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{{Short description|Medication that reduces stomach acid}}
{{Short description|Medication that reduces stomach acid}}
{{Use dmy dates|date=July 2024}}
{{Redirect|Cepal|the international organization|United Nations Economic Commission for Latin America and the Caribbean}}
{{cs1 config|name-list-style=vanc|display-authors=6}}
{{Use dmy dates|date=October 2022}}
{{Infobox drug
{{Infobox drug
| Watchedfields = changed
| Watchedfields = changed
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| image2 = File:Famotidine-from-xtal-Mercury-3D-bs.png
| image2 = File:Famotidine-from-xtal-Mercury-3D-bs.png
| alt2 =
| alt2 =
| caption =
| caption = <!-- Clinical data -->

<!-- Clinical data -->
| pronounce = {{IPAc-en|f|ə|ˈ|m|ɒ|t|ɪ|d|iː|n}}
| pronounce = {{IPAc-en|f|ə|ˈ|m|ɒ|t|ɪ|d|iː|n}}
| tradename = Pepcid, Zantac 360, others
| tradename = Pepcid, Zantac 360, others
| Drugs.com = {{drugs.com|monograph|famotidine}}
| Drugs.com = {{drugs.com|monograph|famotidine}}
| MedlinePlus = a687011
| MedlinePlus = a687011
| licence_EU = <!-- EMA uses INN (or special INN_EMA) -->
| DailyMedID = Famotidine
| DailyMedID = Famotidine
| licence_US =
| pregnancy_AU = B1
| pregnancy_AU = B1
| pregnancy_AU_comment =
| pregnancy_AU_comment = <ref name=Preg2019 />
| pregnancy_category=
| pregnancy_category =
| routes_of_administration = [[Oral administration|By mouth]], [[intravenous]]
| routes_of_administration = [[Oral administration|By mouth]], [[intravenous]]
| class = [[H2 receptor antagonist|Histamine H<sub>2</sub> receptor antagonist]]
| class =
| ATCvet =
| ATC_prefix = A02
| ATC_prefix = A02
| ATC_suffix = BA03
| ATC_suffix = BA03
| ATC_supplemental =
| ATC_supplemental = <!-- Legal status -->

<!-- Legal status -->
| legal_AU = S3
| legal_AU = S3
| legal_AU_comment = /&nbsp;S4
| legal_AU_comment = /&nbsp;S4
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| legal_UK_comment =
| legal_UK_comment =
| legal_US = OTC
| legal_US = OTC
| legal_US_comment = /Rx-only<ref name="Famotidine FDA label">{{cite web | title=Famotidine tablet | website=DailyMed | url=https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=f149ecc1-d66c-42f9-a3f4-2ab6a522942b | access-date=6 March 2021 | archive-date=14 July 2017 | archive-url=https://web.archive.org/web/20170714005606/https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=f149ecc1-d66c-42f9-a3f4-2ab6a522942b | url-status=live }}</ref><ref>{{cite web | title=Zantac 360- famotidine tablet, film coated | website=DailyMed | date=17 May 2022 | url=https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=89f60eb1-359b-40e8-ae8b-65aec9cd5b1f | access-date=6 July 2022 | archive-date=6 July 2022 | archive-url=https://web.archive.org/web/20220706044019/https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=89f60eb1-359b-40e8-ae8b-65aec9cd5b1f | url-status=live }}</ref>
| legal_US_comment = /{{nbsp}}Rx-only<ref name="Famotidine FDA label">{{cite web | title=Famotidine tablet | website=DailyMed | url=https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=f149ecc1-d66c-42f9-a3f4-2ab6a522942b | access-date=6 March 2021 | archive-date=31 March 2024 | archive-url=https://web.archive.org/web/20240331041550/https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=f149ecc1-d66c-42f9-a3f4-2ab6a522942b | url-status=live }}</ref><ref name="DailyMed-2022-Zantac-360">{{cite web | title=Zantac 360- famotidine tablet, film coated | website=DailyMed | date=17 May 2022 | url=https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=89f60eb1-359b-40e8-ae8b-65aec9cd5b1f | access-date=6 July 2022 | archive-date=6 July 2022 | archive-url=https://web.archive.org/web/20220706044019/https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=89f60eb1-359b-40e8-ae8b-65aec9cd5b1f | url-status=live }}</ref>
| legal_EU =
| legal_EU =
| legal_EU_comment =
| legal_EU_comment =
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| legal_status = <!-- For countries not listed above -->
| legal_status = <!-- For countries not listed above -->


