GI Pharmacology Flashcards

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1
Q

Risk factors of gastric and duodenal ulcers

A
  • Helicobacter pylori
  • NSAIDs
  • early gastric emptying
  • smoking + alcohol delay healing
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2
Q

Common causes of gastric + duodenal ulcers

A

Helicobacter pylori (most common)
NSAIDs

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3
Q

Example of alginates + antacids

A

Gaviscon

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4
Q

What class of drug is gaviscon?

A

Alginate + antacid

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5
Q

What are the uses of gaviscon?

A

GORD

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6
Q

What is the mechanism of action of gaviscon?

A
  • antacid: buffers stomach acid
  • alginic acid: increase stomach content viscosity + reduce reflux
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7
Q

What is gaviscon composed of?

A
  • alginic acid: sodium alginate
  • antacid: aluminium hydroxide/magnesium carbonate
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8
Q

What are adverse drug reactions of gaviscon?

A

Magnesium salts can cause diarrhoea
Aluminium salts can cause constipation

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9
Q

Why is the antacid part of gaviscon often composed of both aluminium hydroxide AND magnesium carbonate?

A
  • magnesium salts can cause diarrhoea
  • aluminium salts can cause constipation
  • attempt to balance out the adverse drug reactions
    .
  • magnesium hydroxide gastric pH higher + faster than aluminium hydroxide (AlHO has longer duration)
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10
Q

What are contradictions of gaviscon?

A
  • renal failure in Na+ + K+ containing preparations
  • diabetes mellitus in high sucrose conc preparations
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11
Q

What are important drug drug interactions of gaviscon?

A
  • Can reduce absorption of drugs so doses should be separated
  • Increased urine alkalinity can increases aspirin excretion
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12
Q

Examples of proton pump inhibitors

A

Omeprazole
Lansoprazole

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13
Q

What are the uses of PPIs?

A

Helicobacter pylori eradication
Peptic ulcers + relapse prevention
Co prescribed within NSAIDs

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14
Q

What is the mechanism of action of PPI?s

A

Irreversibly inhibition H+/K+ ATPase in parietal cells > reduction in acid secretion

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15
Q

What are adverse drug reactions of PPIs?

A
  • abdominal pain
  • diarrhoea
  • constipation
  • headache
  • dizziness
  • drowsiness
  • can mask symptoms of gastro-oesophageal cancer
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16
Q

What are important drug drug interactions of PPIs?

A
  • Omeprazole is a CYP inhibitors > reduced clopidogrel action
  • increased effects of warfarin + phenytoin
17
Q

What is the suffix of PPIs?

A

-prazole

18
Q

Example of H2 receptor antagonists

A

Ranitidine

19
Q

What are uses of H2 receptor antagonists?

A

Peptic ulcers
GORD

20
Q

What is the mechanism of action of H2 receptor antagonists?

A
  • Inhibition of H2 receptors
  • Reduces release of histamines
  • Reduces acid secretion from parietal cells
21
Q

What are adverse drug reactions of H2 receptor antagonists?

A

Generally well tolerated
Diarrhoea
Headache
Can mask symptoms of gastro-oesophageal cancer

22
Q

What are important drug drug actions of H2 receptor antagonists?

A

Few common

23
Q

A patient is taking clopidogrel + the doctor wants to prescribe a PPI for their duodenal ulcer. Which PPI should they be given + why?

A

Lansoprazole
Omeprazole is a CYP inhibitor > reduces clopidogrel action

24
Q

How should a PPI be prescribed?

A

Shorted effective duration at lowest effective dose

25
Q

Treatment of Helicobacter pylori infection - triple therapy options

A

Lansoprazole + clarithromycin + amoxicillin
(metrondiazole if allergic to amoxicillin)

26
Q

Diagnosis of Helicobacter pylori infection

A

Positive urea breath test

27
Q

Example of aminosaicylates

A

Mesalazine
Sulfasalazine

28
Q

What class of drug is mesalazine?

A

Aminosalicylate

29
Q

What is the use of mesalazine?

A

First line treatment of UC

30
Q

What is the mechanism of action of mesalazine?

A

Release of 5-aminosalsylic acid
Anti-inflammatory effect
Topic action at colon

31
Q

What are adverse drug reactions of mesalazine?

A

Nausea
Dyspepsia
Leukopenia (rare)

32
Q

What are important drug drug interactions of mesalazine?

A

Increased breakdown in presence of PPI due to increased pH

33
Q

Compare the use of mesalazine + sulfasalazine

A

Mesalazine - first line for UC
Sulfasalazine - RA

34
Q

The half life of PPIs is only a few hours, why is acid secretion inhibited for longer than this?

A

PPIs irreversibly inhibit H+/K+ ATPase in parietal cells

35
Q

What drug is used first line in treatment of UC?

A

Mesalazine