*GI drugs

Question 1

Antacids

Answer 1

Antacids work through chemical neutralization of
gastrointestinal acids but do not treat the production of gastric
acid, therefore tend to be used to relieve symptoms only

Question 2

Examples of Proton Pump Inhibitors (PPI)

Answer 2

• Omeprazole
• Lansoprazole
  *

Question 3

Indications of Omeprazole

Answer 3

• GERD
• Gastric ulcer
• Gastric ulcer prophylaxis (NSAID associated)
• Hypersecretory Disorders
• H pylori infection:

Question 4

Mechanism of action of omeprazole (PPI)

Answer 4

• Irreversibly inhibits gastric parietal cell H+-K+-ATPase,
  thereby inhibiting gastric acid secretion

Question 5

Adverse effects of Omeprazole (PPI)

Answer 5

• Headache,
• constipation or diarrhea,
• xerostomia (dry mouth)
• flatulence

Question 6

H2 RECEPTOR BLOCKERS

Answer 6

• Ranitidine [Zantac®]
• Famotidine [Pepcid®]
• Cimetidine [Tagamet®]
• Nizatidine

Ranitidine was introduced in 1981 and became the world’s top-selling drug in 1988; it’s
considered safer and more potent
• Ranitidine was pulled off the marked in April 2020 after finding carcinogenic contaminants
• Cimetidine first came to market in 1976 and became a world-renowned top-selling drug

Question 7

Indications of Famotidine (H2 blocker)

Answer 7

• GERD
• Duodenal/gastric ulcer:

Question 8

Mechanism of action of Famitidine

Answer 8

• Block histamine release from enterchromaffin cells in response to gastrin or vagal stimulation by selective competitive antagonism of parietal cell H2 receptors
• Acid secretion in response to direct stimulation of the parietal cell by gastrin or vagal stimulation is reduced in presence of H2 receptor blockade

• Like H1 antihistamines, the H2 antihistamines are actually considered to act more like inverse agonists rather than pure antagonists

Question 9

Adverse reactions of Famotidine (H2 blocker)

Answer 9

Common:

• Headache,
• dizziness

Serious:

• Food and drug allergies,
• psychosis,
• depression,
• reversible impotence,
• gynecomastia