H2-receptor antagonists

H2-receptor antagonists

  • H2-receotor antagonists (H2 Blockers) suppress gastric acid secretion.


  • H2 Blockers work by blocking signals generated by histamine receptors on cells that are responsible for acid secretion.


  • H2 blockers begin working within an hour. H2 Blockers, however, usually only work up to 12 hours.


  • H2 are capable of healing duodenal ulcers, relieving symptoms, and preventing complications. They are well tolerated and have low side effects


  • GERD that occurs 30-60 min PC and when a patient bends over or lies down, results from irritation of the esophagus by stomach acid should be treated with acid suppression therapy such as antacids (neutralizes stomach acid) or histamine -2 receptor antagonist or PPI (Prilosec).


  • H2 blockers are given after meals and HS.


  • Do not take within 2 hrs. of antacid.


  • Do not use PPI and H2 together.


  • H2 are less expensive and are also effective. If patient does not see results within a few days, increase dosage of med or change from H2 to PPI.


  • Not very effective for healing or preventing gastric ulcers, but do prevent duodenal ulcer.


  • Monitor liver enzymes and platelets when taking H2.


  • Nizatidine (Axid) is a good substitute for Tagamet.


  • Excessive use of histamine H-2 receptor antagonists leads to pharmacological tolerance and decrease effectiveness over time.


  • Pylori infection, NSAIDs and Smoking all contributes to Peptic Ulcer formation.


  • The Urea Breath test and the Stool Antigen tests are ordered to detect Helicobacter Pylori (H.Pylori).


  • PUD (peptic ulcer) caused by helicobacter Pylori is treated with: clarithromycin (Biaxin), Amoxicillin, PPI (Prilosec).


  • Cimetidine (Tagamet) and Calcium Channel Blockers (CCBs) have a drug interaction. Because of this, the CCB’s may be increased because cimetidine (Tagamet) may decrease the metabolism of CCBs.


  • Cimetidine (Tagamet) is not used much due to many DDI (Coumadin, theophylline, lidocaine).


  • Dines are H2 receptors and the prazole are PPI.


  • SIDE EFFECTS: HA, dizziness, fatigue, somnolence, and either diarrhea or constipation. These side effects are most likely to appear in the elderly and/or patients with decreased renal function, and metabolic/endocrine changes, such as: gynecomastia, low sperm count and CNS changes (disorientation, hallucinations).


H2-receptor antagonists:

Cimetidine (Tagamet)

Famotidine (Pepcid)

Nizatidine (Axid)

Ranitidine (Zantac)