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Flashcards in physio pharmacology midterm Deck (62):
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Sildenafil

Viagra! Blocks cGMP phosphodiesterase from breaking down cGMP to 3,5' GMP -> prolonged relaxation of BVs for erection

1

Hemicholinium

Prevents choline reuptake

2

Vesamicol

Prevents vesicular storage of ACh

3

Botulinum toxin

Degrades synaptobrevin (SNARE) and prevents vesicle fusion/exocytosis. Clinically in cases with increased skeletal muscle tone, Lambert-Eaton syndrome, focal dystonias

4

AChE inhibitors

Elevate synaptic concentrations of ACh, therefore enhancing the postsynaptic effects of ACh (parasympathomimetics)

5

Edrophonium

AChE inhibitor/anticholinesterase. Simple alcohol. Short duration of action. Useful for dx'ing myasthenia gravis and Lambert-Eaton syndrome

6

Neostigmine and physostigmine

AChE inhibitor/anticholinesterase. Carbamic acid derivatives. Longer duration of action. Useful for tx'ing MG; reversal of neuromuscular blockers. (Physostigmine crosses BBB - good for CNS eg atropine poisoning.) Hydrolyzed by AChE so that covalent bond forms increasing half life of AChE inhibition

7

Parathion

AChE inhibitor/anticholinesterase. Organophosphate. Irreversible, toxic, commonly used in pesticides. Hydrolyzed by AChE to form an extremely stable complex. Only new recs can facilitate AChR activity and that can take weeks

8

Myasthenia Gravis

Autoimmune dz against Nm subtype (rec internalized), reduces NMJ transmission

9

Lambert-Eaton syndrome

Autoimmune dz against presynaptic Ca2+ channels. Reduces ACh release. Also used in dx

10

AChE inhibitor uses

1. Increase neuromuscular transmission - MG, LE syndrome
2. Increase parasympathetic tone (parasympathomimetic) - decrease glaucoma pressure via increased aq humor outflow, increase GI tract motility
3. Increase central cholinergic neurotransmission in dementia (rivastigmine). Must titrate. Drugs delay development of cognitive and fxn'l impairment by 6 months.
4. Reversal of paralysis from non-depolarizing neuromuscular blockers - increase ACh levels reverse the competitive block from these blockers

11

Negative SE's of AChE inhibitors

1. Excessive muscarinic stim - salivation, lacrimation, miosis, diarrhea, brachycardia
2. Excessive nicotinic stim - muscle wkness and paralysis
3. Chemical warfare - used as nerve gases - sx's include mm wkness and paralysis

12

Dz using muscarinic agonists as txt: eye; GIT, bladder, urinary tract; salivary glands

Eye: glaucoma - contract circular m -> miosis -> aq humor outflow -> decreased intraocular pressure

GIT, bladder, urinary tract: restore GIT and UT motility after anesthesia/surgery

Salivary glands: xerostemia - increase salivation

13

Rivastigmine

AChE inhibitor. Improve dementia and Alzheimer's dz cognitive sx's. Requires titration phase. Drugs delay development of cognitive and fxn'l impairment by six months

14

Carbachol

MR agonist. Derivative of ACh. Differs in pharmacokinetic properties, resistance to ChEsterase and its affinity to both Nm and musc recs. Can't be used systemically because of overall effects

15

Pilocarpine

MR agonist. Alkaloid similar to muscarine. Until recently the only alkaloid MR agonist to be used clinically. Used to tx dry mouth in Sjogrens syndrome

16

Methacholine

MR agonist. 3x more resistant to hydrolysis by AChE. Little affinity for nicotinic recs. used to dx asthma. Asthmatics are more sens to bronchial secreting actions of methacholine

17

Bethanecol

MR agonist. Almost completely selective for muscarinic recs. Choice drug for promoting GI and urinary tract motility. Particularly post-op, post-partum, and drug-related urine retention

18

Parasympatholytics

MR antagonists. Bind MRs and prevent ACh from exerting its effects. Competitive antagonists. Allow sympathetic responses to predominate.

