or where the nerve ending reaches effector organs such as smooth muscle, cardiac muscle and glands
What are the drug effects for cholinergic-blockers on the CNS?
small dose: ?
large dose: ?
small dose: decrease muscle rigidity and tremors
Large dose: drowsiness, disorientation, hallucinations
What are the drug effects for cholinergic-blockers on the Cardiovascular?
small dose: ?
large dose: ?
small dose: decrease heart rate
large dose: increase heart rate
What are the drug effects for cholinergic-blockers on the Respiratory?
decreased bronchial secretions
dilated bronchial airways
Since these drugs have little effect at nicotinic receptors, the majority of the site of action takes place at the
heart respiratory tract GI tract Bladder eye exocrine glands
These drugs have the opposite effect of cholinergic drugs (ex: so there is blockade of ACh)
true or false?
true
List this drugs effects on the eye
- Dilated pupils (mydriasis)
* decreased accommodation caused by paralysis of ciliary muscles (cycloplegia)
List the drug effects on the GI
- relax smooth muscle tone of GI tract
- decrease intestinal and gastric secretions
- decrease motility and peristalsis
List the drug effects on the genitourinary
bladder
- relaxed detrusor muscle
- increased constriction of internal sphincter
- result: urinary retention
drug effects on glandular?
decreased bronchial secretions, salivation, sweating
What are the indications for the CNS?
(cholinergic blockers)
(on test)
decreased muscle rigidity and muscle tremors
- Parkinson’s Disease
- Drug-induced extrapyramidal reactions
Why do we use these drugs for the cardiovascular system (indications) ?
low dose effect: ?
high dose effect: ?
they can effect the heart’s conduction system
lose dose: slow the HR
high dose: Block inhibitory vagal effects on SA and AV node pacemaker cells (because vagal effect normally reduces HR)
* results in increased (+) HR
What is Atropine primarily used for?
CV disorders (normally used when patient is coding (Cardiac Arrest)
What are the results to be expected from this drug when used for Respiratory?
- decreased secretion from nose, mouth, pharynx, bronchi
- relaxed smooth muscle in bronchi/bronchioles
- decreased airway resistance
- Bronchodilation
Name for things that cholinergic blockers are used to treat
- exercise induced bronchospasms
- Chronic bronchitis
- Asthma
- COPD
Blocking the Cholinergic stimulation of the PSNS allows for unopposed action of the ___
SNS (sympathetic NS)
When Cholinergics are working on the GI system, rest and digest is happening so there are secretions, contractions in smooth muscle, GI motility and peristalsis. So when a cholinergic-blocker does its job and blocks cholinergic effect, what happens to the GI?
the opposite
decrease secretions
relaxation of smooth muscle
decreased GI motility and peristalsis
Name two issues that cholinergic-blockers are used to treat
- IBS (irritable bowel syndrome)
* GI hypersecretory states
If cholinergic-blocker drugs interact with antihistamines, phenothiazines, tricyclic antidepressants, or MAOIs, what is the outcome?
it increases the cholinergic effect (does the opposite of what they are meant for)
Nursing Implications for cholinergic-blockers. What do we need to know about patient
assess for
- allergies
- presence of BPH
- glaucoma
- tachycardia
- MI, HF, Hiatal hernia
- GI or GU obstruction
- baseline assess/ Vital signs
When giving opthalmic solutions, what should you do to prevent systemic absorption?
apply pressure to inner canthus
What is the antidote from Atropine overdose?
physostigmine
Anticholinergics taken by edlerly patients may increase risk for what?
heat stroke (emphasis importance of adequate fluid and salt intake)
therapeutic effects for patients with Parkinson’s?
- fewer tremors
* decreased salivation and drooling
therapeutic effects for patients with urologic problems?
- improved urinary patterns
- less hypermotility
- increased time between voiding
