Famotidine
3-[2-(diaminomethyleneamino)thiazol- 4-ylmethylthio]-N-sulfamoylpropionamidine
CAS number 76824-35-6	ATC code
Chemical formula	C8H15N7O2S3
Molecular weight	337.5
Bioavailability	40-45%
Metabolism	hepatic
Elimination half-life	2-3.5 hours
Excretion	renal
Pregnancy category	B1 (Australia)
Legal status	Schedule 4 (Aust) POM (UK)
Routes of administration	oral

Famotidine 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). It was developed and marketed by Merck & Co. under the trade names Pepcidine and Pepcid.

Clinical use

Main article: H2-receptor antagonist

History and development

Famotidine was developed by Merck & Co., and was first marketed in 1985. The imidazole-ring of cimetidine was replaced with a 2-guanidinothiazole ring. Famotidine proved to be 30 times more active than cimetidine.