Clinical data
Pronunciation /fəˈmɒtɪdn/
Trade names Pepcid, others
AHFS/Drugs.com Monograph
MedlinePlus a687011
License data
  • AU: B1
  • US: B (No risk in non-human studies)
    Routes of
    Oral (tablets), Intravenous
    ATC code
    Legal status
    Legal status
    Pharmacokinetic data
    Bioavailability 40–45% (oral)[1]
    Protein binding 15–20%[1]
    Metabolism hepatic
    Elimination half-life 2.5–3.5 hours[1]
    Excretion Renal (25-30% unchanged [Oral])[1]
    CAS Number
    PubChem CID
    ECHA InfoCard 100.116.793
    Chemical and physical data
    Formula C8H15N7O2S3
    Molar mass 337.449 g/mol
    3D model (JSmol)

    Famotidine, sold under the trade name Pepcid among others, is a histamine H2 receptor antagonist that inhibits stomach acid production. It is commonly used in the treatment of peptic ulcer disease and gastroesophageal reflux disease.

    Unlike cimetidine, the first H2 antagonist, famotidine has no effect on the cytochrome P450 enzyme system, and does not appear to interact with other drugs.[2]

    It was discovered in 1979.[3]

    Medical uses

    Famotidine is also given to dogs and cats with acid reflux.[15] Famotidine has been used in combination with an H1 antagonist to treat and prevent urticaria caused by an acute allergic reaction.[16]


    Certain preparations of famotidine are available over the counter (OTC) in various countries. In the United States and Canada, 10 mg and 20 mg tablets, sometimes in combination with an antacid,[17][18] are available OTC. Larger doses still require a medical prescription.

    Formulations of famotidine in combination with ibuprofen were marketed by Horizon Pharma under the trade name Duexis.[19]

    Side effects

    Side effects associated with famotidine use include headache, dizziness, and constipation or diarrhea.[20]


    Famotidine was developed by Yamanouchi Pharmaceutical Co.[21] It was licensed in the mid-1980s by Merck & Co.[22] and is marketed by a joint venture between Merck and Johnson & Johnson. The imidazole ring of cimetidine was replaced with a 2-guanidinothiazole ring. Famotidine proved to be nine times more potent than ranitidine, and thirty-two times more potent than cimetidine.[23]

    It was first marketed in 1981. Pepcid RPD orally disintegrating tablets were released in 1999. Generic preparations became available in 2001, e.g. Fluxid (Schwarz) or Quamatel (Gedeon Richter Ltd.).

    In the United States and Canada, a product called Pepcid Complete, which combines famotidine with an antacid in a chewable tablet to quickly relieve the symptoms of excess stomach acid, is available. In the UK, this product was known as Pepcidtwo prior to its discontinuation in April 2015.[24]

    Famotidine suffers from poor bioavailability (50%), as it is poorly soluble in the low pH of the stomach. When used in combination with antacids, it promotes local delivery of these drugs to the receptor of the parietal cell wall. Therefore, researchers are developing innovative formulations of tablets, such as gastroretentive drug delivery systems. Such tablets are retained in the stomach for a longer period of time, thereby improving the bioavailability of drugs. Local delivery also increases bioavailability at the stomach wall receptor site and increases the efficacy of drugs to reduce acid secretion.[25]


    Famotidine has been investigated as an adjunct in treatment-resistant schizophrenia. In one trial, it caused a 10% reduction in schizophrenic symptom severity in treatment-resistant patients.[26]

    See also


    1. 1 2 3 4 Truven Health Analytics, Inc. DRUGDEX® System (Internet) [cited 2013 Oct 10]. Greenwood Village, CO: Thomsen Healthcare; 2013.
    2. Humphries TJ, Merritt GJ (August 1999). "Review article: drug interactions with agents used to treat acid-related diseases" (pdf). Aliment. Pharmacol. Ther. 13 (Suppl 3): 18–26. doi:10.1046/j.1365-2036.1999.00021.x. PMID 10491725.
    3. Fischer, Janos (2010). Analogue-based Drug Discovery II. John Wiley & Sons. p. 4. ISBN 978-3-527-63212-1.
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    6. Borody, TJ; Andrews, P; Fracchia, G; Brandl, S; Shortis, NP; Bae, H (October 1995). "Omeprazole enhances efficacy of triple therapy in eradicating Helicobacter pylori". Gut. 37 (4): 477–81. doi:10.1136/gut.37.4.477. PMC 1382896. PMID 7489931.
    7. Hu, FL; Jia, JC; Li, YL; Yang, GB (2003). "Comparison of H2-receptor antagonist- and proton-pump inhibitor-based triple regimens for the eradication of Helicobacter pylori in Chinese patients with gastritis or peptic ulcer". The Journal of international medical research. 31 (6): 469–74. doi:10.1177/147323000303100601. PMID 14708410.
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    9. Fujiwara, Y; Higuchi, K; Nebiki, H; Chono, S; Uno, H; Kitada, K; Satoh, H; Nakagawa, K; Kobayashi, K; Tominaga, K; Watanabe, T; Oshitani, N; Arakawa, T (June 2005). "Famotidine vs. omeprazole: a prospective randomized multicentre trial to determine efficacy in non-erosive gastro-oesophageal reflux disease". Alimentary Pharmacology & Therapeutics. 21 Suppl 2: 10–8. doi:10.1111/j.1365-2036.2005.02468.x. PMID 15943841.
    10. La Corte, R; Caselli, M; Castellino, G; Bajocchi, G; Trotta, F (June 1999). "Prophylaxis and treatment of NSAID-induced gastroduodenal disorders". Drug safety. 20 (6): 527–43. doi:10.2165/00002018-199920060-00006. PMID 10392669.
    11. Laine, L; Kivitz, AJ; Bello, AE; Grahn, AY; Schiff, MH; Taha, AS (March 2012). "Double-blind randomized trials of single-tablet ibuprofen/high-dose famotidine vs. ibuprofen alone for reduction of gastric and duodenal ulcers". The American Journal of Gastroenterology. 107 (3): 379–86. doi:10.1038/ajg.2011.443. PMC 3321505. PMID 22186979.
    12. Escolano, F; Castaño, J; López, R; Bisbe, E; Alcón, A (October 1992). "Effects of omeprazole, ranitidine, famotidine and placebo on gastric secretion in patients undergoing elective surgery". British journal of anaesthesia. 69 (4): 404–6. doi:10.1093/bja/69.4.404. PMID 1419452.
    13. Vila, P; Vallès, J; Canet, J; Melero, A; Vidal, F (November 1991). "Acid aspiration prophylaxis in morbidly obese patients: famotidine vs. ranitidine". Anaesthesia. 46 (11): 967–9. doi:10.1111/j.1365-2044.1991.tb09860.x. PMID 1750602.
    14. Jahr, JS; Burckart, G; Smith, SS; Shapiro, J; Cook, DR (July 1991). "Effects of famotidine on gastric pH and residual volume in pediatric surgery". Acta anaesthesiologica Scandinavica. 35 (5): 457–60. doi:10.1111/j.1399-6576.1991.tb03328.x. PMID 1887750.
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    19. Drugs.com duexis
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