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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
what is dexmedetomidine used commonly for
small animals getting procedures that require sedation
26
dosage of dexmedetomidine is based on
body surface area
27
when used as a premed dexmedetomidine reduces
maintenance anesthetic needs
28
how to reverse dexmedetomidine
alpha 2 antagonist - atipamezole
29
clinical tip dexmedetomidine
makes over 50% of cats vomit
30
dexmedetomidine is the most selective of
alpha 2 agonists. it has an alpha 2: alpha 1 selectivity of 1620:1 (10x better than xylazine)
31
most common alpha 2 agonists used for sedation in small animal practice
dexmedetomidine and medetomidine (dexdomitor and domitor, respectively)
32
dexmedetomidine and meditomidine are enantiomers
compounds that are mirror images and rotate polarized in opposite directions.
33
dexmedetomidine vs metomidine pharmacodynamics and dose
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
34
most concerning alpha 2 agonist side effects
cardiovascular effects
35
alpha 2 agonists will decrease
cardiac output
36
alpha 2 agonists - initial vasoconstriction leads to bradycardia then presynaptic effects can then lead to
vasodilation so we get hypertension, followed by vasodilation. however, the bradycardia is generally persistent
37
best to use alpha 2 agonists in
HEALTHY animals.
38
DO NOT use alpha 2 agonists in
animals with CV disease or in shock
39
alpha 2 agonists - good analgesia but shorter than
the sedative effect
40
alpha 2 agonists have better sedation and analgesia when paired with an
opoid
41
can paradoxical excitement occur with alpha 2 agonists
yes - common to get xylazine rage
42
what is dobutamine
beta 1 agonist
43
dobutamine is a positive
inotrope that does NOT increase heart rate (at normal doses) but does increase stroke volume
44
half life of dobutamine
2 minutes
45
is dobutamine pricey
yes
46
adverse effects of dobutamine
- correct hypovolemia before administration - incompatible with bicarbonate -at high doses can cause tachycardia -seizures in cats! use low doses only, if at all
47
dobutamine is sometimes used to
raise blood pressure in anesthetized patients.
48
dobutamine activates what receptors
dopamine, alpha 1, and beta 1 receptors (causing vasoconstriction and increasing intropy)
49
clenbuterol is a
beta 2 agonist
50
can you give clenbuterol to food animals
NO YOU CANNOT !!! DONT DO IT
51
clenbuterol has what effects
-bronchodilator (rarely used now to treat equine asthma) -inhibits uterine tone/contractions (aids in dystocia)
52
clenbuterol is banned in food animals because
used to be used as a growth promotant but residues in meat have caused tachycardia, muscle tremors, and headaches in consumers
53
epinephrine is a
non selective adrenergic agonist
54
epinephrine is used for
emergency treatment of anaphylaxis or for cardiopulmonary resuscitation
55
epinephrine is sometimes added to local anasthetics to
cause vasoconstriction
56
epinephrine increases cardiac output but also
myocardial oxygen consumption
57
you can give epinephrine
IV, IM, SC, IT
58
in anaphylaxis, epinephrine is given for its
vasoconstrictive (alpha 1) and bronchodilator (beta 2) effects and is very useful
59
in CPR situations, epinephrine is indicated when
the animal has a non-shockable rhythm and that only low-dose epinephrine is now recommended
60
prazosin is an
alpha 1 antagonist
61
prazosin has what effects
reduces blood pressure - arterial and venous vasodilatory - sometimes used as adjunctive treatment for heart failure but there are better choices
62
prazosin is no longer recommended for
blocked cats !!!!!!!!
63
why is prazosin no longer used for blocked cats
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
is prazosin protein bound?
yes - 97% protein bound
65
atipamezole is an
alpha 2 antagonist
66
atipamezole is a competitive inhibitor of
alpha 2 receptors
67
atipamezole clinical effects
reverses sedation, cardiovascular effects, and analgesia associated with alpha 2 agonist administration
68
atipamezole is normally administered
IM in small amounts
69
in horses atipamezole is normally given
1/2 IM and 1/2 IV and IV is injected SLOWLY
70
cats are often castrated under an injectible anesthetic combo of dexmed, butorphanol, and ketamine. If reversing this after the procedure, make sure that
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
esmolol is a
beta 1 antagonist
72
esmolol is an ultra short acting IV
beta blocker
73
esmolol is used to treat
supraventricular tachycardias or to test if beta blockers will be effective in controlling arrthymias (esp in cats with HCM) - anesthesia -CPR
74
esmolol is a negative
inotrope and chronotrope
75
esmolol may
decrease myocardial oxygen demand reduces systolic and diastolic blood pressure
76
esmolol adverse effects
hypotension and bradycardia
77
drugs that act similarly to acetylcholine are called
parasympathomimetics / cholinergics / cholinoreceptor stimulants
78
neostigmine is a what
cholinergic
79
neostigmine is a reversible
inhibitor of acetylcholinesterase
80
neostigmine results in
decreased breakdown of Ach at the synaptic cleft and enhanced activity
81
neostigmine is used to increase
gut motility/for its smooth muscle effects and is also used in treatment of myasthenia gravis
82
in myasthenia gravis, autoantibodies attach nicotinic Ach receptors in skeletal muscles. This results in
muscle weakness.
83
by inhibiting acetylcholinesterase, neostigmine causes
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
is neostigmine or pyridostigmine preferred for myasthenia gravis treatment
pyridostigmine because it has a longer duration of action and fewer GI effects
85
atropine and glycopyrrolate are what
anticholinergics
86
atropine and glycopyrrolate are competitive muscarinic antagonists used to
reduce response to parasympathetic nerve impulses
87
effects of atropine and glycopyrrolate are
dose dependent
88
atropine and glycopyrrolate increase
HR and conduction veolcity , inhibit GI smooth muscle contraction, mydriatic, decrease secretions, and bronchodilator
89
glycopyrrolate and atropine are used for
emergency treatment of bradyarrythmias, to facilitate opthalmic exams, such as adjunctive treatment for equine recurrent uveitis
90
adverse effects of atropine and glycopyrrolate
primarily tachycardias at high doses atropine may cause mania can cause ileus, especially in horses
91
glycopyrrolate or atropine - which one crosses BBB more
atropine - so glycopyrrolate has fewer CNS effects
92
the combination of anticholinergics and alpha 2 agonists creates the potential for
myocardial hypoxemia to develop as a result of increased myocardial work
93
N-butylscopolammonium bromide/ hyoscine buytlbromide: is an
anticholinergic
94
N-butylscopolammonium bromide/ hyoscine buytlbromide is only used in
horses but is labelled for cattle in some countries
95
N-butylscopolammonium bromide/ hyoscine buytlbromide has effects similar to
atropine
96
N-butylscopolammonium bromide/ hyoscine buytlbromide is especially useful in horses with
gas/spasmodic colic (relaxes intestine) - but heart rate increases after administration and can't be used to monitor pain for about 30 min
97
N-butylscopolammonium bromide/ hyoscine buytlbromide can be useful for
performing rectal exams in horses and for acute asthma treatment
98
N-butylscopolammonium bromide/ hyoscine buytlbromide common name
buscopan - used to treat spasmodic colic, relax rectum for rectal exams. ad relax esophageal smooth muscle in choked horses
99

Pharmacology (23 decks)

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