|Trade names||Pepcid, others|
|Oral (tablets), Intravenous|
|Elimination half-life||2.5–3.5 hours|
|Excretion||Renal (25-30% unchanged [Oral])|
|CompTox Dashboard (EPA)|
|Chemical and physical data|
|Molar mass||337.449 g/mol g·mol−1|
|3D model (JSmol)|
Famotidine, sold under the trade name Pepcid among others, is a medication that decreases stomach acid production. It is used to treat peptic ulcer disease, gastroesophageal reflux disease, and Zollinger-Ellison syndrome. It is taken by mouth or by injection into a vein. It begins working within an hour.
Common side effects include headache, intestinal upset, and dizziness. Serious side effects may include pneumonia and seizures. Use in pregnancy appears safe but has not been well studied while use during breastfeeding is not recommended. It is a histamine H2 receptor antagonist.
Famotidine was patented in 1979 and came into medical use in 1985. It is available as a generic medication. A month supply in the United Kingdom costs the NHS about 30 ₤ as of 2019. In the United States the wholesale cost of this amount is about 2 USD. In 2016 it was the 125th most prescribed medication in the United States with more than 5 million prescriptions.
- Relief of heartburn, acid indigestion, and sour stomach
- Treatment for gastric and duodenal ulcers
- Treatment for pathologic gastrointestinal hypersecretory conditions such as Zollinger–Ellison syndrome and multiple endocrine adenomas
- Treatment for gastroesophageal reflux disease (GERD)
- Treatment for esophagitis
- Part of a multidrug regimen for Helicobacter pylori eradication, although omeprazole may be somewhat more effective.
- Prevention of NSAID-induced peptic ulcers.
- Given to surgery patients before operations to reduce the risk of aspiration pneumonitis.
Mechanism of action
Famotidine blocks the action of histamine in the stomach cell and ultimately block acid secretion in the stomach, as a result, less amount of acid production.
Famotidine was developed by Yamanouchi Pharmaceutical Co. It was licensed in the mid-1980s 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 nine times more potent than ranitidine, and thirty-two times more potent than cimetidine.
In the United States and Canada, a product called Pepcid Complete, which combines famotidine with an antacid in a chewable tablet to quickly relieve the symptoms of excess stomach acid, is available. In the UK, this product was known as Pepcidtwo prior to its discontinuation in April 2015.
Famotidine suffers from poor bioavailability (50%), as it is poorly soluble in the low pH of the stomach. When used in combination with antacids, it promotes local delivery of these drugs to the receptor of the parietal cell wall. Therefore, researchers are developing innovative formulations of tablets, such as gastroretentive drug delivery systems. Such tablets are retained in the stomach for a longer period of time, thereby improving 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.
Certain preparations of famotidine are available over the counter (OTC) in various countries. In the United States and Canada, 10 mg and 20 mg tablets, sometimes in combination with an antacid, are available OTC. Larger doses still require a medical prescription.
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- Pepcid Complete
- Drugs.com duexis