How Do Histamine H2 Antagonists Work?

HistamineH2receptorantagonists (H2RAs) or H2-blockers are a class ofstomachacid-suppressing agents and are used to treatgastroesophageal refluxandduodenalulcers. H2RAs suppress the release of stomach acid to treat conditions caused by excess acid secretion. The stomach wall consists of acid-secreting cells (parietalcells), which have histamine receptors (H2) on them. Usually, after a meal, the stomach secretes ahormone(gastrin), which stimulates histamine release from cells called enterochromaffin-like cells. The released histamine binds to the H2 receptors located on parietal cells to release stomach acid.

H2RAs compete with histamine to bind to the H2 receptor, thereby inhibiting the binding and action of histamine. By blocking the action of histamine, H2RAs prevent the release of stomach acid from the parietal cells.

As H2RAs suppress the release of stomach acid, they are mainly used to treat:

• Mildgastroesophagealrefluxdisease
• Gastricor duodenal ulcers
• Heartburn
• Indigestion
• Hypersecretory conditions

H2RAs, when administered orally, can cause the following side effects:

• Headache
• Dizziness
• Confusion
• Diarrhea
• Nausea
• Vomiting
• Drowsiness
• Gynecomastia(swollenmalebreast组织)
• Impotence
• Insomnia
• Itching
• Anxiety
• Abdominal pain

The information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with yourdoctoror药剂师to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking yourmedicationand never change your dose or frequency without consulting your doctor.

Genericand brand names of H2RA drugs include:

• Acid controller
• Act
• Axid
• Cimetidine
• Dyspep HB
• Famotidine
• Fluxid
• Nizatidine
• Pepcid
• Ranitidine
• TagametHB
• Zantac
• Zantac 150 maximum strength
• Zantac 75