GIT Drugs Flashcards

1
Q

What should antiemetic therapy only be considered as?

A

Symptomatic therapy

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2
Q

With vomiting what should be done while providing antiemetic therapy?

A

Determine and resolve underlying disease process

Antiemetic therapy only managing clinical signs

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3
Q

In what three things are antiemetic therapies inappropriate to use?

A

GI infections

  • May prolong infection

GI obstruction

  • Could increase motility resulting in perforation

GI toxicity

  • May prevent patient from eliminating toxin
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4
Q

When would antiemetics be considered with GI toxicity?

A

If animal has eliminated toxin already and vomiting is a secondary response

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5
Q

Where is vomiting coordinated?

A

Vomiting centre in medulla

Various nuclei

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6
Q

What areas feed back to the vomiting centre?

A

Chemoreceptor trigger zone

  • No blood-brain barrier

Peripheral receptors

  • Highest in duodenum but go down to large intestine

Toxins

Vestibular

  • Motion
  • Inner ear infection

Higher CNS

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7
Q

What differs between the different systems that feedback to the vomiting centre?

A

Neurotransmitter - need to know for different antiemetics

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8
Q

On what does the most common antiemetic in small animals act?

A

Nucleus tractus solitarius

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9
Q

What are the more important neurotransmitters in dogs?

A

D2 receptors in chemoreceptor trigger zone

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10
Q

What is apomorphine a more potent emetic agent in and on what does it act?

A

More potent in dogs

Doesn’t work in cats

D2-dopamine receptor agonist

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11
Q

Which neurotransmitters are more important in the cat and what are two drugs that are potent?

A

Alpha2-adrenergic receptors in CRTZ

Xylazine and prochlorperazine

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12
Q

Is histamine a more potent emetic in the dog or cat?

A

Dog

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13
Q

What are the 6 classes of antiemetic drugs?

A

NK1 antagonists

Metoclopramide

Phenothiazines

Antihistamines

5HT3 antagonists

Anticholinergics

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14
Q

What does Maropitant work on?

A

Nucleus tractus solitarius

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15
Q

What is Maropitant an effective antiemetic for in dogs?

A

Acute gastroenteritis

Cytotoxic-induced vomiting

Motion sickness - needs higher dose

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16
Q

Describe how Maropitant acts

A

Selective antagonist of Substance P at the NK1 receptor

Inhibits final common pathway involved in activating the vomiting reflex in CNS

Doesn’t matter about the source of vomiting stimulus

Effective against both peripheral and central stimuli

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17
Q

If vomiting persists with Maropitant use what needs to be determined?

A

The cause of vomiting

Drug only treating symptom not cause

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18
Q

What are the three places Metoclopramide acts?

A

D2 dopaminergic receptors

5HT3-serotonergic receptors

Peripheral pro-cholinergic effect

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19
Q

What is Metoclopramide indicated for?

A

Various emesis-inducing disorders involving central or peripheral activation of vomiting

Cancer chemotherapy

Gastroesophageal reflux

Decreased gastric emptying

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20
Q

How does metoclopramide prevent gastroesophageal reflux?

A

Flushing system empties stomach

Gastroesophageal reflux just doesn’t occur

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21
Q

What is decreased gastric emptying associated with?

A

Inflammatory gastrointestinal disorders

Gastric ulcers

Gastric neoplasia

Autonomic neuropathy (diabetes mellitus)

Pyloric stenosis

Postoperative gastric volvulus patient

Hypokalaemia

Abnormal gastric motility

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22
Q

Which drugs are not registered for animal use in the UK?

A

Phenothiazines

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23
Q

Which receptors do phenothiazines antagonise?

A

Alpha 1 and 2 adrenergic receptors4

D2 dopaminergic receptors

H1 and 2 histaminergic receptors

Muscarinic cholinergic receptors

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24
Q

What are the indications for phenothiazines?

A

Any central or peripheral cause of vomiting

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25
Q

What do antihistamines act upon and what would they be used for?

A

H1 and H2 receptors in the chemoreceptor trigger zone

Used for motion sickness in the dog not the cat

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26
Q

What are 5HT3 antagonists used to control?

A

Cytotoxic drug induced emesis

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27
Q

What are some examples of 5HT3 antagonists?

A

Dolasetron (Anzemet)

Ondansatron (Zofran)

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28
Q

What are anticholinergics effective for?

