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443 - Pharmacology & Toxicology > Adrenergic and Cholinergic > Flashcards

Adrenergic and Cholinergic Flashcards

1
Q

What are the effects of alpha-1 receptors on the cardiovascular system?

A

Vasoconstriction

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2
Q

What are the effects of alpha-2 receptors on the cardiovascular system?

A

Vasoconstriction with presynaptic vasodilation

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3
Q

What are the effects of beta-1 receptors on the cardiovascular system?

A

Increased cardiac output

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4
Q

What are the effects of beta-2 receptors on the cardiovascular system?

A
  • Vasodilation (skeletal muscle and heart)
  • Bronchodilation
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5
Q

What are the three divisions of the ANS?

A
  1. Sympathetic (+adrenal glands)
  2. Parasympathetic
  3. Enteric
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6
Q

What does the ANS control?

A

Involuntary (visceral) functions:
- Smooth muscle
- Cardiac muscle
- Glands

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7
Q

What is the difference in the neuron chains and receptors for the sympathetic and parasympathetic systems?

A

Parasympathetic has a longer pre-ganglionic fiber that synapses in the target tissue, sympathetic has a longer post-ganglionic fiber.

Parasympathetic only uses ACh (pre and post-ganglionic neurons), sympathetic uses NE for post-ganglionic.

Parasympathetic acts on muscarinic receptors, sympathetic acts on adrenergic receptors.

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8
Q

What is released by preganglionic neurons?

A

Acetylcholine

For both sympathetic and parasympathetic systems

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9
Q

Where are nicotinic receptors found?

A

On post-ganglionic fibers.

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10
Q

Where do the preganglionic neurons synapse in sympathetic and parasympathetic systems?

A

S: Synapse in ganglia bilaterally adjacent to the vertebral column.
P: Synapse in target tissue.

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11
Q

What is released by the post-ganglionic neurons in sympathetic and parasympathetic systems?

A

S: NE
P: ACh

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12
Q

What type of receptor is a nicotinic receptor?

A

Ligand-gated ion channels.

Ach is synthesized from acetyl-CoA and choline within the neurons of the ANS and is stored in vesicles ready for release. At the synapse in a sympathetic ganglion, the pre-synaptic neuron is stimulated by an action potential to release acetylcholine into the synapse. This binds to nicotinic receptors on the post-synaptic neuron. Nicotinic receptors are ligand- gated ion channels – their activation allows Na++ influx into the cell causing depolarization.
Ach also binds to pre-synaptic nicotinic receptors, which serves to decrease Ach release.

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13
Q

What enzyme works at the synapse?

A

Acetylcholinesterase (AchE)

Degrades ACh to acetyl-CoA

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14
Q

What type of receptor is an adrenergic receptor?

A

G-protein-coupled receptors

Norepinephrine (NE) is synthesized within the post-ganglionic adrenergic neuron and transported into cytoplasmic vesicles by monoamine transporters. At the synapse at the target tissue, the neuron is stimulated by an action potential to release NE into the
synapse. This binds to adrenergic receptors on the target tissue. Adrenergic receptors are G-protein-coupled receptors – their activation results in signal transduction and the effects of sympathetic stimulation in the target tissue. NE also binds to pre-synaptic sympathetic receptors on the neuron, which serves to decrease NE release (this is especially important for alpha-2 adrenergic receptors).

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15
Q

What are three ways NE can be removed from the synapse?

A
  1. It can be metabolized by post-synaptic catechol-O-methyltransferase (COMT)
  2. It can be transported back into the neuron (by an active norepinephrine transporter) - in the cell it can be recycled or broken down by mitochondrial monoamine oxidase
  3. It can diffuse away from the synaptic cleft and be metabolized in the plasma or in the liver, or excreted in the urine
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16
Q

What type of receptor is a muscarinic receptor?

