Article: Famotidine

Famotidine
Systematic (IUPAC) name
2-[4-[2-(amino-sulfamoylimino-methyl) ethylsulfanylmethyl]-1,3-thiazol-2-yl]guanidine
Identifiers
CAS number	76824-35-6
ATC code	A02BA03
PubChem	3325
DrugBank	APRD00296
Chemical data
Formula	C8H15N7O2S3
Mol. weight	337.449 g/mol
Pharmacokinetic data
Bioavailability	20–66%
Protein binding	10–28%
Metabolism	Hepatic
Half life	2.6–4 hours
Excretion	Renal 20–70%, faecal 50%
Therapeutic considerations
Pregnancy cat.	B1 (Au), B (U.S.)
Legal status	S3/S4 (Au), POM (UK), OTC/℞-only (U.S.)
Routes	Oral, IV

Famotidine (INN) (IPA: [fəˈmɒtɪdin]) 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.

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). 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.

Off label use

Some Asians use famotidine to mitigate the alcohol flush reaction or Asian flush. The mechanism by which famotidine lessens the reddening is not currently understood.