Famotidine: Wikis


Note: Many of our articles have direct quotes from sources you can cite, within the Wikipedia article! This article doesn't yet, but we're working on it! See more info or our list of citable articles.


From Wikipedia, the free encyclopedia

Systematic (IUPAC) name
3-([2-(diaminomethyleneamino)thiazol- 4-yl]methylthio)- N'-sulfamoylpropanimidamide
CAS number 76824-35-6
ATC code A02BA03
PubChem 3325
DrugBank APRD00296
ChemSpider 3208
Chemical data
Formula C 8H15N7O2S3  
Mol. mass 337.449 g/mol
Pharmacokinetic data
Bioavailability 20–66%
Protein binding 10–28%
Metabolism hepatic-less than 30%
Half life 2.5–4 hours (clinical half-life 8–12 hours)
Excretion Principally excreted unchanged in urine
Therapeutic considerations
Licence data

US FDA:link

Pregnancy cat. B1 (Au), B (U.S.)
Legal status S3/S4 (Au), POM/OTC (UK),
OTC/℞-only (U.S.)
Routes Oral, IV
 Yes check.svgY(what is this?)  (verify)

Famotidine (INN) (pronounced /fəˈmɒtɪdiːn/) is a histamine H2-receptor antagonist that inhibits stomach acid production, and it is commonly used in the treatment of peptic ulcer disease (PUD) and gastroesophageal reflux disease (GERD/GORD). It is commonly marketed by Johnson & Johnson/Merck under the trade names Pepcidine and Pepcid. 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.[1]


History and development

Famotidine was developed by Yamanouchi Pharmaceutical Co. [2] . It has been licensed in the mid-80s by Merck & Co.[3] 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 30 times more active than cimetidine.

It was first marketed in 1985. Pepcid RPD orally-disintegrating tablets (that are not swallowed) were released in 1999. Generic preparations became available in 2001, e.g. Fluxid (Schwarz) or Quamatel (Gedeon Richter Ltd.).

In the United States, a product called Pepcid Complete is available that combines famotidine with an antacid in a chewable tablet to ameliorate the relatively slow onset of effects. In the UK, this product is known as Pepcidtwo.

Famotidine suffers from poor bioavailability (50%), as famotidine is poorly soluble in acid pH e.g. stomach. Famotidine used in combination with antacids promotes local delivery of these drugs to the receptor of the parietal cell wall. Therefore researchers are developing innovative formulations of tablets, such gastroretentive drug delivery systems. Such tablets are retained in the stomach for a longer period of time and thereby improve 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.[4]

Clinical use

Certain preparations of famotidine are available over the counter (OTC) in various countries. In the United States, preparations of 10 mg and 20 mg tablets, sometimes in combination with a more traditional antacid, are available OTC. Larger doses still require a prescription.

Famotidine is given to surgery patients before operations to prevent post-operation nausea and to reduce the risk of aspiration pneumonitis.

Adverse effects

Adverse drug reactions are associated with famotidine use. In clinical trials, the most common adverse effects were headache, dizziness, and constipation or diarrhea.[5]


  1. ^ Humphries TJ, Merritt GJ (August 1999). "Review article: drug interactions with agents used to treat acid-related diseases". Aliment. Pharmacol. Ther. 13 Suppl 3: 18–26. doi:10.1046/j.1365-2036.1999.00021.x. PMID 10491725. http://www3.interscience.wiley.com/cgi-bin/fulltext/119090200.  
  2. ^ US4,283,408 (PDF version) (1981-08-11) Hirata , et al., Guanidinothiazole compounds, process for preparation and gastric inhibiting compositions containing them.  
  3. ^ "Sankyo Pharma". Skyscape Mediwire. 2002. http://mediwire.skyscape.com/main/Default.aspx?P=Content&ArticleID=23882. Retrieved 2009-10-30.  
  4. ^ "Formulation and Evaluation of Gastroretentive Floating Tablets of Famotidine". Farmavita.Net. 2008. http://www.farmavita.net/content/view/1012/84/. Retrieved 2009-01-30.  
  5. ^ "Pepcid Side Effects & Drug Interactions". RxList.com. 2008. http://www.rxlist.com/cgi/generic/famot_ad.htm. Retrieved 2008-07-31.  

Got something to say? Make a comment.
Your name
Your email address