Flashcards in Exam II: Cholinergic Antagonists Deck (43):
What are the two groups of anticholinergics? (Cholinergic antagonists)
What are muscarinic antagonists also called?
Parasympatholytic or antimuscarinic
An example of a parasympatholytic or antimuscarinic is...
Describe the actions of atropine
1. Reversibly block muscarinic receptors
2. Typically block actions of exogenously administered cholinergics > endogenous acetylcholine
What tissues are most sensitive to atropine?
What are the tissues effected by atropine?
Examples (3) of nicotinic anticholinergics
Which antimuscarinic is better to elicit CNS effects: atropine or scopolamine?
Atropine is hydrophillic and cannot cross BBB well so it has a minimal effect
What does scopolamine cause at therapeutic doses? At toxic doses?
--> amnesia (if pt is sensitive)
--> CNS excitement
What are two common therapeutic uses for antimuscarinic agents?
Treatment of Parkinson's Disease
Treat motion sickness
What drug(s) are used in tx of Parkinson's Dz
Benzotropine (antimuscarinic agent) along with a dopamine precursor drug (levodopa)
What drug(s) are used to treat motion sickness
(injected, oral, or transdermal patch)
What effects do antimuscarinics have on the eye?
1. Relax papillary constrictor --> mydriasis (dilation of eyes)
2. Relax ciliary muscle --> cycloplegia (loss of accommodation)
3. Reduces lacrimal secretion --> dry eyes!
Are antimuscarinincs indicated in patient's w/ narrow angle galucoma?
Why would we use an antimuscarinic on the eye?
Useful for ophthalmologists to view the retina with the eye dilated and cycloplegia (given as drops)
If given a low dose (0.5 mg) of an antimuscarinic (atropine) what would you observe in the CV system?
Low doses only block M1 receptors; M3 receptors still stimulated by ACh on SA node to create slowed HR
If given a medium to high dose (1-5 mg) of an antimuscarinic (atropine) what would you observe in the CV system?
Blocks M2 receptors in SA and AV nodes, which usually slow HR
If given a toxic dose ( > 10 mg) of atropine what would you observe in the CV system?
Intraventricular conduction block that inhibits electrical pulse generation in pacemaker nodes
--> leads to death
What are some therapeutic uses for antimuscarinics in the cardiovascular system?
Increase HR in pts w/ acute MI, SA or AV node dysfunction in which there is an unwanted bradycardia
What dose level should be used to treat patients with unwanted bradycardia?
Moderate doses of atropine so as to block M2 receptor
What effects do antimuscarinics have on the respiratory system?
1. Cause bronchodilation
2. Reduce/dry up secretions
What two respiratory diseases are treated with antimuscarinics. What are the two drugs used to treat these diseases?
COPD and Asthma
Ipratropium or tiotropium used in inhaler or nebulizer form
What drugs are useful to dry up respiratory secretions?
Atropine or scopolamine
List the effects of antimuscarinic drugs on the GI tract
- Reduced motility, prolonging gastic empthying
- Reduce salivary secretion --> xerostomia
- Reduce GI secretions
Therapeutic uses for GI Tract?
- Treating diarrhea
( mixed with diphenoxylate to create Lomotil )
What is the main effect that antimuscarinic drugs have on the GU system?
Reduce voiding --> by relaxation of detrusor muscle
What are antimuscarinic drugs used to treat in the GU system?
List the common antimuscarinic drugs used to treat urinary incontinence
* Selective M3 receptor antagonist
What are antimuscarinincs used for in terms of sweat gland dysfunctions?
**Not always effective though b/c of the different glands (eccrine and apocrine)
Drug used to treat hyperhidrosis?
How do you treat a patient with rapid onset mushroom poisoning compared to a patient with delayed onset mushroom poisoning?
Give atropine to rapid onset patient
Use supportive care with delayed onset (atropine won't work)
Name side effects of anticholinergics
3. Hot, flushed skin
4. Dry mouth
6. Urinary retention
7. Visual changes
What are 3 contraindicated uses of anticholinergics?
1. Patient's w/ glaucoma
2. Elderly men w/ hx of benign prostatic hyperplasia
3. Pt's w/ gastic ulcers
Toxins from Clostridium botulinum are used to treat what 3 "conditions"
1. Belpharospasm and other focal muscle spasms
2. Hyperhidrosis of palms and axillae
3. Cosmetic removal of wrinkles
Ganglionic Blocking Agents block ____ at _______________.
nicotnic receptors at parasympathetic and sympathetic ganglia
Are ganglionic blocking agents used as therapy? Why or why not.
No, they are mostly used in research since they have both parasympathetic and sympathetic effects, their outcomes are hard to predict.
What do neuromuscular blockers do?
They block neuromuscular transmission between motor end plates and nicotinic receptors on skeletal muscle
________ block neuromuscular transmission between motor end plates and nicotinic receptors on skeletal muscle.
What are the two groups of neuromuscular blockers?
1. Nondepolarizing (antagonists)
2. Depolarizing (agonists)
Nondepolarizing neuromuscular blockers are _______ and therefore can be terminated with _______ because they increase ACh.
AChE inhibitors (neostigmine)
What are nondepolarizing neuromuscular blockers typically used for therapeutically?
Surgery - as adjuncts to anesthesia
What are depolarizing neuromuscular blockers typically used for therapeutically?
Electroconvulsive shock therapy
*Short duration and rapid onset