Lecture 17/18 - GI medications Flashcards

1
Q

What is responsible for protecting the stomach from acidic conditions?

A

Bicarbonate + Mucous

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2
Q

When do ulcers occur, most basic mechanism?

A

Acid > Protective layer

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3
Q

What can cause ulcers?

A
Drugs = NSAIDs + Corticosteroids 
H.pylori 
Mast cell tumors 
GI diseases 
Long interavals of no food in horses
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4
Q

What is the most basic mechaism by which ulcers are healed?

A

decrease acid

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5
Q

What are common signs of ulcers in dogs?

A

Vomiting +/- blood
Weight loss + Anaemia
Black tarry stool

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6
Q

What are common signs of ulcers in cats?

A

Vomiting +/- blood
Anemia + Weight loss + loss of appetite
Abdominal pain
Tarry stool

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7
Q

What is EGUS?

A

Equine gastric ulcer syndrome

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8
Q

What type of horse is most prone to ulcerations?

A

Racing horses (~60%)

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9
Q

What is the most basic mechanism by which horses get ulcers?

A

Always producing acid, so must be able to eat at all times to prevent erosion of stomach lining

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10
Q

What are signs that a horse may have a stomach ulceration?

A

Poor appetite + Lethargy + Weight loss + Poor performance + Attitude

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11
Q

What are the two parts of a horses stomach?

A

Non-glandular + Glandular

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12
Q

What is ESGUS?

A

Non-glandular

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13
Q

What is EGGUS?

A

Glandular

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14
Q

What portion of the stomach is most prone to ulcerations?

A

Non-glandular

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15
Q

What is an important mechanism by which H+ is taken into the parietal cell?

A

Histamine from ECL cell stimulates H2

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16
Q

What is the important protective portion of the molecular cascade of parietal cells?

A

PGE2 + PGI2 –> stimulates EP3

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17
Q

What does EP3 do? (two different cells)

A

Superficial epi cell = mucous + bicarb

Parietal cell = prevents H+ secretion

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18
Q

What inhibits PG’s?

A

NSAIDs

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19
Q

What do antacids block?

A

H+ directly

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20
Q

What do proton pump inhibitors inhibit?

A

H/K ATPase

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21
Q

What is the pH at the mucous layer?

A

7

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22
Q

What is the pH in the gastric lumen?

A

2

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23
Q

What does Mg do in the stomach?

A

Binds H+
Not absorbed
Also acts as a laxative

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24
Q

What does Al do in the stomach?

