Famotidine
Encyclopedia
Famotidine (icon) 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 Johnson & Johnson
/Merck
under the trade names Pepcidine and Pepcid and by Astellas under the trade name Gaster. 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
.
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 1981. 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
.
Famotidine suffers from poor bioavailability
(50%), as it is poorly soluble in the low pH of the stomach. Famotidine used in combination with antacids 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 and thereby improve 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.
(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 postoperative nausea and to reduce the risk of aspiration pneumonitis
. Famotidine is also given to some patients who take NSAIDs, to prevent peptic ulcers. It serves as an alternative to proton-pump inhibitors.
It is also given to dogs with acid reflux.
Famotidine has also been used in combination with an H1 antagonist to treat and prevent urticaria caused by an acute allergic reaction.
It has been found to decrease the debilitating effects of chronic heart failure by blocking histamine
.
s, the most common adverse effects were headache
, dizziness
, and constipation
or diarrhea
.
H2-receptor antagonist
The H2 receptor antagonists are a class of drugs used to block the action of histamine on parietal cells in the stomach, decreasing the production of acid by these cells. H2 antagonists are used in the treatment of dyspepsia, although they have been surpassed in popularity by the more effective ...
that inhibits stomach acid
Gastric acid
Gastric acid is a digestive fluid, formed in the stomach. It has a pH of 1 to 2 and is composed of hydrochloric acid , and large quantities of potassium chloride and sodium chloride...
production, and it is commonly used in the treatment of peptic ulcer
Peptic ulcer
A peptic ulcer, also known as PUD or peptic ulcer disease, is the most common ulcer of an area of the gastrointestinal tract that is usually acidic and thus extremely painful. It is defined as mucosal erosions equal to or greater than 0.5 cm...
disease (PUD) and gastroesophageal reflux disease (GERD/GORD). It is commonly marketed by Johnson & Johnson
Johnson & Johnson
Johnson & Johnson is an American multinational pharmaceutical, medical devices and consumer packaged goods manufacturer founded in 1886. Its common stock is a component of the Dow Jones Industrial Average and the company is listed among the Fortune 500....
/Merck
Merck & Co.
Merck & Co., Inc. , also known as Merck Sharp & Dohme or MSD outside the United States and Canada, is one of the largest pharmaceutical companies in the world. The Merck headquarters is located in Whitehouse Station, New Jersey, an unincorporated area in Readington Township...
under the trade names Pepcidine and Pepcid and by Astellas under the trade name Gaster. Unlike cimetidine
Cimetidine
Cimetidine INN is a histamine H2-receptor antagonist that inhibits the production of acid in the stomach. It is largely used in the treatment of heartburn and peptic ulcers. It is marketed by GlaxoSmithKline under the trade name Tagamet...
, the first H2 antagonist, famotidine has no effect on the cytochrome P450 enzyme system, and does not appear to interact with other drugs
Drug interaction
A drug interaction is a situation in which a substance affects the activity of a drug, i.e. the effects are increased or decreased, or they produce a new effect that neither produces on its own. Typically, interaction between drugs come to mind...
.
History and development
Famotidine was developed by Yamanouchi Pharmaceutical Co. It was licensed in the mid-80s by Merck & Co.Merck & Co.
Merck & Co., Inc. , also known as Merck Sharp & Dohme or MSD outside the United States and Canada, is one of the largest pharmaceutical companies in the world. The Merck headquarters is located in Whitehouse Station, New Jersey, an unincorporated area in Readington Township...
and is marketed by a joint venture between Merck and Johnson & Johnson
Johnson & Johnson
Johnson & Johnson is an American multinational pharmaceutical, medical devices and consumer packaged goods manufacturer founded in 1886. Its common stock is a component of the Dow Jones Industrial Average and the company is listed among the Fortune 500....
. The imidazole
Imidazole
Imidazole is an organic compound with the formula C3H4N2. This aromatic heterocyclic is a diazole and is classified as an alkaloid. Imidazole refers to the parent compound, whereas imidazoles are a class of heterocycles with similar ring structure, but varying substituents...
-ring of cimetidine
Cimetidine
Cimetidine INN is a histamine H2-receptor antagonist that inhibits the production of acid in the stomach. It is largely used in the treatment of heartburn and peptic ulcers. It is marketed by GlaxoSmithKline under the trade name Tagamet...
was replaced with a 2-guanidinothiazole ring. Famotidine proved to be 30 times more active than cimetidine
Cimetidine
Cimetidine INN is a histamine H2-receptor antagonist that inhibits the production of acid in the stomach. It is largely used in the treatment of heartburn and peptic ulcers. It is marketed by GlaxoSmithKline under the trade name Tagamet...
