H2 Blockers Lecture Notes

Overview

• H2 blockers, also known as histamine H2-receptor antagonists, reduce stomach acid production.
• Common types include cimetidine (Tagamet), famotidine, nizatidine, and ranitidine (withdrawn).
• Histamine stimulates acid production, and H2 blockers prevent this interaction.

Functions

• Decrease acid production in the stomach.
• Help reduce symptoms of acid reflux, heartburn, and aid in healing ulcers.

Uses

• Treat and reduce acid reflux and gullet inflammation (oesophagitis), also known as GORD.
• Treat ulcers in the stomach and duodenum.
• Heal ulcers related to NSAIDs use.
• Manage Zollinger-Ellison syndrome, which involves excessive acid secretion.
• Previously used to treat Helicobacter pylori infections, now largely replaced by proton pump inhibitors.

Comparison with Proton Pump Inhibitors

• Proton pump inhibitors (PPIs) like omeprazole, lansoprazole, and others are often preferred for reducing stomach acid.
• PPIs are usually the first choice due to their effectiveness.
• H2 blockers may be prescribed if PPIs cause side effects.

Administration

• Can provide quick relief for symptoms like heartburn.
• May take longer for effects on ulcers.
• Available over the counter, but long-term use should be consulted with a doctor.
• May be prescribed for daily use or as needed.

Side Effects

• Generally well-tolerated by most people.
• Common side effects include diarrhea, headache, dizziness, rash, and tiredness.

Considerations

• Not suitable for individuals with kidney problems or pregnant/breastfeeding women.
• Can interact with other medications like warfarin, phenytoin, and theophylline.

When to Consult a Doctor

• Symptoms worsen or serious gut disorders appear, such as:
  • Vomiting blood or coffee-ground vomit.
  • Blood in stools or black stools.
  • Unintentional weight loss.
  • Difficulty swallowing.
  • Persistent abdominal pain or vomiting.

Special Instructions

• Do not take antacids simultaneously with H2 blockers as they can affect absorption.

Article Information

• Reviewed by qualified clinicians.
• Latest version as of July 26, 2023.
• Next review due by July 24, 2028.