Famotidine

Famotidine

Clinical data
Pronunciation	/fəˈmɒtɪdiːn/
Trade names	Pepcid, Zantac 360, others
AHFS/Drugs.com	Monograph
MedlinePlus	a687011
License data	US DailyMed: Famotidine
Pregnancy category	AU: B1
intravenous
ATC code	A02BA03 (WHO)
Legal status
Legal status	AU: S3 (Pharmacist only) / S4 UK: General sales list (GSL, OTC) US: OTC /Rx-only[1][2]
Pharmacokinetic data
Bioavailability	40–45% (by mouth)[1]
Protein binding	15–20%[1]
Elimination half-life	2.5–3.5 hours[1]
Excretion	Kidney (25–30% unchanged [Oral])[1]
Identifiers
IUPAC name 3-[({2-[(diaminomethylidene)amino]-1,3-thiazol-4-yl}methyl)sulfanyl]-N-sulfamoylpropanimidamide
JSmol)	Interactive image
SMILES NS(=O)(=O)/N=C(\N)CCSCc1csc(n1)N=C(N)N
InChI InChI=1S/C8H15N7O2S3/c9-6(15-20(12,16)17)1-2-18-3-5-4-19-8(13-5)14-7(10)11/h4H,1-3H2,(H2,9,15)(H2,12,16,17)(H4,10,11,13,14) Y Key:XUFQPHANEAPEMJ-UHFFFAOYSA-N Y
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Famotidine, sold under the brand name Pepcid among others, is a

• Relief of heartburn, acid indigestion, and sour stomach
• Treatment for
  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.^{[9][10][11][12][13][14]}
• Prevention of NSAID-induced peptic ulcers.^[15][16]
• Given to surgery patients before operations to reduce the risk of aspiration pneumonitis.^[17][18][19]

Pharmacokinetics

Famotidine has a delayed onset of action, beginning after 90 minutes. However, famotidine has a duration of effect of at least 540 minutes (9.0 h). At its peak effect, 210 minutes (3.5 h) after administration, famotidine reduces acid secretion by 7.3 mmol per 30 minutes.^[20]

Side effects

The most common side effects associated with famotidine use include headache, dizziness, and constipation or diarrhea.^[21][22]

Famotidine may contribute to

Unlike cimetidine, the first H₂ antagonist, famotidine has a minimal effect on the cytochrome P450 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. ^[25][26][27]

History

Famotidine was developed by

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.^[32]

Society and culture

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,^[33][34] are available OTC. Larger doses still require a prescription.

Formulations of famotidine in combination with

Small-scale studies have shown inconsistent and inconclusive evidence of efficacy in treatment-refractory schizophrenia.^[43]

Veterinary uses

Famotidine is given to dogs and cats with acid reflux.^[44]

References