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Pharmacology > Lecture 3 - Adrenergics & Cholinergics - NICOLE > Flashcards

Lecture 3 - Adrenergics & Cholinergics - NICOLE Flashcards

1
Q

alpha 2 agonists are sedatives and analgesics that

A

DECREASE CARDIAC OUTPUT

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2
Q

alpha 2 agonists characteristics (good for what vs bad for what)

A

-good premeds for anesthesia
-good for standing procedures
- bad in patients with compromised CV function

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3
Q

reducing dose of alpha 2 agonists does NOT reduce

A

the magnitude of the adverse effects on cardiac output, but does reduce the duration of these effects

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4
Q

how do alpha 2 agonists provide sedation and analgesia?

A

-sedation due to inhibition of NE release in brainstem
- analgesia due to reduced neurotransmitter release and signal transmission in afferent pathways

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5
Q

how do alpha 2 agonists reduce cardiac output? (long one sorry)

A
  1. Initial effect on blood vessels is vasoconstriction which increases blood pressure (also increases after load which decreases cardiac output).
  2. The increase in bl. pres. is sensed by baroreceptors, which triggers a decrease in sympathetic tone and an increase of parasympathetic tone.
  3. Increased parasympathetic tone to the heart will slow the heart rate to reduce cardiac output (BRADYCARDIA that results from alpha 2 agonism)
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6
Q

xylazine is a(n)

A

alpha 2 agonist

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7
Q

xylazine is commonly used in

A

horses and ruminants

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8
Q

do horses or cows get more xylazine

A

ruminants take approx 1/10th the horse dose to achieve the same effect

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9
Q

do you use xylazine on sick animals

A

generally reserved for healthy animals

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10
Q

side effects of xylazine an alpha 2 agonist

A

AV block, reduced GI motility, sweating, increased myometrial tone

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11
Q

how do you reverse xylazine

A

yohimbine or atipamezole

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12
Q

clinical tips for xylazine

A

combine with butorphanol (opioid) for better sedation and pain control
use caution with xylazine in late pregnant animals, increased risk of premature delivery

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13
Q

the alpha 2 agonists commonly used in large animals are

A

xylazine, detomidine, and romifidine
(listed in order of intensity of cardiovascular effects)

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14
Q

alpha 2 agonists tend to have a

A

diuretic effect

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15
Q

sedation with xylazine compared to detomidine in horses

A

serum half life of xylazine is longer (50 mins) and detomidine is 25 mins but sedation is deeper and more reliable than sedation with xylazine
CV effects (bradycardia and bradyarrythmias) are more pronounced after detomidine than xylazine

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16
Q

sedation with romifidine in horses

A

serum half life of 135 minutes in horse
tends to cause less ataxia in horses than other alpha 2 agonists, so may be preferred for procedures such as standing mri where the horse standing still and not swaying is important
however its more expensive

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17
Q

alpha 2 agonists sedative vs analgesic effects time

A

analgesic effects do not last as long as sedative effects - alpha 2 agonists are selective, not specific for alpha 2 receptors so they also have some binding to alpha 1 receptors

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18
Q

detomidine potency vs xylazine

A

50-100 times more potent than xylazine

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19
Q

what do you primarily use xylazine in

A

horses but can be used in cattle

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20
Q

does xylazine or detomidine have better sedation and pain control for surgery

A

detomidine

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21
Q

is detomidine or xylazine LESS likely to cause premature delivery in pregnant animals?

A

detomidine

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22
Q

how do you reverse detomidine?

A

an alpha 2 antagonist such as atipamezole

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23
Q

dexmedetomidine is a

A

alpha 2 agonist

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24
Q

dexmedetomidine is similar to

A

medetomidine

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25
Q

what is dexmedetomidine used commonly for

A

small animals getting procedures that require sedation

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26
Q

dosage of dexmedetomidine is based on

A

body surface area

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27
Q

when used as a premed dexmedetomidine reduces

A

maintenance anesthetic needs

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28
Q

how to reverse dexmedetomidine

A

alpha 2 antagonist - atipamezole

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29
Q

clinical tip dexmedetomidine

A

makes over 50% of cats vomit

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30
Q

dexmedetomidine is the most selective of

A

alpha 2 agonists. it has an alpha 2: alpha 1 selectivity of 1620:1 (10x better than xylazine)

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31
Q

most common alpha 2 agonists used for sedation in small animal practice

A

dexmedetomidine and medetomidine (dexdomitor and domitor, respectively)

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32
Q

dexmedetomidine and meditomidine are enantiomers

A

compounds that are mirror images and rotate polarized in opposite directions.

