Histamine-2 Receptor Blockers

Histamine-2 receptor antagonists, also known as H2 blockers, are drugs that prevent or block the production of gastric (stomach) acid. These drugs are used to heal ulcers and relieve the symptoms and pain associated with gastroesophageal reflux disease (GERD). A pump in the stomach releases hydrochloric acid when stimulated by histamine. H2 blockers prevent histamine from stimulating this pump, thereby reducing the amount of acid that is released into the stomach. H2 blockers are available over-the-counter (OTC) or by prescription.

Drugs in this Class
Ranitidine Tablets (Zantac 75, Zantac Tablets)
Cimetidine Tablets (Tagamet, Tagamet HB)
Ranitidine Oral Syrup (Zantac Syrup)
Nizatidine Capsules (Axid Capsules, Nizatadine Capsules)
Ranitidine Effervescent Tablets or Granules (Zantac EFFERdose)
Famotidine Chewable Tablets (Pepcid AC Chewable Tablets)
Ranitidine Injection (Ranitidine Hydrochloride Injection, Zantac Injection)
Famotidine Suspension (Pepcid Suspension)

Summarizing the Evidence

  • All of the prescription strength H2 blockers appear to be similar in how well they work, in dosing frequency, side effects, and drug interactions, except for cimetidine (Tagamet), whose drug interaction potential is greater than those of the other drugs in this class. In general, the studies examined did not make any distinctions between the available H2 blockers in regards to their effectiveness in the treatment of the various stomach acid-related gastrointestinal disorders.

  • Over-the-counter (OTC) and prescription strength H2 blockers are not interchangeable. OTC H2 blockers are one-half of the lowest available dose of their prescription strength counterpart. Thus, OTC H2 blockers are generally not strong enough to treat and heal ulcers. Two exceptions exists--Maximum Strength Pepcid AC and Maximum Strength Zantac are available OTC but contain prescription strength famotidine (Pepcid) and ranitidine (Zantac).

Dosing and Administration

  • Dosing of H2 blockers will depend on what caused the ulcer and where the ulcer is located (either in the stomach or in the intestine). For ulcer healing, cimetidine is typically dosed once, twice, or four times daily. Famotidine, nizatidine, and ranitidine are typically dosed once or twice daily for this purpose. After the ulcer is healed, to maintain the healing, all of the H2 blockers are typically dosed once daily at bedtime.

Generic Availability

  • All prescription strength H2 blockers are available in generic formulations. Although not generally used for treating peptic ulcer disease, all over-the-counter (OTC) H2 blockers are available in various store-branded products that are typically less expensive.

Drug Interactions

Some interactions between medications can be more severe than others. The best way for you to avoid harmful interactions is to tell your doctor and/or pharmacist what medications you are currently taking, including any over-the-counter products, vitamins, and herbals. For specific information on how the drugs interact and the severity of the interaction, please use our Drug Interactions Checker.

Side Effects

To view specific side effect information, please use our Side Effect Checker.

Additional Information

Referenes:

  1. Berardi RR, Kroon L, McDermott JH and Newton GD. Handbook of Nonprescription Drugs. 15th edition. Acid-Peptic Products. American Pharmaceutical Association; Washington DC. 2006.

  2. Knodel LC, ed. Nonprescription Products: Formulations and Features; 98-99. Acid-Peptic Products. American Pharmaceutical Association; Washington DC. 1998. pg: 162.

  3. Berardi RR, Welage LS. Peptic Ulcer Disease. In: Pharmacotherapy A Pathophysiologic Approach. 6th ed. Dipiro JT, Talbert RL, Yee GC et al. (eds). McGraw-Hill. New York. 2005. pg. 629-648.

  4. Drugdex Database. In: Thomson-Micromedex. Greenwood Village, CO. 2006.

  5. Drug Facts and Comparisons. Wolters Kluwer Health. St. Louis, MO; 2007.

  6. Product Information: Tagamet(R), cimetidine. SmithKline Beecham Pharmaceuticals, Philadelphia, PA, 1999.

  7. Dobrilla G, de Pretis G, Felder M et al. Endoscopic double-blind controlled trial of ranitidine vs placebo in the short-term treatment of duodenal ulcer. Hepatogastroenterology. 1981b;28:49-52.

  8. Marks IN, Wright JP, Denyer M et al. Ranitidine heals duodenal ulcers. S Afr Med J. 1982;61:152-154.

  9. Graham DY, Akdamar K, Dyck WP et al: Healing of benign gastric ulcer: comparison of cimetidine and placebo in the United States. Ann Intern Med 1985; 102:573-576.

  10. Paoluzi P, Torsoli A, Porro GB et al. Famotidine (MK-208) in the treatment of gastric ulcer. Digestion. 1985;32(suppl 1):38-44.

  11. Porro GB. Famotidine in the treatment of gastric and duodenal ulceration: overview of clinical experience. Digestion. 1985;32(suppl 1):62-69.

  12. Product Information: Axid(R), nizatidine. Physician's Desk Reference (electronic version), Micromedex, Inc, Englewood, CO, 1998.

  13. Hirschowitz BI, DeLuca V, Graham D et al. Treatment of benign chronic gastric ulcer with ranitidine: a randomized, double-blind, and placebo-controlled six week trial. J Clin Gastroenterol. 1986;8:371-376.

  14. Schulz TB, Berstad A, Rydning A et al. Treatment of gastric ulcer with ranitidine. Scand J Gastroenterol. 1984;19:119-121.

Last Updated: March 2008

Note: The above information is intended to supplement, not substitute for, the expertise and judgment of your physician, pharmacist, or other healthcare professional. It should not be construed to indicate that the use of the product is safe, appropriate, or effective for you. Consult your healthcare professional before taking any medication.

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