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Systematic (IUPAC) name
CAS number 76824-35-6
ATC code A02BA03
PubChem 3325
DrugBank APRD00296
Chemical data
Formula C8H15N7O2S3 
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


Pregnancy cat.

B1 (Au), B (U.S.)

Legal status

S3/S4 (Au), POM/OTC (UK),
OTC/℞-only (U.S.)

Routes Oral, IV

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

Clinical use

Main article: H2-receptor antagonist

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.

History and development

Famotidine was developed by Merck & Co.. 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) was 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.

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Famotidine". A list of authors is available in Wikipedia.
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