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Intro to Pharmacology > Week 6 - Antiemetics > Flashcards

Week 6 - Antiemetics Flashcards

1
Q

Emesis is defined as the action or process of _______ OR the reflex act of _____ the contents of the _____ through the ______.

A

vomiting, ejecting, stomach, mouth

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2
Q

What are some of the common causes of Emesis?

A
  • Ingestion of toxins:
     Poisonous plants
     Spoiled cat/dog food
     Various human medication
     Pieces of string or yarn (cats)
     Certain human foods
  • Certain medications, cancer chemotherapy and radiation
  • Intense pain
  • Emotional stress (such as fear)
  • A reaction to certain smells or odors
  • Early stages of pregnancy (not enough data in animals)
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3
Q

What are locally acting emetics?

A

Locally acting emetic cause gastric irritation

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4
Q

What are central acting emetics?

A

No BBB so drugs can enter and act faster here

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5
Q

What are the triggers and centers of emesis?

A
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6
Q

Nausea and vomiting may be manifestations of many conditions and may occur due
to stimulation of emesis vomiting center (VC) that responds to inputs from:

A
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7
Q

What parts of the brain are involved in emesis?

A

Vomiting enter is located in the medulla oblongata.
Receptors listed under each
What connects with vomiting center?

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8
Q

What are the main NTs and their receptors involved in the pathophysiology of N&V?

A

Receptors in green

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9
Q

When is therapeutic emesis used?

A

In prevention of clinical signs in dogs and cats who have had oral exposure to toxins,
medications, plant hazards, people food (apple seeds, apricot seeds, alcohol, coffee, chocolate).

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10
Q

What are some examples of therapeutic emetics used on dogs?

A

 Apomorphine
 Hydrogen peroxide

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11
Q

What are some examples of therapeutic emetics used on cats?

A

 Xylazine
 Medetomidine/dexmedetomidine
 Midazolam/Hydromorphone combination

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12
Q

Receptors in CTZ
Dogs
* Increase ____ receptors compared to cats — stimulation
of emesis is more ______
* Increased ___ receptors — _____ is a more potent emetic agent in dogs

A

D2, successful, H1, histamine

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13
Q

Receptors in CTZ
Cats
Decreased ___ receptors … _______ ______ as anti-emetic drugs are less successful in cats
* Increased sensitivity to ___ -receptors… greater emesis production by certain ___-________

A

D2, Dopamine, antagonists, α2, α2, stimulants

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14
Q

What does this mean?

A

Dogs and cats respond differently to emetic and anti-emetic drugs

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15
Q

What is Apomorphine’s MOA?

A

a non-selective Dopamine Agonist (activates D2 and D1

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16
Q

What is a brand name of Apo?

A

Apokyn^R

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17
Q

Because dogs have more ______ receptors, they are more likely
to _____ when given apomorphine

A

dopamine, vomit

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18
Q

What are the therapeutic uses of Apomorphine?

A

 Can be given orally (slow action)
 Rapid onset when injected
 The ability to reverse
 Dose: 0.02 -0.04 mg/kg , IV or IM

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19
Q

Because dogs have more ______ receptors, they are more likely
to _____ when given apomorphine

A

dopamine, vomit

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20
Q

Because cats have less ___ receptors, they are less likely to vomit when given apomorphine.

A

D2

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21
Q

Apomorphine act directly on the ____

A

CTZ

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22
Q

Contrary to its name, apomorphine does not bind
to ______ receptors. However, it has some ____-like effects. ______ have repressive effects on the CNS, such as?

A

opioid, opioid, Opioids
* Cause sedation
* Cardiac and respiratory depression
* Suppression of the emetic (vomiting) center

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23
Q

Apomorphine causes?

A

Emesis and it can also suppress emesis.

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24
Q

Apomorphine’s effect depends on ? Provide examples.