A

G-protein-coupled receptors

Ach is synthesized from acetyl-CoA and choline within the neurons of the ANS and is stored in vesicles ready for release. At the synapse at the target tissue, the post-ganglionic neuron is stimulated by an action potential to release acetylcholine into the synapse. This binds to muscarinic (M) receptors on the target tissue. Muscarinic receptors are G-protein-coupled receptors – their activation results in signal transduction and the effects of
parasympathetic stimulation in the target tissue. Ach also binds to pre-synaptic muscarinic receptors, which serves to decrease Ach release. Once released, Ach binds to its receptor only briefly; it is rapidly degraded back to acetyl-CoA and choline by acetylcholinesterase (AchE). These Ach components can
then be used within the neuron to resynthesize Ach.

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17
Q

What neurotransmitter can be released systemically from the adrenal glands?

A

Epinephrine and norepinephrine

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18
Q

What are the major products released by the adrenal glands (from superficial to deep)?

A

Mineralocorticoids (eg., aldosterone)
Glucocorticoids (eg., cortisol)
Androgens (eg., dehydroepiandrosterone (DHEA))
Epinephrine and norepinephrine

Salt, sugar, sex, stress effects.

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19
Q

What does the adrenal medulla act like?

A

A specialized sympathetic nervous system ganglion

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20
Q

What type of fibers innervate the adrenal medulla?

A

Preganglionic sympathetic fibers

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21
Q

What substances do chromaffin cells in the adrenal medulla release?

A

Epinephrine (E) and norepinephrine (NE)

Predominately epinephrine

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22
Q

Where does the adrenal medulla release epinephrine and norepinephrine?

A

Into the general circulation

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23
Q

What factors increase the production of epinephrine and norepinephrine?

A

Stress and exercise

Produced in the adrenal medulla.

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24
Q

What is the affinity of epinephrine for adrenergic receptors?

A

High affinity for both alpha and beta adrenergic receptors

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25
Q

What determines the effects of epinephrine on various tissues?

A

The balance of receptor types within the tissue

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26
Q

What are the effects of circulating epinephrine (moderate levels)?

A

Dilation of skeletal muscle, skin, and renal vascular beds; increased cardiac output

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27
Q

What happens to blood pressure with moderate levels of epinephrine?

A

Blood pressure rises moderately

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28
Q

What effect do very high levels of circulating epinephrine have on blood pressure?

A

Predominance of alpha-1 effects on blood vessels, leading to further blood pressure increases

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29
Q

How does norepinephrine differ in its affinity compared to epinephrine?

A

Norepinephrine has a stronger affinity for alpha receptors than beta receptors

Epinephrine has a high affinity for both.

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30
Q

Where do sympathetic and parasympathetic neurons originate?

A

S: Originate in the spinal cord (T1 – L3)
P: Originate in the brainstem and sacrum.

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31
Q

What are the target tissues of the SNS?

A
  • Eye
  • Salivary glands
  • Arterioles
  • Lungs
  • Heart
  • Stomach
  • GIT
  • Kidney
  • Bladder
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32
Q

What are the target tissues of the PNS?

A
  • Eye + lacrimal gland
  • Salivary gland
  • Lungs
  • Heart
  • GIT
  • Bladder
  • Penis and prostate

*Remember that the PSNS does not directly affect vascular smooth muscle

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33
Q

What type of innervation does the heart have? What type of innervation do blood vessels have?

A

The heart has both parasympathetic and sympathetic innervation, while the blood vessels have only sympathetic innervation.

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34
Q

What is the effect of M2 receptors on the cardiovascular system?

A

Decreased cardiac output.

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35
Q

What does sympathetic tone refer to?

A

The frequency of release of neurotransmitters from the nerve

It indicates how often neurotransmitters are discharged in the sympathetic nervous system.

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36
Q

What is the effect of decreased sympathetic tone on blood vessels?

A

Vasodilation occurs due to relaxation of vascular smooth muscle

This is because decreased sympathetic tone leads to less contraction of the smooth muscle.

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37
Q

What is the relationship between sympathetic tone and arteriolar diameter?

A

Increased sympathetic nerve discharge leads to decreased arteriolar diameter (vasoconstriction).

Decreased sympathetic tone reduces smooth muscle contraction and allows arteriolar dilation.

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38
Q

At baseline, what effect does tonic sympathetic stimulation have on arterioles?

A

Keeps arterioles partially constricted

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39
Q

What occurs when sympathetic tone increases?

