Flashcards in Cholinergics Deck (38)
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1
M3 receptor parasympathetic effects
contraction in eye (decrease IOP), urinary contraction (increase micturition), contraction of the gut (increase motility), contraction of lung (bronchoconstriction)
2
M1 receptor effects
parasympathetic stimulation of mucosal glands (increase secretion)
3
M3 sympathetic effects
increase sweat gland secretion
4
M2 receptor effects
(parasympathetic) ↓ contraction & ↓ conduction of heart (↓ bp, bradycardia)
5
M3 receptor other effects
vascular endoyhelium: ↓ bp, Reflex tachycardia (no innervation)
6
Direct-Acting Cholinomimetic: Mechanisms of Action and Pharmacology
Activate muscarinic receptors
Affect all muscarinic receptor subtypes
Mainly evoke parasympathomimetic effects
Mild or no desensitization
7
Bethanechol
Choline Ester (charged), not used to treat glaucoma (Charged molecules like bethanechol unable to adequately penetrate to the eye ciliary muscle)
8
Pilocarpine
Alkaloid (uncharged, lipophilic), used to treat glaucoma
9
Direct-Acting Cholinomimetic drugs
Bethanechol & Pilocarpine
10
Direct-Acting Cholinomimetic drug negative effects
Parasympathetic effects:
Dizziness, headaches, bronchospasms, hypotension and reflex tachycardia, secretion, lacrimation, miosis, abdominal cramps, nausea, vomiting, diarrhea, urinary urgency, sweating
11
Direct-Acting Cholinomimetic drug Precautions/Contraindications
Asthma, COPD, peptic ulcer, hypotension
12
Direct-Acting Nicotinic Agonists
nicotine (an alkaloid)
13
Can Nicotinic Acetylcholine Receptors become desensitized?
yes; with a prolonged agonist
14
Direct-Acting Nicotinic Agonists stimulate
CNS, all peripheral ganglia and skeletal muscle (NMJ)
15
Major clinical use of Direct-Acting Nicotinic Agonists
Smoking cessation
16
Antimuscarinics: Mechanisms of Action and Pharmacology
Inhibit muscarinic receptors
Drugs available clinically generally act on all receptor subtypes*
Evoke parasympatholytic effects
17
No innervation of muscarinic receptors in vasculature (except coronary arteries). Only effected by
‘circulating’ muscarinic agents. No agonist (ACh) -->No effect of antagonist. Antagonist effect only seen with ‘circulating’ muscarinic agents
18
Quaternary amines such as __________, have poor absorption
Ipratropium (which treats asthma)
19
Clinical Use of Antimuscarinics for Asthma
Atropine (3o)(no longer used), Ipratropium (4o) (inhaled)
Tiotropium (4o) (inhaled) (Bronchospasm in Chronic obstructive pulmonary disease (COPD), and asthma)
20
ACh activates neuronal _________ as negative feedback control of ACh release
M2 receptor
21
Ipratropium increases
ACh release from nerve
22
Tiotropium blocks
M3 but not M2 receptors.
23
A low dose atropine __________, but a higher dose _________.
increases ACh release(decreases HR); decreases ACh release (increase HR)
24
Toxic effects of muscarinic antagonists
Blurred vision, photosensitivity; Agitation, hallucinations,
delirium, coma; Tachycardia, angina; Dry mouth, nasal
congestion, hot/flush skin, hyperthermia; Dysuria, retention; Nausea, distention, cramps, constipation
“Dry as a bone, blind as a bat, red as a beet, mad as a hatter, and hot as a hare.”
25
Why are MUSCARINIC ANTAGONISTS CONTRAINDICATED FOR OPEN-ANGLE GLAUCOMA?
Atropine prevents activation of M3
decreases humor outflow → increases IOP
26
General Classes of Cholinesterase Inhibitors
reversible-4o Alcohols & Carbamates; irreversable-organophosphates
27
Edrophonium
a 4o Alcohol; reversible Cholinesterase Inhibitor that binds to choline subsite and H+ bond to acyl pocket
28
Physostigmine
a Carbamate; reversible Cholinesterase Inhibitor that binds like ACh with covalent bond, decarbamoylation rate slower than deacetylation rate.
29
Physiological effects of inhibiting cholinesterase
increase EEG and Alertness, Parasympathomimetic
Bradycardia, Stimulation, Low dose: indirect decrease in BP; Higher dose: increased Symp drive, increased strength, Similar to direct acting cholinomimetics
30
In Myasthenia Gravis, you can use _______ for an eye test– rapid short acting, prevents fatigue of eyelid muscle and use _______ as a treatment
Edrophonium;
Physostigmine
31
toxic effects of cholinesterase inhibition
increase EEG and Alertness, Convulsions -->Coma; Parasympathomimetic effects on heart; depression; hypotension; blockade of skeletal muscle; Similar to direct acting cholinomimetics
32
Myasthenia Crisis Vs. Cholinesterase Crisis
Myasthenia Gravis is limited to the NMJ
33
AChE Inhibitors used to treat Muscarinic Inhibitor poisoning and
vice versa
34
Reversible AChE inhibitor used to treat
AChE Inhibitor poisoning
35
Direct-acting cholinomimetics
Bethanechol, Pilocarpine, Acetylcholine, Nicotine
36
reversible indirect-acting cholinomimetics
Edrophonium, Physostigmine, Echothiophate
37
muscarinic inhibitors
Atropine, Ipratropium, Tiotropium
38
