Gastrointestinal (H2 Receptor Antagonists)

Question 1

Examples of drug (H2 Receptor Antagonists)

Answer 1

• Ranitidine
• Cimetidine
• Famotidine
• Nizatidine

Question 2

Mechanism of action (H2 Receptor Antagonists)

Answer 2

• Histamine binds to H2 receptors on gastric parietal cells stimulating gastric acid secretion
• Drugs antagonise the effect of histamine at these H2 receptors
• Reduced cAMP and hence reduced activity of H+/K+ ATPase pump

Question 3

Indications (H2 Receptor Antagonists)

Answer 3

• Peptic ulcer
• Gastro-oesophageal reflux disease
• Zollinger-Ellison syndrome

Question 4

Side-effects (H2 Receptor Antagonists)

Answer 4

• Headache
• Dizziness
• Diarrhoea
• Reduced B12 absorption
• Gynaecomastia

Question 5

Important pharmacokinetics/pharmacodynamics (H2 Receptor Antagonists)

Answer 5

• Cimetidine is an inhibitor of cytochrome P450 enzymes.

Question 6

Patient information (H2 Receptor Antagonists)

Answer 6

• Avoid high protein diet

- Take without regard to meals