A

Motion sickness

Antagonism of M1 receptors in vestibular apparatus

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29
Q

What is the major problem associated with anticholinergics?

A

Effect on M2 receptors

Result in potential for delayed gastric emptying and ileus (disruption of normal emptying)

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30
Q

What are 5 anti-ulcer drugs?

A

Nonsystemic antacids

H2 receptor antagonists

Sucralfate

Misoprostol

Omeprazole

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31
Q

Describe non-systemic antacid use

A

Inexpensive drugs

Frequent oral administration - every 4 hours

Treats but doesn’t prevent

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32
Q

What are the three H2 receptor antagonists?

A

Cimetidine

Ranitidine

Famotidine

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33
Q

What are H2-receptor antagonists effective in treating?

A

Gastric ulceration caused by a variety of disorders

  • NSAIDs
  • Uraemia
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34
Q

What should we base our choice of H2 receptor antagonists on?

A

Cost

Client convenience

Concurrent drug therapy

35
Q

What is sulcralfate indicated for?

A

Symptomatic treatment of gastric ulceration

36
Q

What is Misoprostol?

A

Synthetic PGE1

37
Q

What is the main indication for Misoprostol?

A

Management or prevention of NSAID toxicity

38
Q

What does Misoprostol cause and why is it a safety issue?

A

Causes abortion

Issue in relation to who should handle the drug

39
Q

What is Omeprazole?

A

Proton pump inhibitor

40
Q

Describe the use of Omeprazole in small animal veterinary medicine

A

Use is increasingly common but off label

Ulcers or oesophagitis refractory to ther anti-ulcers

Ulcers associated with gastrinomas or mast cell tumours

41
Q

What is Gastroguard (omeprazole) used for?

A

Equine medicine for treatment and prevention of gastric ulcers

42
Q

What do electrolyte solutions enhance?

A

Fluid absorption from the gut

43
Q

What do electrolyte solutions depend on and are linked to?

A

Depend on active absorption of glucose and aminoacetic acid in small intestine

Directly linked with water and sodium movement

44
Q

What are the two types of motility modifying drugs?

A

Opioids

Anticholinergics

45
Q

What do opioids do?

A

Increase segmental contractions in gut (random/multi-directional)

Prolong intestinal transit time

Theoretically allow greater time for fluid to be absorbed

46
Q

What do anticholinergics do within the gut?

A

Decrease peristalsis

47
Q

What can opioids be effective for?

A

Symptomatic treatment

  • Relieve abdominal pain and tenesmus
  • Reduce defecation frequency
48
Q

What are anticholinergics used little in?

A

Management of diarrhoea in dogs and cats

49
Q

What are anticholinergics used in?

A

Management of spasmodic colic in horses

50
Q

Which GIT drugs need to be avoided in cats?

A

Adsorbents

Protectants

51
Q

What are the dose rates of maropitant in dogs for prevention/treatment of emesis due to central/peripheral stimuli?

A

2mg/kg PO daily for up to 5 days

1mg/kg SC daily for up to 5 days

52
Q

What is the dose rate for maropitant in the prevention of motion sickness?

A

8mg/kg PO daily for maximum of two days

53
Q

How does metoclopramide cause increased gastric emptying?

A

Promotes release and increased sensitivity to acetylcholine in smooth muscle

Results in:

  • Increased tone of lower oesophageal sphincter
  • Increased strength of oesophageal contractions
  • Increased gastric antral contractions
  • Relaxation of pylorus
  • Increased smooth muscle contraction in duodenum
54
Q

What are the side effects of metoclopramide?

A

Infrequently cause mental changes

  • Hyperactivity
  • Aggression
  • Depression

May cause gastric spasm and enhance vomiting

55
Q

What are the side effects associated with antihistamines?

A

Drowsiness

Xerostomia (dry mouth)

56
Q

What are the side effects of phenothiazines?

A

Hypotension due to alpha-adrenergic receptor blocking action

57
Q

What shouldn’t anticholinergic drugs be used in?

A

Dogs with parvovirus

58
Q

What could long term use of H2 antagonists cause?

A

Hypoacidity and bacterial overgrowth in the stomach

Not a clinical concern

59
Q

What should be done with H2 antagonists in patients with impaired renal function?

A

Dose should be reduced by 50%

60
Q

What do calcium, magnesium and aluminium containing antacids tend to promote?