A

Arterioles vasoconstrict

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40
Q

What type of receptors are on blood vessel smooth muscle?

A

Alpha 1 and 2 receptors.

But mostly alpha 1.

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41
Q

Receptor stimulation on blood vessels will have what effect?

A

Stimulation of either receptor type (alpha 1 or 2) on the blood vessel will induce vasoconstriction.

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42
Q

What are the effects of parasympathetic overstimulation?

A

Acronym DUMBBELLS:
* Diarrhea
* Urination
* Miosis
* Bronchorrhea (watery discharge from lungs)
* Bradycardia
* Emesis
* Lacrimation
* (Lethargy)
* Salivation/sweating

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43
Q

What is horner’s syndrome?

A

Loss of sympathetic supply to the head and neck resulting in miosis, enophthalmos, and prolapsed third eyelid.

Clinical signs:
- constricted pupil (miosis) on the affected side
- sinking of affected eyeball back into socket (enophthalmia) due to loss of innervation of muscle maintaining tone in orbit
- passive protrusion of the third eyelid across the affected eye due to loss of innervation to tonic smooth muscle responsible for keeping the eyeball pushed forward in its socket.
- drooping (ptosis) of upper lid on affected side due to loss of innervation of smooth muscle in lid
- denervation of sweat glands on affected side causes profuse sweating

Horner’s syndrome is basically the inability to do what the body does in a life-threatening situation - pupils dilate, eyes widen in fright and bulge in their sockets, and profuse sweating

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44
Q

What is the term for drugs that act similarly to endogenous catecholamines?

A

sympathomimetics / adrenergic agonists

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45
Q

What are sympathomimetics?

A

Drugs that act similarly to endogenous catecholamines

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46
Q

What drugs are alpha 2 agonists?

A
  • Xylazine
  • Detomidine
  • Dexmedetomidine
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47
Q

What drugs are beta 1 agonists?

A

Dobutamine

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48
Q

What drugs are beta 2 agonists?

A

Clenbuterol

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49
Q

What drugs are alpha 1 antagonists?

A
  • Prazosin
  • Acepromazine
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50
Q

What drugs are alpha 2 antagonists?

A

Atipamezole

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51
Q

What drugs are beta 1 antagonists?

A

Esmolol

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52
Q

What drugs are non-selective adrenergic agonists?

A
  • Epinephrine
  • Ephedrine
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53
Q

What is the function of alpha 2 agonists?

A

Alpha 2 agonists are sedatives and analgesics that decrease cardiac output

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54
Q

When should alpha 2 agonists be used? When should they not?

A
  • Good premeds for anesthesia
  • Good for standing procedures
  • Bad in patients with compromised CV function
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55
Q

Does reducing the dose of alpha 2 agonists change the adverse effects?

A

Reducing the dose does not reduce the magnitude of the adverse effects on cardiac output, but does reduce the duration of these effects.

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56
Q

How do alpha 2 agonists provide sedation and analgesia?

A
  • Sedation due to inhibition of NE release in the brainstem
  • Analgesia due to reduced neurotransmitter release and signal transmission in afferent pathways
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57
Q

How do alpha 2 agonists reduce cardiac output?

A

Initial vasoconstriction leads to reflex bradycardia.

When an alpha-2 agonist is administered, it initially causes vasoconstriction, leading to an increase in blood pressure. This increase is sensed by baroreceptors in the carotid sinus and aortic arch, which trigger a compensatory response. The baroreceptors activate the parasympathetic nervous system and inhibit sympathetic activity. However, because the alpha-2 agonist reduces sympathetic tone (by inhibiting norepinephrine release), it results in bradycardia. The combination of increased parasympathetic tone and decreased sympathetic tone leads to a lower heart rate and reduced cardiac output, even though the initial vasoconstriction raised blood pressure.

So, the bradycardia is a result of the baroreceptor reflex trying to compensate for the initial vasoconstriction caused by the alpha-2 agonist.

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58
Q
A
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59
Q

What type of drug is xylazine?

A

Alpha 2 agonist

Xylazine is primarily used as a sedative.

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60
Q

In which species is xylazine commonly used?

