H2 blocker

H2 Blocker

H2 blockers, also known as H2-receptor antagonists, are a class of medications that reduce the production of stomach acid. They are commonly used in the treatment of conditions such as gastroesophageal reflux disease (GERD), peptic ulcer disease, and Zollinger-Ellison syndrome.

Mechanism of Action

H2 blockers work by blocking the action of histamine on the H2 receptors of the parietal cells in the stomach lining. Histamine is a chemical that stimulates the secretion of gastric acid. By inhibiting this action, H2 blockers decrease the volume and concentration of stomach acid.

Common H2 Blockers

Some of the most commonly used H2 blockers include:

• Cimetidine (Tagamet)
• Ranitidine (Zantac)
• Famotidine (Pepcid)
• Nizatidine (Axid)

Indications

H2 blockers are indicated for the treatment of:

• Gastroesophageal reflux disease (GERD)
• Peptic ulcer disease
• Zollinger-Ellison syndrome
• Dyspepsia
• Stress ulcer prophylaxis in critically ill patients

Side Effects

While H2 blockers are generally well-tolerated, they can cause side effects in some individuals. Common side effects include:

• Headache
• Dizziness
• Diarrhea
• Constipation
• Fatigue

Rare but serious side effects may include:

• Confusion (especially in the elderly)
• Gynecomastia (with cimetidine)
• Hepatotoxicity

Drug Interactions

H2 blockers can interact with other medications, potentially altering their effects. For example, cimetidine is known to inhibit cytochrome P450 enzymes, which can affect the metabolism of drugs such as warfarin, phenytoin, and theophylline.

Comparison with Proton Pump Inhibitors

H2 blockers are often compared to proton pump inhibitors (PPIs), another class of acid-reducing medications. While both classes reduce stomach acid, PPIs are generally more effective for severe acid-related conditions. However, H2 blockers may be preferred for milder symptoms or for patients who cannot tolerate PPIs.

Also see

• Proton pump inhibitor
• Antacid
• Gastroesophageal reflux disease
• Peptic ulcer disease
• Histamine