A

Calcium

  • Constipation

Magnesium

  • Looser faeces

Aluminium

  • Reduced gastric motility
  • Delay of gastric emtpying
61
Q

What may administration of excessive calcium-containing antacids predispose the patient to?

A

Renal caliculi

62
Q

What are the treatments for vomiting in both chronic and acute cases?

A

Chronic

  • Find underlying causes

Acute

  • Fasting
  • Symptomatic treatment
63
Q

What are the three things that drugs used to treat vomiting tend to affect?

A

Proton-pump inhibitors

Anti-histamines

Anti-cholinergics

64
Q

Describe Sucralfate and what it is used in the treatment of

A

Aluminium hydroxide and sucrose octasulfate

Dissociates in acid

Causes binding to exudate at ulcer sites

Forms a protective barrier and stimulates HCO3, mucus and prostaglandin secretion

Used in treatment of oesophageal and gastric ulceration

65
Q

What are the dose rates of Sucralfate in dogs?

A

<20kg: 0.5mg/dog

>20kg: 1mg/dog

66
Q

What are three HA receptor antagonists used to treat vomiting?

A

Cimetidine

Ranitidine

Famotidine

67
Q

Describe the actions of cimetidine/ranitidine/famotidine

A

Inhibits gastric acid

Some gastric prokinetic activity

Used frequently to treat any sort of regurgitation/vomiting

68
Q

What is a proton pump inhibitor used for treatment of vomiting?

A

Omeprazole

69
Q

Describe the action and use of omeprazole

A

Proton pump inhibitor

Binds parietal cells blocking H+/K+

Inhibits transport of H+ into the stomach

Used for:

  • Gastric hyperacidity
  • GI ulcers
  • Erosions
  • Gastrinomas
70
Q

What is another name for a gastrinoma?

A

Zollinger-Ellison syndrome

71
Q

When should anti-emetic therapy be used?

A

Debilitating vomiting

Animal in pain

Marked fluid/electrolyte loss

72
Q

What is the most appropriate anti-emetic treatment?

A

Management of the underlying disease

Though the cause cannot always be determined in all patients

73
Q

Why might anti-emetic therapy not always be desirable?

A

Vomiting can be protective so may not want to get rid of it

74
Q

Describe the action and use of metoclopramide

A

Para-aminobenzoic acid derivative

Central and GI effect

Antagonises D2-dopaminergic & 5-HT3 receptors

Upper GI prokinetic agent

Can come in tablets, suspension or injection

75
Q

What is a 5-HT3-serotonergic antagonist used for treating vomiting?

A

Ondansetron

76
Q

What is the best anti-emetic for chemotherapy induced nausea and vomiting?

A

Ondansetron

77
Q

What is Ondansetron good for?

A

Chemotherapy-induced nausea and vomiting

Pancreatitis

78
Q

What is a neurokinin-1 receptor antagonist?

A

Maropitant

79
Q

Describe the action and use of Maropitant

A

Neurokinin-1 receptor antagonist

Central and peripheral effects

Stops substance P binding

Very potent!

Useful in any kind of vomiting

80
Q

What is Maropitant licensed for use in and what are the dose rates?

A

Licensed in dogs - soon in cats

Dose is 1mg/kg sub-cutaneous every 24hrs

2mg/kg orally every 24 hours

81
Q

What are some surgical emergencies with small animal abdominal pains?

A

Septic peritonitis

Risk of septic peritonitis

Gastric dilatation and volvulus

Metabolic emergency

Vascular emergency

Pyometra

Dystocia

82
Q

What are the pros and cons of pure opioids ans analgesia?

A

Pros:

  • Very good
  • Reversible
  • Sedation
  • Constant rate infusion

Cons:

  • Sedation
  • Decrease GIT motility
  • Nausea
  • Injectable
83
Q

What are the pros and cons of using partial agonist opioids for analgesia in small animals?

A

Pro:

  • Good analgesia
  • Minimal sedation
  • Less effect on GIT motility
  • Good transmucosal absorption in cats

Cons:

  • Some sedation
  • Can decrease GIT motility
84
Q

What are the pros and cons of using NSAIDs for analgesia in small animals?

A

Pros:

  • Anti-inflammatory
  • No sedation

Cons:

  • Renal toxicity
  • GIT toxicity