Famotidine, sold under the brand name Pepcid among others, is a histamine H₂ receptor antagonist medication that decreases

stomach acid Gastric acid, gastric juice, or stomach acid is a digestive fluid formed within the stomach lining. With a pH between 1 and 3, gastric acid plays a key role in digestion of proteins by activating digestive enzymes, which together break down the ...

production. It is used to treat

peptic ulcer disease Peptic ulcer disease (PUD) is a break in the inner lining of the stomach, the first part of the small intestine, or sometimes the lower esophagus. An ulcer in the stomach is called a gastric ulcer, while one in the first part of the intestines i ...

gastroesophageal reflux disease Gastroesophageal reflux disease (GERD) or gastro-oesophageal reflux disease (GORD) is one of the upper gastrointestinal chronic diseases where stomach content persistently and regularly flows up into the esophagus, resulting in symptoms and/ ...

, and Zollinger-Ellison syndrome. It is taken

by mouth Oral administration is a route of administration where a substance is taken through the mouth. Per os abbreviated to P.O. is sometimes used as a direction for medication to be taken orally. Many medications are taken orally because they are i ...

or by

injection into a vein Intravenous therapy (abbreviated as IV therapy) is a medical technique that administers fluids, medications and nutrients directly into a person's vein. The intravenous route of administration is commonly used for rehydration or to provide nutrie ...

. It begins working within an hour. Common side effects include headache, intestinal upset, and dizziness. Serious side effects may include

pneumonia Pneumonia is an inflammatory condition of the lung primarily affecting the small air sacs known as alveoli. Symptoms typically include some combination of productive or dry cough, chest pain, fever, and difficulty breathing. The severity ...

and

seizures An epileptic seizure, informally known as a seizure, is a period of symptoms due to abnormally excessive or neural oscillation, synchronous neuronal activity in the brain. Outward effects vary from uncontrolled shaking movements involving much o ...

. Use in

pregnancy Pregnancy is the time during which one or more offspring develops ( gestates) inside a woman's uterus (womb). A multiple pregnancy involves more than one offspring, such as with twins. Pregnancy usually occurs by sexual intercourse, but ca ...

appears safe but has not been well studied while use during

breastfeeding Breastfeeding, or nursing, is the process by which human breast milk is fed to a child. Breast milk may be from the breast, or may be expressed by hand or pumped and fed to the infant. The World Health Organization (WHO) recommends that br ...

is not recommended. Famotidine was patented in 1979 and came into medical use in 1985. It is available as a

generic medication A generic drug is a pharmaceutical drug that contains the same chemical substance as a drug that was originally protected by chemical patents. Generic drugs are allowed for sale after the patents on the original drugs expire. Because the active ch ...

. In 2020, it was the 66th most commonly prescribed medication in the United States, with more than 10million prescriptions.

Medical uses

* Relief of

heartburn Heartburn, also known as pyrosis, cardialgia or acid indigestion, is a burning sensation in the central chest or upper central abdomen. Heartburn is usually due to regurgitation of gastric acid (gastric reflux) into the esophagus. It is the ma ...

, acid indigestion, and sour stomach * Treatment for

gastric The stomach is a muscular, hollow organ in the gastrointestinal tract of humans and many other animals, including several invertebrates. The stomach has a dilated structure and functions as a vital organ in the digestive system. The stomach i ...

and

duodenal ulcers Peptic ulcer disease (PUD) is a break in the inner lining of the stomach, the first part of the small intestine, or sometimes the lower esophagus. An ulcer in the stomach is called a gastric ulcer, while one in the first part of the intestines ...

* Treatment for pathologic gastrointestinal hypersecretory conditions such as

Zollinger–Ellison syndrome Zollinger–Ellison syndrome (Z-E syndrome) is a disease in which tumors cause the stomach to produce too much acid, resulting in peptic ulcers. Symptoms include abdominal pain and diarrhea. The syndrome is caused by a gastrinoma, a neuroendocrin ...

and multiple endocrine adenomas * Treatment for

(GERD) * Treatment for

esophagitis Esophagitis, also spelled oesophagitis, is a disease characterized by inflammation of the esophagus. The esophagus is a tube composed of a mucosal lining, and longitudinal and circular smooth muscle fibers. It connects the pharynx to the stomach; s ...