.
It was first marketed in 1981. Pepcid RPD orally-disintegrating tablets
Orally disintegrating tablet
An orally disintegrating tablet or orodispersible tablet is a drug dosage form available for a limited amount of over-the-counter and prescription medications. ODTs differ from traditional tablets in that they are designed to be dissolved on the tongue rather than swallowed whole...
(that are not swallowed) were released in 1999. Generic preparations became available in 2001, e.g. Fluxid (Schwarz) or Quamatel (Gedeon Richter Ltd.
Gedeon Richter Ltd.
Gedeon Richter Plc. , the largest pharmaceutical factory in Hungary, was established by Mr. Gedeon Richter, a pharmacist in 1901. Mr. Richter is not only the founder of the company, but the establishment of his firm also marked the beginning of the development of the Hungarian pharmaceutical industry...
).
In the United States, a product called Pepcid Complete
Pepcid Complete
Pepcid AC, Acid controller comarketed by Johnson & Johnson and Merck, is a combination of the H2-blocker famotidine with the antacids calcium carbonate and magnesium hydroxide...
is available that combines famotidine with an antacid
Antacid
An antacid is a substance which neutralizes stomach acidity.-Mechanism of action:Antacids perform a neutralization reaction, increasing the pH to reduce acidity in the stomach. When gastric hydrochloric acid reaches the nerves in the gastrointestinal mucosa, they signal pain to the central nervous...
in a chewable tablet to ameliorate the relatively slow onset of effects. In the UK, this product is known as Pepcidtwo
Pepcid Complete
Pepcid AC, Acid controller comarketed by Johnson & Johnson and Merck, is a combination of the H2-blocker famotidine with the antacids calcium carbonate and magnesium hydroxide...
.
Famotidine suffers from poor bioavailability
Bioavailability
In pharmacology, bioavailability is a subcategory of absorption and is used to describe the fraction of an administered dose of unchanged drug that reaches the systemic circulation, one of the principal pharmacokinetic properties of drugs. By definition, when a medication is administered...
(50%), as it is poorly soluble in the low pH of the stomach. Famotidine used in combination with antacids 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 and thereby improve 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.
Clinical use
Certain preparations of famotidine are available over the counterOver-the-counter drug
Over-the-counter drugs are medicines that may be sold directly to a consumer without a prescription from a healthcare professional, as compared to prescription drugs, which may be sold only to consumers possessing a valid prescription...
(OTC) in various countries. In the United States, preparations of 10 mg and 20 mg tablets, sometimes in combination with a more traditional antacid
Antacid
An antacid is a substance which neutralizes stomach acidity.-Mechanism of action:Antacids perform a neutralization reaction, increasing the pH to reduce acidity in the stomach. When gastric hydrochloric acid reaches the nerves in the gastrointestinal mucosa, they signal pain to the central nervous...
, are available OTC. Larger doses still require a prescription.
Famotidine is given to surgery patients before operations to prevent postoperative nausea and to reduce the risk of aspiration pneumonitis
Aspiration pneumonia
Aspiration pneumonia is bronchopneumonia that develops due to the entrance of foreign materials into the bronchial tree, usually oral or gastric contents...
. Famotidine is also given to some patients who take NSAIDs, to prevent peptic ulcers. It serves as an alternative to proton-pump inhibitors.
It is also given to dogs with acid reflux.
Famotidine has also been used in combination with an H1 antagonist to treat and prevent urticaria caused by an acute allergic reaction.
It has been found to decrease the debilitating effects of chronic heart failure by blocking histamine
Histamine
Histamine is an organic nitrogen compound involved in local immune responses as well as regulating physiological function in the gut and acting as a neurotransmitter. Histamine triggers the inflammatory response. As part of an immune response to foreign pathogens, histamine is produced by...
.
Side effects
Side effects are associated with famotidine use. In clinical trialClinical trial
Clinical trials are a set of procedures in medical research and drug development that are conducted to allow safety and efficacy data to be collected for health interventions...
s, the most common adverse effects were headache
Headache
A headache or cephalalgia is pain anywhere in the region of the head or neck. It can be a symptom of a number of different conditions of the head and neck. The brain tissue itself is not sensitive to pain because it lacks pain receptors. Rather, the pain is caused by disturbance of the...
, dizziness
Dizziness
Dizziness refers to an impairment in spatial perception and stability. The term is somewhat imprecise. It can be used to mean vertigo, presyncope, disequilibrium, or a non-specific feeling such as giddiness or foolishness....
, and constipation
Constipation
Constipation refers to bowel movements that are infrequent or hard to pass. Constipation is a common cause of painful defecation...
or diarrhea
Diarrhea
Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...
.