A

Horses and ruminants

Ruminants require approximately 1/10th the dose of horses for the same effect.

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61
Q

What are common side effects of xylazine?

A
  • AV block
  • Reduced GI motility
  • Sweating
  • Increased myometrial tone
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62
Q

What should be considered when using xylazine in late pregnant animals?

A

Increased risk of premature delivery

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63
Q

What is a recommended combination for better sedation and pain control with xylazine?

A

Butorphanol

Butorphanol is an opioid that enhances the effects of xylazine.

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64
Q

How can xylazine be reversed?

A

Yohimbine or atipamezole

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65
Q

List the alpha 2 agonists commonly used in large animals in order of cardiovascular effects intensity.

A
  • Xylazine
  • Detomidine
  • Romifidine
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66
Q

What is the serum half-life of xylazine in horses?

A

About 50 minutes

Full recovery from sedation usually occurs within 2-3 hours.

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67
Q

How does the sedation from detomidine compare to that of xylazine?

A

Detomidine provides deeper and more reliable sedation. However, cardiovascular effects are more prominant with detomidine.

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68
Q

Why might romifidine be preferred for certain procedures?

A

It causes less ataxia

Important for procedures like standing MRI where stability is crucial.

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69
Q

Do the analgesic effects or the sedative effects of alpha 2 agonists last longer?

A

Sedative effects last longer, analgesic effects do not last as long.

This is a common characteristic of all alpha 2 agonist drugs.

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70
Q

What effect do alpha 2 agonists tend to have on urine production?

A

Diuretic effect

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71
Q

What type of drug is detomidine?

A

Alpha 2 agonist

Detomidine is primarily used for sedation and pain control.

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72
Q

How much more potent is detomidine compared to xylazine?

A

50-100 times more potent

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73
Q

What is the usual dosing measurement for detomidine?

A

Micrograms

It is important not to confuse this with milligrams.

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74
Q

In which animal is detomidine primarily used?

A

Horses

It can also be used in cattle.

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75
Q

What is one of the primary benefits of using detomidine?

A

Provides better sedation and pain control for standing surgery

76
Q

True or False: Detomidine is likely to cause premature delivery in pregnant animals.

A

False

Detomidine may be less likely to cause premature delivery compared to other sedatives.

77
Q

What can be used to reverse the effects of detomidine?

A

Alpha 2 antagonist (atipamezole)

78
Q

What is dexmedetomidine?

A

An alpha 2 agonist used commonly in small animal medicine for sedation

Similar to medetomidine, it is often used for procedures requiring sedation.

79
Q

How is dexmedetomidine dosed?

A

Based on body surface area

80
Q

What effect does dexmedetomidine have when used as an anesthetic premed?

A

Reduces maintenance anesthetic needs

This can lead to lower overall anesthetic drug consumption.

81
Q

What is the reversal agent for dexmedetomidine?

A

Atipamezole

82
Q

What drug can be used to induce emesis in cats?

A

Dexmedetomidine, causes over 50% of cats to vomit.

83
Q

What is medetomidine a mixture of?

A

Dexmedetomidine and levomedetomidine

Medetomidine contains both enantiomers, while dexmedetomidine consists only of the dex- enantiomer. This means medetomidine requires double the dose of dexmedetomidine since half of the enantiomers are inactive.

84
Q

How does the potency of dexmedetomidine compare to medetomidine?

A

Dexmedetomidine is more potent

85
Q

Is dexmedetomidine labeled for use in horses and cattle?

A

No

Although it has been studied in these species, it is not labeled for use and other alpha 2 agonists should be utilized.

86
Q

What should be used in large animal species instead of dexmedetomidine?

A

Appropriately labeled products like xylazine or detomidine

87
Q

What are the most concerning side effects of alpha 2 agonists?

A

Cardiovascular effects - decreased cardiac output

88
Q

What effect do alpha 2 agonists have on the cardiovascular system?

A

They will decrease cardiac output

89
Q

In which type of animals are alpha 2 agonists best used?

A

Healthy animals - NO for animals with CV disease or shock

90
Q

Should alpha 2 agonists be used in animals with cardiovascular disease or in shock?

A

No

91
Q

What is the relationship between analgesia and sedation in alpha 2 agonists?