* Part of a multidrug regimen for ''

Helicobacter pylori ''Helicobacter pylori'', previously known as ''Campylobacter pylori'', is a gram-negative, microaerophilic, spiral (helical) bacterium usually found in the stomach. Its helical shape (from which the genus name, helicobacter, derives) is though ...

'' eradication, although

omeprazole Omeprazole, sold under the brand names Prilosec and Losec, among others, is a medication used in the treatment of gastroesophageal reflux disease (GERD), peptic ulcer disease, and Zollinger–Ellison syndrome. It is also used to prevent upper g ...

may be somewhat more effective. * Prevention of

NSAID Non-steroidal anti-inflammatory drugs (NSAID) are members of a therapeutic drug class which reduces pain, decreases inflammation, decreases fever, and prevents blood clots. Side effects depend on the specific drug, its dose and duration of ...

-induced peptic ulcers. * Given to surgery patients before operations to reduce the risk of

aspiration pneumonitis Aspiration pneumonia is a type of pneumonia, lung infection that is due to a relatively large amount of material from the stomach or mouth entering the lungs. Signs and symptoms often include fever and cough of relatively rapid onset. Complication ...

Pharmacokinetics

Famotidine has a delayed onset of action, beginning after 90 minutes. However, famotidine has a duration of effect of at least . At its peak effect, after administration, famotidine reduces acid secretion by 7.3 mmol per 30 minutes.

Side effects

The most common side effects associated with famotidine use include

headache Headache is the symptom of pain in the face, head, or neck. It can occur as a migraine, tension-type headache, or cluster headache. There is an increased risk of depression in those with severe headaches. Headaches can occur as a result ...

dizziness Dizziness is an imprecise term that can refer to a sense of disorientation in space, vertigo, or lightheadedness. It can also refer to disequilibrium or a non-specific feeling, such as giddiness or foolishness. Dizziness is a common medical c ...

, and

constipation Constipation is a bowel dysfunction that makes bowel movements infrequent or hard to pass. The stool is often hard and dry. Other symptoms may include abdominal pain, bloating, and feeling as if one has not completely passed the bowel movement ...

diarrhea Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin wi ...

. Famotidine may contribute to

QT prolongation Long QT syndrome (LQTS) is a condition affecting repolarization (relaxing) of the heart after a heartbeat, giving rise to an abnormally lengthy QT interval. It results in an increased risk of an irregular heartbeat which can result in fainting, ...

, particularly when used with other QT-elongating drugs, or in people with poor

kidney function Assessment of kidney function occurs in different ways, using the presence of symptoms and signs, as well as measurements using urine tests, blood tests, and medical imaging. Functions of a healthy kidney include maintaining a person's fluid ...

Mechanism of action

Activation of H₂ receptors located on parietal cells stimulates

proton pumps A proton pump is an integral membrane protein pump that builds up a proton gradient across a biological membrane. Proton pumps catalyze the following reaction: : n one side of a biological membrane/sub> + energy n the other side of the membr ...

to secrete acid into the stomach lumen. Famotidine, an H₂ antagonist, blocks the action of

histamine Histamine is an organic nitrogenous compound involved in local immune responses, as well as regulating physiological functions in the gut and acting as a neurotransmitter for the brain, spinal cord, and uterus. Since histamine was discovered in ...

on the parietal cells, ultimately reducing acid secretion into the stomach.

Interactions

Unlike

cimetidine Cimetidine, sold under the brand name Tagamet among others, is a histamine H2 receptor antagonist that inhibits stomach acid production. It is mainly used in the treatment of heartburn and peptic ulcers. The development of longer-acting H2 rec ...

, the first H₂ antagonist, famotidine has a minimal effect on the

cytochrome P450 Cytochromes P450 (CYPs) are a Protein superfamily, superfamily of enzymes containing heme as a cofactor (biochemistry), cofactor that functions as monooxygenases. In mammals, these proteins oxidize steroids, fatty acids, and xenobiotics, and are ...

enzyme system, and does not appear to interact with as many drugs as other medications in its class. Some exceptions include antiretrovirals such as atazanavir, chemotherapeutics such as doxorubicin, and antifungal medications such as itraconazole.

History

Famotidine was developed by

Yamanouchi Pharmaceutical is a Japanese multinational pharmaceutical company, formed on 1 April 2005 from the merger of and . On February 5, 2020, the company announced management changes effective from April 1, 2020. Astellas is a member of the Mitsubishi UFJ Finan ...

