H2 blockers

H2 Blockers

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 production of gastric acid. By inhibiting this action, H2 blockers decrease the volume and concentration of stomach acid.

Common H2 Blockers

Several H2 blockers are available, both over-the-counter and by prescription. These include:

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

Clinical Uses

H2 blockers are primarily used to treat conditions associated with excessive stomach acid production. These include:

• Gastroesophageal Reflux Disease (GERD): H2 blockers can help relieve symptoms such as heartburn and acid regurgitation.
• Peptic Ulcer Disease: They promote healing of ulcers in the stomach and duodenum by reducing acid secretion.
• Zollinger-Ellison Syndrome: A rare condition characterized by tumors that cause excessive acid production, where H2 blockers can help manage symptoms.

Side Effects

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

• Headache
• Dizziness
• Diarrhea or constipation
• Fatigue

Rarely, more serious side effects can occur, such as:

• Confusion, especially in the elderly
• Cardiac arrhythmias
• Blood disorders

Drug Interactions

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

History

H2 blockers were first developed in the 1960s and revolutionized the treatment of acid-related disorders. Cimetidine was the first H2 blocker introduced to the market in 1976, followed by other agents with improved safety profiles and fewer drug interactions.

Also see

• Proton Pump Inhibitors
• Antacids
• Gastroesophageal Reflux Disease
• Peptic Ulcer Disease