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33
Q

dexmedetomidine vs metomidine pharmacodynamics and dose

A

similar pharmacodynamic effects but dose of metedomidine required to exert a clinical effect approximately twice the dose of dexmetedomidine required to exert the same effect (bc half the molecules of med are in inactive form)

they have similar efficacy but dexmed is more potent

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34
Q

most concerning alpha 2 agonist side effects

A

cardiovascular effects

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35
Q

alpha 2 agonists will decrease

A

cardiac output

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36
Q

alpha 2 agonists - initial vasoconstriction leads to bradycardia then presynaptic effects can then lead to

A

vasodilation so we get hypertension, followed by vasodilation. however, the bradycardia is generally persistent

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37
Q

best to use alpha 2 agonists in

A

HEALTHY animals.

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38
Q

DO NOT use alpha 2 agonists in

A

animals with CV disease or in shock

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39
Q

alpha 2 agonists - good analgesia but shorter than

A

the sedative effect

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40
Q

alpha 2 agonists have better sedation and analgesia when paired with an

A

opoid

41
Q

can paradoxical excitement occur with alpha 2 agonists

A

yes - common to get xylazine rage

42
Q

what is dobutamine

A

beta 1 agonist

43
Q

dobutamine is a positive

A

inotrope that does NOT increase heart rate (at normal doses) but does increase stroke volume

44
Q

half life of dobutamine

A

2 minutes

45
Q

is dobutamine pricey

A

yes

46
Q

adverse effects of dobutamine

A
  • correct hypovolemia before administration
  • incompatible with bicarbonate
    -at high doses can cause tachycardia
    -seizures in cats! use low doses only, if at all
47
Q

dobutamine is sometimes used to

A

raise blood pressure in anesthetized patients.

48
Q

dobutamine activates what receptors

A

dopamine, alpha 1, and beta 1 receptors (causing vasoconstriction and increasing intropy)

49
Q

clenbuterol is a

A

beta 2 agonist

50
Q

can you give clenbuterol to food animals

A

NO YOU CANNOT !!! DONT DO IT

51
Q

clenbuterol has what effects

A

-bronchodilator (rarely used now to treat equine asthma)
-inhibits uterine tone/contractions (aids in dystocia)

52
Q

clenbuterol is banned in food animals because

A

used to be used as a growth promotant but residues in meat have caused tachycardia, muscle tremors, and headaches in consumers

53
Q

epinephrine is a

A

non selective adrenergic agonist

54
Q

epinephrine is used for

A

emergency treatment of anaphylaxis or for cardiopulmonary resuscitation

55
Q

epinephrine is sometimes added to local anasthetics to

A

cause vasoconstriction

56
Q

epinephrine increases cardiac output but also

A

myocardial oxygen consumption

57
Q

you can give epinephrine

A

IV, IM, SC, IT

58
Q

in anaphylaxis, epinephrine is given for its

A

vasoconstrictive (alpha 1) and bronchodilator (beta 2) effects and is very useful

59
Q

in CPR situations, epinephrine is indicated when

A

the animal has a non-shockable rhythm and that only low-dose epinephrine is now recommended

60
Q

prazosin is an

A

alpha 1 antagonist

61
Q

prazosin has what effects

A

reduces blood pressure - arterial and venous vasodilatory
- sometimes used as adjunctive treatment for heart failure but there are better choices

62
Q

prazosin is no longer recommended for

A

blocked cats !!!!!!!!

63
Q

why is prazosin no longer used for blocked cats

A

it was often given after unblocking for several weeks to decrease urethral spasms but recent evidence shows this may INCREASE the risk of reblocking :(

64
Q

is prazosin protein bound?

