Gastritis & peptic ulcer Flashcards

1
Q

What are the 3 agents used to reduce gastric acidity?

A
  1. Antacids
  2. H2-receptor antagonists
  3. PPIs
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2
Q

What are the 4 weak bases used in antacids?

A

NaHCO3
CaCO3
Mg(OH)2
Al(OH)3

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3
Q

What benefit does simethicone have when taken with antacids?

A

Antifoaming activity coalesces bubbles and reduces bloating.

Helps to reduce gastric distention, belching discomfort side effects.

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4
Q

In which patients is long-term antacid use contraindicated in?

A

Renal insufficiency
Patients on diuretics

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5
Q

What type of antacid causes osmotic diarrhoea?

A

Mg2+ antacids

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6
Q

What type of antacid causes constipation?

A

Al3+ antacids

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7
Q

Which type of antacid is most prone to reboud acid secretion?

A

Ca2+

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8
Q

Which types of antacids cause metabolic alkalosis/Milk-Alkali syndrome?

A

Na+ & Ca2+

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9
Q

Name 3 H2-receptor antagonists

A
  1. Famotidine
  2. Ranitidine
  3. Cimetidine
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10
Q

What is the MOA of famotidine?

A

Competitive inhibitor of H2 receptors on parietal cells; suppresses acid secretion by parietal cells

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11
Q

When is famotidine most effective?

A

At night

Noctornal acid secretion is mostly due to histamine release

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12
Q

What are the common adverse effects of famotidine & ranitidine?

Think of muscarinic antagonism

A

Headache
Nausea
Dry mouth

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13
Q

What are the severe adverse effects of famotidine & ranitidine?

A

Tachycardia
Blood dyscrasia
Blurred vision
MSK pain

blood dyscrasia - imbalance of blood cell types

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14
Q

What are the severe adverse effects of cimetidine?

A

Mental confusion

Anti-androgenic, inhibits estradiol metabolism, increases serum prolactin
gynaecomastia, impotence, glaactorrhoea

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15
Q

What is the MOA of omeprazole?

A

Irreversibly inhibits H+/K+-ATPase in parietal cells

IRREVERSIBLE!!!

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16
Q

What is the main function of the enteric coating around omeprazole?

A

Protects against early activation by stomach acidicity

17
Q

Why must early activation of omeprazole be avoided?

A

Activated omeprazole has poor bioavailability; will not be absorbed by the intestines and delivered to the parietal cells via the blood

18
Q

What is the DOA of omeprazole?

A

24H

IRREVERSIBLE INHIBITION OF PROTON PUMP

19
Q

When should omeprazole be given?

A

1H before food

Proton pumps must be present and active before omeprazole can exert its effect

20
Q

What are the common adverse effects of PPIs?

A

Headache
Nausea
Dizziness
Diarrhoea
Flatulence
Rash

21
Q

What are the severe adverse effects of PPIs?

A

Increased risk of C. diff, MDR organism infections
Hypomagnesaemia
Microscopic colitis
Lupus
Kidney disease

MDR - multi-drug resistant

22
Q

What are the 3 cytoprotective agents?

A
  1. Sucralfate
  2. Bismuth compounds
  3. Misoprostol
23
Q

What is the MOA of sucralfate?

A
  1. Breaksdown into sucrose sulphate (strong -ve charge) –> binds to +ve charged proteins at ulcer crater –> forms viscous, tenacious gel that prevents further acid attack
  2. Stimulates mucosal prostaglandins
24
Q

When should sucralfate be administered?

A

1H before meals

25
Q

What are the adverse effects of sucralfate?

Hint - contains Al3+

A

Constipation
Impairs absorption of other drugs

Binds to other drugs preventing absorption

26
Q

What is the MOA of bismuth compounds?

A
  1. Forms a protective layer protecting ulcers from acid & pepsin
  2. Stimulates mucus & HCO3- secretion
27
Q

What 2 drugs have weak anti-microbial activity against H. pylori?

A

Omeprazole
Bismuth compounds

28
Q

What drug is assosciated with darkening of tongue & blackening of stools?

A

Bismuth compounds

29
Q

What are the servere adverse effects of bismuth compounds?

A

Encephalopathy

30
Q

What group of patients is bismuth use contraindicated in?

A

Renal insufficiency

31
Q

What is the MOA of misoprostol?

A

Synthetic PGE1 analogue that binds to PGE2 receptors, mimicking the gastric protective effects of prostaglandins

Increase HCO3- & mucus sevretion, increase mucosal blood flow, decrease gastric acid secretion

32
Q

What are the adverse effects of misoprostol?

Hint - BAAD

A

Bone pain
Abortion
Abdominal pain
Diarrhoea

33
Q

What is the triple therapy for H. pylori infection?

A

Clarithromycin
Amoxicillin or Metronidazole
PPI

34
Q

Why is double antibiotic therapy required when treating H. pylori?

A

H. pylori becomes resistant to metronidazole & clarithromycin when given alone

35
Q

If triple therapy does not work for H. pylori infection, what is the second line treatment?

A

Add bismuth compound

36
Q

Why is PPI given alongside double antibiotic therapy during H. pylori infection?

A
  1. Reduce symptoms of peptic ulcer disease & allow for healing
  2. Makes antibiotics more effective