Famotidine

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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. 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
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 it is commonly used in the treatment of peptic ulcer disease (PUD) and gastroesophageal reflux disease (GERD/GORD). It is commonly marketed by J&J/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]

[edit] History and development

Famotidine was developed by Merck & Co. 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.

[edit] Clinical use

Main article: H2 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.

[edit] Adverse effects

Few adverse drug reactions are associated with famotidine use. In clinical trials, the most common adverse effects were headache, dizziness, and constipation or diarrhea.^[2]

[edit] References