A

Binds H+
Not absorbed
Causes constipation
Combine with Mg

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25
What two transmitters increase acid production?
``` M1/M3 = ACh H2 = Histamine ```
26
What are the three elements used in antacids?
Aluminum + Magnesium + Calcium
27
What is the product of antacids with H+?
Water + Neutral salt
28
When should antacids not be used? Why?
Renal failure | Mg will accumulate = CNS toxicity
29
What side effect do you see with Calcium as an antacid?
Creates CO2 = Burping
30
When should antacids be used, what types of Gi disorders?
Acidity in mild gastric disease | Don't work with ulcerations
31
When is Mg used to cause diarrhea in cattle, goats, and sheep?
Grain overload
32
What type of receptor are H2's linked with?
Gs = inc. cAMP
33
What are the four H2 antagonists?
Cimetidine Ranitidine Famotidine Nizatidine
34
What is the result of H2 antagonists?
Reduction in Gastric acid + Pepsin secretion
35
How should H2 antagonists be handled in renal patients?
50% the dose
36
What should you watch out for with cimetidine?
Many drug interactions due to CYPs inhibition
37
What can occur with ranitidine?
Increase motility through M stimulation + decrease in acid
38
When is ranitidine recommended?
Feline megacolon
39
When are H2 blockers benefical?
Gastric + Duodenal ulcerations Gastric erosions Esophageal reflux disease Gastritis
40
What H2 blocker is used in horses for ESGUS?
Ranitidine
41
Why are H2 blockers used in severe allergic reactions?
Decrease vasodilation effect of histamine on BV
42
How do proton pump inhibitors work?
Irreversible blockade of acid formation
43
How long does it take proton pump inhibitors to work?
2 to 5 days
44
Why do proton pump inhibitors have to be taken continuously?
Body will continue replacing H/K ATPase pumps
45
How should proton pump inhibitors be given?
Empty stomach for best absorption | Eat 30 min later
46
Where are proton pump inhibitors absorbed in the GI tract?
Intestine
47
What are the three proton pump inhibitors?
Omeprazole Esomeprazole Pantoprazole
48
When is a good time to use proton pump inhibitors in dogs?
Long-lasting acid suppression needed | Reduces risks of ulcers in dogs taking NSAIDs
49
What can proton pump inhibitors treat in horses?
EGGUS + ESGUS
50
What needs to be given with PPI in EGGUS?
Cytoprotectives
51
What is important to tell the client when giving them PPI's?
DO NOT CRUSH UP, need to be protected from stomach acid
52
What are the most effective drugs in healing ulcers?
PPI's
53
What are possible adverse reactions to PPI's?
Bacterial overgrowth Aspiration pneumonia Long-term increase in gastrin Gastric cancer
54
What does omeprazole inhibit? Do you need to worry about this?
P450's. No, doesnt inhibit enough of it
55
How do cytoprotective agents work?
Create physical barrier between gastric epi + gastric lumen
56
How does bismuth work?
Bind to ulcer bed = protective coating | Increases PG's = increased Bicard + decrease pepsin
57
What is important to remember about bismuth?
Toxic to cats and probably dogs due to salicylate
58
What are the side effects of sucralfate?
Constipation + Stomach upset
59
Why does sucralfate cause constipation?
Aluminum
60
When is sucralfate used in horses?
EGGUS
61
What is used with sucralfate in EGGUS?
omeprazole
62
What is misoprostol?
Synthetic PG's E1 analogue
63
When is misoprostol used?
NSAID use in older dogs
64
What side effects can occur with misoprostol?
Diarrhea + Abdominal cramps | Increase nephrotoxicity of other drugs
65
What does erythromycin stimulate?
Motilin
66
What does cisapride stimulate?
Serotonin
67
What are the two prokinetic D2 antagonists?
Metoclopramide + Doperiodone
68
What do the prokinetic, D2 antagonists do?
Increase ACh release via D2 blockage | Reduce gastroesophageal reflux via increase sphincter tone
69
What prokinetic drug is used in cats and dogs?
Metoclopramide
70
What side effect can occur with metoclopramide? Why?
Can get into CNS Excitement in horses + Anxiety + Involuntary movements Increase potlactin
71
When is metoclopramide used in dogs?
Vomiting disorders Delayed gastric emptying (post-operative) Decrease gastroesophageal reflux
72
What is important to know about metoclopramide?
NOT APPROVED IN FOOD ANIMALS
73
What is domperidone used for?
Increase prolactin secretion Treat fescue toxicity + agalactia in mares Vomiting + Reflux
74
When is bethanechol used in dogs? Why?
Dogs have striated muscle in esophagus Increases contraction Treatment of megasesophagus Cattle = cecal dilatation
75
When is erythromycin used?
Diabetic gastroparesis in dogs
76
What does Serotonin increase cause?
Increase ACh = increase motility SM
77
When is ipecac used?
After ingestion of toxins or drug overdose
78
How does apomorphine work?
Stimulates D2 in CTZ
79
When should you NEVER induce vomiting?
If animal has swallowed strong acid or alkali compound
80
What is really good at making cats vomit?
Xylazine
81
What is a neurokinin antagonist in vet medicine?
Maropitant
82
What does a neurokinin antagonist do?
Inhibit Substance P on NK1 receptor
83
What are neurokinin antagonoist used for?
Acute vomiting Motion sickneess Chemotherapy