A

yes - 97% protein bound

65
Q

atipamezole is an

A

alpha 2 antagonist

66
Q

atipamezole is a competitive inhibitor of

A

alpha 2 receptors

67
Q

atipamezole clinical effects

A

reverses sedation, cardiovascular effects, and analgesia associated with alpha 2 agonist administration

68
Q

atipamezole is normally administered

A

IM in small amounts

69
Q

in horses atipamezole is normally given

A

1/2 IM and 1/2 IV and IV is injected SLOWLY

70
Q

cats are often castrated under an injectible anesthetic combo of dexmed, butorphanol, and ketamine. If reversing this after the procedure, make sure that

A

you wait long enough that the ketamine has worn off before administering atipamezole. Also, whenever you reverse an alpha 2, consider pain control as you’re also reversing the alpha 2 analgesic effect

71
Q

esmolol is a

A

beta 1 antagonist

72
Q

esmolol is an ultra short acting IV

A

beta blocker

73
Q

esmolol is used to treat

A

supraventricular tachycardias or to test if beta blockers will be effective in controlling arrthymias (esp in cats with HCM)
- anesthesia
-CPR

74
Q

esmolol is a negative

A

inotrope and chronotrope

75
Q

esmolol may

A

decrease myocardial oxygen demand
reduces systolic and diastolic blood pressure

76
Q

esmolol adverse effects

A

hypotension and bradycardia

77
Q

drugs that act similarly to acetylcholine are called

A

parasympathomimetics / cholinergics / cholinoreceptor stimulants

78
Q

neostigmine is a what

A

cholinergic

79
Q

neostigmine is a reversible

A

inhibitor of acetylcholinesterase

80
Q

neostigmine results in

A

decreased breakdown of Ach at the synaptic cleft and enhanced activity

81
Q

neostigmine is used to increase

A

gut motility/for its smooth muscle effects and is also used in treatment of myasthenia gravis

82
Q

in myasthenia gravis, autoantibodies attach nicotinic Ach receptors in skeletal muscles. This results in

A

muscle weakness.

83
Q

by inhibiting acetylcholinesterase, neostigmine causes

A

more Ach to be available, increasing its interaction with the receptors that are still present and helping to counteract the weakness that results from this disease

84
Q

is neostigmine or pyridostigmine preferred for myasthenia gravis treatment

A

pyridostigmine because it has a longer duration of action and fewer GI effects

85
Q

atropine and glycopyrrolate are what

A

anticholinergics

86
Q

atropine and glycopyrrolate are competitive muscarinic antagonists used to

A

reduce response to parasympathetic nerve impulses

87
Q

effects of atropine and glycopyrrolate are

A

dose dependent

88
Q

atropine and glycopyrrolate increase

A

HR and conduction veolcity , inhibit GI smooth muscle contraction, mydriatic, decrease secretions, and bronchodilator

89
Q

glycopyrrolate and atropine are used for

A

emergency treatment of bradyarrythmias, to facilitate opthalmic exams, such as adjunctive treatment for equine recurrent uveitis

90
Q

adverse effects of atropine and glycopyrrolate

A

primarily tachycardias
at high doses atropine may cause mania
can cause ileus, especially in horses

91
Q

glycopyrrolate or atropine - which one crosses BBB more

A

atropine - so glycopyrrolate has fewer CNS effects

92
Q

the combination of anticholinergics and alpha 2 agonists creates the potential for

A

myocardial hypoxemia to develop as a result of increased myocardial work

93
Q

N-butylscopolammonium bromide/ hyoscine buytlbromide: is an

A

anticholinergic

94
Q

N-butylscopolammonium bromide/ hyoscine buytlbromide is only used in

A

horses but is labelled for cattle in some countries

95
Q

N-butylscopolammonium bromide/ hyoscine buytlbromide has effects similar to

A

atropine

96
Q

N-butylscopolammonium bromide/ hyoscine buytlbromide is especially useful in horses with

A

gas/spasmodic colic (relaxes intestine)
- but heart rate increases after administration and can’t be used to monitor pain for about 30 min

97
Q

N-butylscopolammonium bromide/ hyoscine buytlbromide can be useful for

A

performing rectal exams in horses and for acute asthma treatment

98
Q

N-butylscopolammonium bromide/ hyoscine buytlbromide common name

A

buscopan - used to treat spasmodic colic, relax rectum for rectal exams. ad relax esophageal smooth muscle in choked horses

99
Q
A

Pharmacology (11 decks)

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