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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

Tiotropium blocks proinflammatory action of ACh, but allows

ACh to inhibit ACh release