19

Parasympatholytic prototype

Atropine. Actions: pupil dilation, tachycardia, decreased secretions (salivary, bronchial, GIT). Sympathetic response by antagonizing the parasympathetic

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Clinical uses of atropine

1. Produce mydriasis for opthalmological exam (applied topically)
2. Reverse sinus brachycardia caused by excessive vagal tone
3. Inhibit excessive salivation and mucus secretion during anesthesia and surgery
4. Counteract the effects of muscarine poisoning AND poisoning with anticholinesterases

21

Scopolamine

MR antagonist. Significant CNS. Txt of nausea and motion sickness, intestinal cramp. As a general depressant and adjunct to narcotic painkillers. Truth drug in 50s and 60s

22

Pirenzepine

MR antagonist. Txt of peptic ulcers, an alternative to H2 histamine rec antagonists

23

Ipratropium

MR antagonist. Relatively selective for M3. Reduces bronchial secretions - used in COPD. Used in asthma where the bronchoconstrictive component is mediated by increased cholinergic neural tone

24

Succinylcholine

Nicotinic rec depolarizing neuromuscular blocker. Causes excessive activation of Nm rec leading tie widespread muscle fasciculations. Eventual desensitization of Nm rec leading to muscle paralysis.

Uses: short term paralysis, ie during intubation. Short duration bc of merabolism by pseudocholinesterases (BuChE)

SE's and adverse rxns: brachycardia (M2), K+ release (from prolonged depolarization), prolonged paralysis (genetic variants of pseudocholinesterase), malignant hyperthermia

25

Nicotinic rec antagonists: non-depolarizing neuromuscular blockers

Uses: paralyze skeletal muscles during surgery

Mode of action: occupy Nm recs on skeletal muscle. Have no intrinsic activity. Prevent the action of ACh. Muscle can't contract. Flaccid paralysis

Competitive antagonists: therefore, effects are overcome by increasing ACh levels.
Reversal achieved by AChE inhibitor

26

D-tubocurarine

Non-depolarizing (competitive) neuromuscular blocker. Plant alkaloid ("arrow poison")

27

Pancuronium

Non-depolarizing (competitive) neuromuscular blocker. Long acting

28

Vecuronium

Non-depolarizing (competitive) neuromuscular blocker. Intermediate duration

29

Mivacurium

Nicotinic rec antagonist Non-depolarizing (competitive) neuromuscular blocker. Short acting

30

Uses and SE's of nicotinic rec antagonist non-depolarizing (competitive) neuromuscular blockers

More selective on Nm rec than Nn rec (ganglia)!!!

Uses: induction of neuromuscular blockade in surgery

SE's: hypertension, apnea, bronchospasm, salivation, flushing, and resp failure

31

Oxymetaxoline

a1 agonist, partial a2 agonist. Nasal decongestant. Tx Ophthalmic hyperaemia (too much bloodflow to eye).

32

Phenoxybenzamine

a1 and a2 antagonist. Irreversible. Tx pheochromocytoma

33

Phentolamine

Alpha antagonist. Reversible antagonist. Tx pheochromocytoma

34

Phenylephrine

Alpha 1 agonist. Used as nasal decongestant. Can also be used for treatment of shock

SE's: hypertension

35

Prazosin

Alpha 1 antagonist. Used for txt of hypertension and BPH.

SE's: postural orthostatic/hypotension related to 1st dose phenomena

36

Tamsulosin

Alpha 1 antagonist. Used for BPH. More selective for genitourinary smooth muscle receptor subtype (a1A). Less postural/orthostatic hypotension

37

Clonidine

Alpha 2 agonist. Used to tx hypertension (decreased peripheral sympathetic outflow - CNS effect) and opioid withdrawal

SE's: brachycardia and hypotension

38

Yohimbine

Alpha 2 antagonist. Previously used for male impotence (psychogenic).