A

Good analgesia but shorter than the sedative effect

This means pain relief may not last as long as sedation.

92
Q

How does the efficacy of alpha 2 agonists improve when combined with opioids?

A

Better sedation and analgesia

The combination enhances the overall effectiveness of treatment.

93
Q

What type of agonist is dobutamine?

A

Beta 1 agonist

94
Q

What is the primary effect of dobutamine?

A

Positive inotrope that does not increase heart rate at normal doses

It enhances the force of heart contractions without significantly affecting heart rate.

95
Q

What is the half-life of dobutamine?

A

2 minutes

This short half-life necessitates continuous rate infusion (CRI) for effective use.

96
Q

What must be corrected before administering dobutamine?

A

Hypovolemia

97
Q

What is incompatible with dobutamine?

A

Incompatible with bicarbonate

Mixing these can lead to adverse reactions.

98
Q

What adverse effect can occur at high doses of dobutamine?

A

Tachycardia

99
Q

What unique adverse effect can dobutamine cause in cats?

A

Seizures!!!!

Only use low doses in cats if it is used at all.

100
Q

What receptors does dopamine activate?

A

Dopamine, alpha 1, and beta 1 receptors

This leads to both vasoconstriction and increased cardiac contractility.

101
Q

What is the effect of dopamine at typical doses?

A

Renal vasodilation

This effect may provide renal protection during hypotensive events.

102
Q

What can happen at very high doses of dopamine?

A

Renal vasoconstriction

High doses can counteract the protective effects on the kidneys.

103
Q

What are the physiological effects of dopamine?

A

Positive inotrope and diuretic

It increases heart contractility and promotes urine production.

104
Q

Dobutamine should be given as …

A

a continuous rate infusion (CRI)

Due to its short half-life, continuous administration is necessary.

105
Q

What is clenbuterol?

A

A beta 2 agonist

106
Q

What is a primary use of clenbuterol?

A

Bronchodilator

107
Q

What are current recommended treatments for equine asthma?

A
  • Steroids
  • Albuterol
  • Ciclesonide

Clenbuterol is now rarely used

108
Q

What effect does clenbuterol have on uterine tone?

A

Inhibits uterine tone/contractions

109
Q

In what situation can clenbuterol be used as an aid?

A

During dystocia

110
Q

What beta 2 agonist cannot be used in food animals?

A

Clenbuterol

111
Q

What was clenbuterol formerly used as in food animals?

A

A growth promotant

112
Q

What health issues have been caused by clenbuterol residues in meat?

A
  • Tachycardia
  • Muscle tremors
  • Headaches
113
Q

What is the primary classification of epinephrine?

A

Non-selective adrenergic agonist

114
Q

What are the emergency uses of epinephrine?

A

For anaphylaxis or cardiopulmonary resuscitation

115
Q

How is epinephrine sometimes used in local anesthetics?

A

To cause vasoconstriction

116
Q

What effect does epinephrine have on cardiac output?

A

Increases cardiac output but also myocardial oxygen consumption

117
Q

What is a potential drawback of increasing cardiac output with epinephrine?

A

Increased myocardial oxygen consumption

118
Q

What are the routes of administration for epinephrine?

A

IV, IM, SC, IT

119
Q

During cardiopulmonary resuscitation, what is the primary effect of epinephrine?

A

Increase arterial blood pressure (alpha 1 effect) and coronary perfusion

120
Q

Is the use of epinephrine associated with increased long-term survival during cardiac arrest?

A

No, it is not associated with increased long-term survival. It is instead associated with return of pulse.

121
Q

What recent update was made to CPR guidelines regarding epinephrine use?

A

Low-dose epinephrine is now recommended when a non-shockable rhythm is present

122
Q

What was the previous recommendation for epinephrine dosage if low-dose failed?

A

High dose of epinephrine

Now only a low dose is recommended

123
Q

What effects of epinephrine are useful in treating anaphylaxis?

A

Vasoconstrictive (alpha 1) and bronchodilatory (beta 2) effects

124
Q

What is prazosin?

A

An alpha 1 antagonist

125
Q

What effect does prazosin have on blood pressure?

