Lecture 20 - GI Pharmacology Flashcards

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1
Q

What is the most common location of pain for gastric or duodenal ulcers?

A

Epigastric pain

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2
Q

What are some symptoms of gastric or peptic ulcerations?

A

Bleeding
Perforation
Scarring and possible obstruction

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3
Q

What are some risk factors of gastric acid or peptic ulcers?

A

Early gastric emptying
Imbalance between normal acid levels and feedback
Helicobacter pylori
NSAIDs
Smoking and alcohol delay healing of ulcers.

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4
Q

Why do NSAIDs increase risk of gastric ulceration?

A

Reduced prostaglandins which normally inhibit the production of gastric acid

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5
Q

What cells produce histamine stimulating gastric acid production?

A

Enterochromaffin cells

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6
Q

What are the 3 main stimulatory transmitters for gastric acid production?

A

ACh
Histamine
Gastrin

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7
Q

What is an example of a combined alginates and antacids?

A

Gaviscon

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8
Q

What is the purpose of antacids and alginates?

A

Antacids = buffering stomach acid
Alginic acid = inc stomach content viscosity and reduce reflux

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9
Q

What is contained in gaviscon?

A

Alginic acid = sodium alginate
Antacids = aluminium hydroxide/magnesium carbonate

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10
Q

What are the adverse effects of magnesium salt and then aluminium salts used as antacids?

A

Mg salts = diarrhoea
Aluminium salts = constipation

AC
MD

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11
Q

Why are aluminium hydroxide. And magnesium carbonate both taken at the same time if they are both antacids?

A

Mg salts cause diarrhoea and Aluminium salts can cause constipation

So balance the side effects

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12
Q

What are the warnings and contraindications to alginates and antacids?

A

Na+ and K+ containing preparations should be carefully used in renal failure

High conc sucrose in some solutions so be careful with hyperglycaemia in DM

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13
Q

What are the important drug drug interactions of alginates and antacids?

A

Reduce absorption of many drugs
Can inc urine alkalinity increasing aspirin excretion

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14
Q

What are some proton pump inhibtors?

A

Omeprazole
Lansoprazole

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15
Q

What is the mechanism of action of proton pump inhibitors like omeprazole and lansoprazole?

Why are they so effective?

A

Irreversibly inhibit the H+/K+ ATPase in gastric parietal cells

Inhibit the final stage in stomach acid production

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16
Q

What are some adverse effects of proton pump inhibtors like omeprazole and lansoprazole?

A

GI disturbance (abdominal pain, constipation, diarrhoea)
Headache , dizziness
Drowsiness/confusion

17
Q

What are some warnings and contraindications of proton pump inhibitors?

A

Mask symptoms of gastro-oesophageal cancer
Osteoporosis - fracture risk

18
Q

What are some importnat drug drugs interactions of omeprazole?

A

CYP inhibitor so omeprazole reduces clopidogrel activation

PPIs can increase effects of warfarin and phenytoin

19
Q

What are PPIIs often prescribed alongside with?

A

NSAID
Steroid

20
Q

What is an example of H2 receptor antagonists?

A

Famotidine

21
Q

How do H2 receptor antagonists work?
(Famotidine)

A

Inhibts H2 receptors since histamine release contributes to proton pump. Activation

22
Q

How do H2 receptor anatagonists like Famotidine compare in their action to proton pump inhibtors like omeprazole and lansoprazole?

A

PPIs act at the final step of acid production so are very effective

H2 receptor antagonists dont act as far down the pathway so only partially reduce acid secretion

23
Q

What are the adverse effects of Famotidine? (H2 receptor antagonists)

A

Generally well tolerated
Diarrhoea
Headache

24
Q

What are the warnings/contrainidactions of Famotidine? (H2 receptor antagonists)

A

Mask symptoms of gastro-oesophageal cancers
Renal impairment

25
Q

What are the DDIs of Famotidine? (H2 receptor antagonists)

A

Very few

26
Q

When should Helicobacter pylori infection be suspected?

A

Duodenal or gastric ulcerations

27
Q

What test is used to determine a Helicobacter pylori infection?

A

Urea breath test

Breath in C13 and H-pylori will convert urea to ammonia and ammooonia will be breathed out containing C13

28
Q

How is Helicobacter pylori infection treated?

A

One week triple therapy
PPI + 2 anti bacterial agents

29
Q

What mediations are given for Helicobacter pylori infection?

A

Lansoprazole + Clarithromycin + Amoxicillin

Lansoprazole + Clarithromycin + Metronidazole (when allergic to penicillin)

30
Q

What are some examples of aminosalicylates?

A

Mesalazine
Sulfalazine

31
Q

What is the first line treatment for ulcerative colitis?

A

Mesalazine

32
Q

What is the mechanism of action of Mesalazine in ulcerative colitis?

A

Enteric coated tablet limits gastric breakdown leading to release of 5-amino salicylic acid topical action at the colon

33
Q

Why does Mesalazine not work in rheumatoid arthritis but sulfasalazine does?

A

Sulfa group good for RA

34
Q

What are the adverse effects of aminosalicylates (Mesalazine)?

A

GI disturbance (nausea and dyspepsia)

Leukopenia (rare)

35
Q

What are the warning/contraindications to Mesalazine (aminosalicylates)?

A

They’re like aspirin so may have similar hypersensitivity to them

36
Q

What aer some DDI for Mesalazine (aminosalicylates)?

A

Using PPIs may lead to the enteric coated tablets breaking down quicker due to. Increased PH