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 Imidazole (ImH) is an organic compound with the formula C3N2H4. It is a white or colourless solid that is soluble in water, producing a mildly alkaline solution. In chemistry, it is an aromatic heterocycle, classified as a diazole Diazole refers ...

ring of cimetidine was replaced with a 2-guanidinothiazole ring. Famotidine proved to be nine times more potent than

ranitidine Ranitidine, sold under the brand name Zantac among others, is a medication used to decrease stomach acid production. It is commonly used in treatment of peptic ulcer disease, gastroesophageal reflux disease, and Zollinger–Ellison syndrome. I ...

, and thirty-two times more potent than

. It was first marketed in 1981. Pepcid RPD

orally disintegrating tablet An orally disintegrating tablet or orally dissolving tablet (ODT) is a drug dosage form available for a limited range of over-the-counter (OTC) and prescription medications. ODTs differ from traditional tablets in that they are designed to be d ...

s were released in 1999. Generic preparations became available in 2001, e.g. Fluxid ( Schwarz) or Quamatel (

Gedeon Richter Ltd. Gedeon Richter Plc. is a Hungary, Hungarian Multinational corporation, multinational pharmaceutical industry, pharmaceutical and biotechnology company headquartered in Budapest, Hungary. It is one of the largest companies of the industry in the C ...

). In the United States and Canada, a product called Pepcid Complete, which combines famotidine with an

antacid An antacid is a substance which neutralizes stomach acidity and is used to relieve heartburn, indigestion or an upset stomach. Some antacids have been used in the treatment of constipation and diarrhea. Marketed antacids contain salts of alumi ...

in a chewable tablet to quickly relieve the symptoms of excess stomach acid, is available. In the UK, this product was known as PepcidTwo until its discontinuation in April 2015. Famotidine has poor bioavailibility (50%) due to low gastroretention time. Famotidine is less soluble at higher pH, and when used in combination with antacids gastroretention time is increased. This promotes local delivery of these drugs to receptors in the parietal cell membrane and increases bioavailibility. Researchers are developing tablet formulations that rely on other gastroretentive drug delivery systems such as floating tablets to further increase bioavailibility.

Society and culture

Certain preparations of famotidine are available

over the counter Over-the-counter (OTC) drugs are medicines sold directly to a consumer without a requirement for a prescription from a healthcare professional, as opposed to prescription drugs, which may be supplied only to consumers possessing a valid prescr ...

(OTC) in various countries. In the United States and Canada, 10 mg and 20 mg tablets, sometimes in combination with an

, are available OTC. Larger doses still require a medical prescription. Formulations of famotidine in combination with

ibuprofen Ibuprofen is a nonsteroidal anti-inflammatory drug (NSAID) that is used for treating pain, fever, and inflammation. This includes painful menstrual periods, migraines, and rheumatoid arthritis. It may also be used to close a patent ductus arte ...

were marketed by

Horizon Pharma Horizon Therapeutics Public Ltd Co is a biopharmaceutical company focused on researching, developing, and commercializing medicines that address critical needs for people impacted by rare and rheumatic diseases. Horizon primarily markets products ...

under the trade name Duexis.

Research

COVID-19

At the start of the COVID-19 pandemic, some doctors observed that anecdotally some hospitalized patients on famotidine in China may have had better outcomes than other patients that were not taking famotidine. This led to hypotheses about use of famotidine in treament of COVID-19. Famotidine was researched for potential benefit in treating

COVID-19 Coronavirus disease 2019 (COVID-19) is a contagious disease caused by a virus, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The first known case was COVID-19 pandemic in Hubei, identified in Wuhan, China, in December ...

following hypotheses at the start of the pandemic that it may be an applicable medication. No good evidence of benefit was found.

Veterinary uses

Famotidine is given to dogs and cats with acid reflux. Famotidine has been used in combination with an H₁ antagonist to treat and prevent

urticaria Hives, also known as urticaria, is a kind of skin rash with red, raised, itchy bumps. Hives may burn or sting. The patches of rash may appear on different body parts, with variable duration from minutes to days, and does not leave any long-lasti ...

caused by an acute allergic reaction.

References

External links

* {{Portal bar , Medicine Amidines Guanidines H2 receptor antagonists Sulfamides Thiazoles Thioethers Wikipedia medicine articles ready to translate