A

Reduces blood pressure through arterial and venous vasodilation

126
Q

What is a potential use of prazosin in heart treatment?

A

Sometimes used as adjunctive treatment for heart failure but better options are available

127
Q

What condition is prazosin used to treat related to the urinary tract?

A

Functional urethral obstruction

128
Q

What was prazosin previously thought to be useful for in cats?

A

Treatment of blocked cats

No longer recommended!!

129
Q

How is prazosin used after unblocking in cats?

A

Given for several weeks to decrease urethral spasms

Recently shown to increase chance of reblocking!!

130
Q

What recent evidence has emerged regarding prazosin and cats?

A

May INCREASE risk of reblocking

131
Q

What is the protein binding percentage of prazosin?

A

Approximately 97% protein bound

132
Q

What type of receptor does atipamezole act on?

A

Alpha 2 antagonist

Atipamezole is specifically a competitive inhibitor of alpha 2 receptors.

133
Q

What effects does atipamezole reverse?

A

Sedation, cardiovascular effects, and analgesia from alpha 2 agonists

134
Q

How is atipamezole usually administered in small animals?

A

Intramuscularly (IM)

135
Q

What is the administration method for atipamezole in horses?

A

½ IM and ½ IV, injected slowly if IV

136
Q

What injectable anesthetic combination is often used for cat castration?

A

Dexmedetomidine, butorphanol, and ketamine

137
Q

Atipamezole is a competitive inhibitor of _______ receptors.

A

alpha 2

138
Q

What should be considered when reversing an alpha 2 agonist with atipamezole?

A

Alternative pain control

This is necessary due to the reversal of analgesic effects.

139
Q

What type of drug is esmolol?

A

Beta 1 antagonist

140
Q

What is the duration of action of esmolol?

A

Very short acting

141
Q

What conditions is esmolol used to treat?

A

Supraventricular tachycardias

It is also used to test the effectiveness of beta blockers for arrhythmias.

142
Q

What are the effects of esmolol on the heart?

A
  • Negative inotrope
  • Negative chronotrope

These effects may lead to a decrease in myocardial oxygen demand.

143
Q

How does esmolol affect blood pressure?

A

Reduces systolic and diastolic blood pressure

144
Q

What are common adverse effects of esmolol?

A
  • Hypotension
  • Bradycardia
145
Q

Drugs that act similarly to acetylcholine are called…

A

parasympathomimetics/cholinergics/ cholinoreceptor stimulants.

146
Q

What are parasympathomimetics?

A

Drugs that act similarly to acetylcholine

147
Q

What drugs are cholinergics?

A

Neostigmine

148
Q

What drugs are anticholinergics?

A
  • Atropine
  • Glycopyrrolate
  • N-Butylscopolammonium bromide/Hyoscine butylbromide
149
Q

What type of inhibitor is neostigmine?

A

Cholinergic - A reversible inhibitor of acetylcholinesterase

Neostigmine increases the availability of acetylcholine by preventing its breakdown.

150
Q

What is the primary effect of neostigmine on acetylcholine at the synaptic cleft?

A

Decreased breakdown of Ach and enhanced activity

151
Q

What are the therapeutic uses of neostigmine?

A

Increase gut motility, for its effects on smooth muscle, and treatment of myasthenia gravis

Neostigmine’s smooth muscle effects are utilized in gastrointestinal conditions.

152
Q

What condition results from autoantibodies attacking nicotinic Ach receptors?

A

Myasthenia gravis

This condition leads to muscle weakness due to reduced receptor availability.

153
Q

How does neostigmine help in the treatment of myasthenia gravis?

A

By increasing the availability of acetylcholine

This enhances interaction with the remaining nicotinic receptors.

154
Q

Which drug is preferred over neostigmine for treating myasthenia gravis and why?

A

Pyridostigmine; it has a longer duration of action and fewer GI effects

155
Q

True or False: Organophosphates are reversible acetylcholinesterase inhibitors.

A

False

Organophosphates, including sarin, are irreversible inhibitors.

156
Q

Fill in the blank: Neostigmine is used to increase _______ in the gut.

A

motility

Neostigmine’s effects on smooth muscle enhance digestion.