SE's: increased sympathetic outflow - hypertension

39

Isoproterenol

Nonselective B receptor agonist. Emergency arrhythmias and bronchospasm. More selective agonists available.

SE's: hypertension, palpitations, tremor

40

Dobutamine

Selective B1 receptor agonist. Has prominent inotropic effects resulting in increased contractility and cardiac output. Short half-life due to COMT metabolism. Used in the ACUTE management of heart failure (Note more than just B1 activity). Increased contractility but NOT heart rate - no change in peripheral resistance

41

Albuterol

Selective B2 receptor agonist. Used as asthma reliever. Rapid action (15 minutes), relative short duration (4-6 hours)

42

Salmeterol

Selective B2 receptor agonist. Long-acting beta agonist (LABA's). Have lipophilic side chains that resist degradation. Enhanced duration (12-24 hours), used for prevention of bronchoconstriction

43

B adrenergic antagonists: clinical uses

Reduce chronotropic and inotropic actions of endogenous catecholamines at cardiac B1 receptors, resulting in decreased heart rate and myocardial contractility. Blockade of B1 recs in kidney to reduce renin secretion to reduce fluid overload and vasomotor tone. Are first line drugs in txt of hypertension. Blockade of B2 receptors is clinically undesirable

44

Propranolol

Non-selective B adrenoreceptor antagonist. Used for hypertension, angina

SE's include sedation (central effect) and dyspnea

45

Atenolol

B1 selective adrenergic antagonist. Used to tx hypertension and angina. Improves life expectancy in patients with heart failure (via volume reduction (decreased afterload) via decreased renin production. Contraindications

46

Pindolol

Partial B1 agonist. Tx hypertension in patients with brachycardia or low cardiac reserve

47

Carvedilol

Nonselective B and a1 antagonist. a1 receptor blockade results in vasodilation; the B1 blockade prevents a reflex sympathetic increase in heart rate. These effects combine to decrease blood pressure. Also used in txt of heart failure. Contraindicated in severe HF

Clinical benefit in HF through volume reduction (decreased afterload) via decreased renin production and vasodilation (decreased preload)

48

Cocaine

Inhibitor of NE reuptake by inhibiting NE transporter

49

Tricyclic antidepressants (TCA's)

Inhibitor of NE reuptake. Inhibit NE transporter

50

Imipramine

Inhibitor of NE reuptake. TCA. Inhibits NE transporter. Used for treating mild depression

SE's: postural hypotension and tachycardia

51

Reserpine

Inhibitor of NE storage. Blocks VMAT

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Tyramine

Inhibits NE storage. Transported VMAT and displaces vesicular NE

53

MAO inhibitor uses

Txt of mild depression

54

Phenelzine

Inhibitor of NE metabolism. Non-selective MAO inhibitor. Implicated in elevated tyramine leading to hypertensive crisis

55

Selegiline

Inhibitor of NE metabolism. Selective MAO B inhibitor. Safer with respect to dietary restriction. Also useful for Parkinson's

56

Iproniazide

MAO inhibitor

57

Possible acute complications of MAO inhibitors

If you eat aged cheese and red wine that have high conc of tyramine, tyramine is substrate for VMAT -> outcompetes NE for transport into vesicles -> high NE conc in cytosol and reversal of NET -> sympathetic overload - headache, nausea, high BP and pulse

58

Amphetamines

1. Displaces endogenous catecholamines from storage vesicles
2. Blocks NET
3. A weak inhibitor of MAO

59

Methylphenidate

Inhibitor of reuptake and storage of NE. Used for ADHD.

60

Ephedrine and pseudoephedrine

Inhibitors of NE reuptake and storage. Used for nasal decongestion

61

Digoxin

Blocks Na+ K+ ATPase -> higher intracellular conc of Na+ -> reduced activity of Na+ Ca2+ exchanger -> more intracellular Ca 2+ -> increased heart contractility. Used to tx heart failure