A

which center in the brain is reached faster.
* If it reached the CTZ first, we get emesis
 IV injection of apomorphine will reach the CTZ in the blood and emesis will start immediately
 Crossing BBB takes longer for the drug: by the time it has its suppressing effect…. Its good!
Apomorphine
* If its opioid properties reach the Emesis Center first, it will shut it down and prevent emesis

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25
Q

What is important about administering Apomorphine?

A

The route of administration is important.

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26
Q

When administering apomorphine, __ or ______ (___) is best to win the race to the CTZ.

A

IV, transmucosal, Clevor

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27
Q

Transmucosal administration and Apo:
Highly dissolvable tablet into conjunctiva and eye ball
Easy absorption into mucosal
Can be irritation to sclera
Now you have to fish out the tablet back

A
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28
Q

Can you reverse Apomorphine? If so, explain how.

A

Too much sedation?
Can reverse with an opioid antagonist such as Naloxone
So, this is reversal of CNS effects - Not reversal of emesis
Too much emesis?
Can reverse with a dopaminergic antagonist such as Acepromazine (ACE)

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29
Q

Emesis in cats
Cats like ___-____ drugs such as ?

A

α2 -agonist
xylazine & medetomidine/dexmedetomidine

30
Q

Alpha-agonist drugs are
* Highly ______, directly stimulate receptors in the brain and __
* Stimulate ___ -receptors in ____ and ____ center
* Dose: ?
* Vomiting within ____

A

lipophilic, GI, α2, CTZ, emetic

0.4-0.5 mg/kg, IV or IM

minutes

31
Q

Which emetics are most successful in cats? Explain why.

A

α2- antagonists: Yohimbine (xylazine)
Atipamezole (medetomidine)
* Best option for cats
* Commonly used
* Not reliable in dogs
* Use lower doses than are used for sedation

32
Q

What do you have to be mindful of when adminstering antiemetics?

A

vomiting is a protective mechanisms, only use anti-emetics when
vomiting become a deterrent to patient’s health and recovery
 Mask signs of disease / improvement
 Toxin ingestion: may allow it to remain in GI tract

33
Q
A
34
Q

What is the MOA of Ondansetron and Graniestron?

A

Block 5-HT3 receptor in VC and CTZ

35
Q

What are the routes of administration commonly used for Ondansetron and Graniestron?

A

Orally or i.p

36
Q

In what situations would you use Ondansetron or Graniestron?

A

Chemotherapy induced nausea and vomiting (cisplatin)
Post-radiation and post-operative nausea and vomiting
Effects are increased by combination with corticosteroids and NK1 antagonists

37
Q

What are the adverse effects of Ondansetron and Granisetron?

A

(well tolerated)
Mild headache
Dizziness
Itching
Constipation/diarrhea
Minor ECG abnormalities

38
Q

Ondanstron and Graniestron are ?

A

Serotonin 5-HT3 Antagonists

39
Q

What are the two types of Dopamine D2 Antagonists?

A

Prokinetic drugs
Neuroleptics (antipsychotics)

40
Q

Give two examples of Dopamine - prokinetic drugs

A

 Metoclopramide (ReglanR)
 Domperidone

41
Q

Give two examples of Dopamine - neuroleptics (antipsychotics)

A

 Chlorpromazine
 Droperidol

42
Q

What is the MOA of Dopamine D2 Antagonists?

A

Block D2 receptors and serotonin receptors in CTZ

43
Q

What are Dopamine D2 Antagonists typically used for?

A

Most commonly used for NV of non-specific causes
Drug response, post-operative

44
Q

What are the adverse effects of Dopamine D2 Antagonists?

A

Dyskinesia
Sedation
Postural hypotension
Extrapyramidal symptoms: tremor, rigidity

45
Q

List two examples of Substance P Antagonists?

A
  • Aprepitant (PO)
  • Cerenia (PO; SC; IV), 2 hr before travel (pain management)
46
Q

What is the MOA of Substance P Antagonists?

A

Competitively binds to the neurokinin1 (NK1) receptor
in VC and other areas

47
Q

What are Substance P Antagonists used for?