157
Q

What are atropine and glycopyrrolate classified as?

A

Anticholinergics

They are competitive muscarinic antagonists.

158
Q

How do atropine and glycopyrrolate affect parasympathetic nerve impulses?

A

They reduce response to parasympathetic nerve impulses.

They act as anticholinergics by competitively binding to muscarinic receptors, resulting in an antagonistic effect.

159
Q

What is the effect of atropine and glycopyrrolate on heart rate?

A

They increase heart rate and conduction velocity by reducing the parasympathetic nerve impulses.

160
Q

What effect do atropine and glycopyrrolate have on gastrointestinal smooth muscle?

A

They inhibit GI smooth muscle contraction.

161
Q

What is a mydriatic effect? What drugs cause it?

A

Dilates pupil. Effect of atropine and glycopyrrolate.

162
Q

What bodily secretions are decreased by atropine and glycopyrrolate?

A

Saliva and airway secretions.

163
Q

Name one emergency treatment use for atropine and glycopyrrolate.

A

Treatment of bradyarrhythmias.

164
Q

In addition to treating bradyarrhythmias, what is another use for these drugs?

A

Facilitate ophthalmic exams.

165
Q

What condition can glycopyrrolate help prevent in equine recurrent uveitis?

A

Prevent synechiae from forming.

166
Q

What is one application of atropine and glycopyrrolate as a bronchodilator?

A

Acute RAO treatment.

167
Q

What was a historical use of atropine and glycopyrrolate in veterinary medicine?

A

Anesthetic premed to reduce secretions and maintain heart rate.

168
Q

What is the primary adverse effect of atropine and glycopyrrolate?

A

Tachyarrhythmias.

169
Q

What can high doses of atropine cause?

A

Mania.

170
Q

What gastrointestinal issue can atropine and glycopyrrolate cause, especially in horses?

A

Ileus.

171
Q

Which drug (atropine or glycopyrrolate) does not cross the blood-brain barrier to the same extent?

A

Glycopyrrolate, as a result has less CNS effects compared to atropine

172
Q

What should the use of anticholinergics be based on?

A

Individual patient risk factors and monitored parameters.

173
Q

True or False: The combination of anticholinergics and alpha-2 agonists is without risk.

A

False.

174
Q

What potential risk does the combination of anticholinergics and alpha-2 agonists create?

A

Myocardial hypoxemia.

175
Q

Fill in the blank: Anticholinergics are used to treat ______ during anesthesia.

A

Bradycardia.

BUT should not be given as premed together with alpha 2 agonists

176
Q

What are the effects of atropine and glycopyrrolate?

A
  • Increase HR and conduction velocity
  • Inhibit GI smooth muscle contraction
  • Mydriatic (dilates pupil)
  • Decrease secretions (saliva, airway…)
  • Bronchodilator
177
Q

What are glycopyrrolate and atropine mainly used for?

A

Used for emergency treatment of
bradyarrhythmias or to facilitate ophthalmic exams

178
Q

What is N-butylscopolammonium bromide commonly known as?

A

Buscopan

179
Q

What type of drug is N-butylscopolammonium bromide?

A

Anticholinergic

180
Q

In which species is N-butylscopolammonium bromide primarily used?

A

Horses

It is also labeled for cattle in some countries.

181
Q

What are the effects of N-butylscopolammonium bromide similar to?

A

Atropine

Both drugs have similar anticholinergic effects.

182
Q

What condition is N-butylscopolammonium bromide especially useful for in horses?

A

Gas/spasmodic colic

It helps to relax the intestine.

183
Q

What happens to heart rate after administering N-butylscopolammonium bromide?

A

Heart rate increases

This increase can hinder the monitoring of pain for approximately 30 minutes.

184
Q

What procedures can N-butylscopolammonium bromide assist with in horses?

A
  • Performing rectal exams
  • Treating acute equine asthma

It helps relax the rectum and esophageal smooth muscle.

185
Q

What part of the esophagus does N-butylscopolammonium bromide relax in choked horses?

A

Distal part

This helps alleviate choke in horses.

443 - Pharmacology & Toxicology (9 decks)

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