A

To treat motion sickness
In prevention of acute and delayed chemotherapy-induced NV
Post-operative NV (less often)
Usually combined with 5-HT3 antagonists and corticosteroids

48
Q

What are the adverse effects of Substance P Antagonists?

A

Dyskinesia
Sedation
Dizziness
Hiccups
Hypotension

49
Q

Name two examples of Antihistamines: H1 Antagonists

A

 Diphenhydramine (Benadryl R )
 Dimenhydrinate (Gravol R

50
Q

What is the MOA of Antihistamines: H1 Antagonists

A

Block histamine at H1 receptor (dogs have lot of H1 receptors)
Block Ach at muscarinic M1 receptor

51
Q

What are Antihistamines: H1 Antagonists typically used for?

A

Effective for motion sickness (some benefit for dogs, poor response in cats)
morning sickness in pregnancy

52
Q

What are the adverse effects of Antihistamines: H1 Antagonists?

A

Prominent sedation, hypotension, confusion
Anticholinergic effects (dry mouth, dilated pupils, urinary retention, constipation)

53
Q

List two examples of Anticholinergics: Muscarinic Receptor Antagonists

A

 Hyoscine Butylbromide (Hysomide R )
 Dicyclomine

54
Q

What is the MOA of Anticholinergics: Muscarinic Receptor Antagonists

A

Block Ach at the muscarinic M1 receptor

55
Q

What is the route of administration typically used for Anticholinergics: Muscarinic Receptor Antagonists?

A

Orally, injections, patches

56
Q

What is the route of administration typically used for Anticholinergics: Muscarinic Receptor Antagonists?

A

Orally, injections, patches

57
Q

What are Anticholinergics: Muscarinic Receptor Antagonists typically used for?

A

In motion sickness (transdermal patches behind the ear)
Morning sickness (dicyclomide)
Not in chemotherapy-induced NV

58
Q

What are the adverse effects of Anticholinergics: Muscarinic Receptor Antagonists

A

Tachycardia
Blurred vision
Dry mouth
Constipation
Urinary retention (atropine-like actions)

59
Q

List some examples of Benzodiazepines?

A

 Lorazepam (PO, IV)
 Diazepam (PO, IV, PR)
 Midazolam (PO, IV, PR, Intranasal, SL)

60
Q

What is the MOA of BDZ’s?

A

Enhance effects of GABA by binding to receptors in the brain

61
Q

What are BDZ’s used for?

A

Psychotropic medication
Calming effect on the brain (GABAA –mediated)
Anticipatory nausea and vomiting (chemotherapy – induced )

62
Q

What are the adverse effects of BDZ’s?

A

Sedation
Dry mouth
Dizziness
Paradoxical agitatio

63
Q

List some examples of corticosteroids?

A

 Dexamethasone
 Methylprednisolone

64
Q

What is the MOA of Corticosteroids?

A

Not well understood (anti-inflammatory effects)

65
Q

What are Corticosteroids used for?

A

In chemotherapy-induced vomiting
Combined with 5-HT3 antagonists or NK1 receptor antagonists

66
Q

What are the adverse effects of corticosteroids?

A

Hyperglycemia
Hypertension
Osteoporosis
Insomnia
increased intraocular pressure,
Increased susceptibility to infection
increased appetite & obesity

67
Q

List some examples of Cannabinoids

A

 Nabilone
 Dronabinol

68
Q

What is the MOA of Cannabinoids?

A

not understood, act at CB1 receptors in VC

69
Q

What are cannabinoids used for?

A

Not commonly
Anticancer drug-induced vomiting

70
Q

What are the adverse effects of cannabinoids?

A

Euphoria
Dysphoria
Sedation
Agitation
Hallucination
Withdrawal syndrome:
Restless
Insomnia
Irritability
Autonomic effects:
Tachycardia
Palpitation

71
Q
A

Intro to Pharmacology (31 decks)

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