<!-- Pharmacokinetic data -->
<!-- Pharmacokinetic data -->| bioavailability = 40–45% (by mouth)<ref name="Famotidine FDA label" />
| bioavailability = 40–45% (by mouth)<ref name="Famotidine FDA label" />
| protein_bound = 15–20%<ref name="Famotidine FDA label" />
| protein_bound = 15–20%<ref name="Famotidine FDA label" />
| metabolism =
| metabolism =
| metabolites =
| metabolites =
| onset =
| onset = 90 minutes
| elimination_half-life = 2.5–3.5 hours<ref name="Famotidine FDA label" />
| elimination_half-life = 2.5–3.5 hours<ref name="Famotidine FDA label" />
| duration_of_action =
| duration_of_action = 9 hours
| excretion = [[Kidney]] (25–30% unchanged [Oral])<ref name="Famotidine FDA label" />
| excretion = [[Kidney]] (25–30% unchanged [Oral])<ref name="Famotidine FDA label" />


<!-- Identifiers -->
<!-- Identifiers -->| CAS_number_Ref = {{cascite|correct|??}}
| CAS_number_Ref = {{cascite|correct|??}}
| CAS_number = 76824-35-6
| CAS_number = 76824-35-6
| CAS_supplemental =
| CAS_supplemental =
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| NIAID_ChemDB =
| NIAID_ChemDB =
| PDB_ligand = FO9
| PDB_ligand = FO9
| synonyms =
| synonyms = <!-- Chemical and physical data -->

<!-- Chemical and physical data -->
| IUPAC_name = 3-[({2-[(diaminomethylidene)amino]-1,3-thiazol-4-yl}methyl)sulfanyl]-''N''-sulfamoylpropanimidamide
| IUPAC_name = 3-[({2-[(diaminomethylidene)amino]-1,3-thiazol-4-yl}methyl)sulfanyl]-''N''-sulfamoylpropanimidamide
| C = 8
| C=8 | H=15 | N=7 | O=2 | S=3
| H = 15
| N = 7
| O = 2
| S = 3
| SMILES = NS(=O)(=O)/N=C(\N)CCSCc1csc(n1)N=C(N)N
| SMILES = NS(=O)(=O)/N=C(\N)CCSCc1csc(n1)N=C(N)N
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
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<!-- Definition and medical uses -->
<!-- Definition and medical uses -->
'''Famotidine''', sold under the brand name '''Pepcid''' among others, is a [[H2 antagonist|histamine H<sub>2</sub> receptor antagonist]] medication that decreases [[gastric acid|stomach acid]] production.<ref name="AHFS2019">{{cite web |title=Famotidine Monograph for Professionals |url=https://www.drugs.com/monograph/famotidine.html |access-date=3 March 2019 |website=Drugs.com |publisher=American Society of Health-System Pharmacists |language=en |archive-date=17 June 2019 |archive-url=https://web.archive.org/web/20190617034316/https://www.drugs.com/monograph/famotidine.html |url-status=live }}</ref> It is used to treat [[peptic ulcer disease]], [[gastroesophageal reflux disease]], and [[Zollinger-Ellison syndrome]].<ref name=AHFS2019/> It is taken [[Oral administration|by mouth]] or by [[intravenous|injection into a vein]].<ref name=AHFS2019/> It begins working within an hour.<ref name=AHFS2019/>
'''Famotidine''', sold under the brand name '''Pepcid''' among others, is a [[H2 antagonist|histamine H<sub>2</sub> receptor antagonist]] medication that decreases [[gastric acid|stomach acid]] production.<ref name="AHFS2019">{{cite web |title=Famotidine Monograph for Professionals |url=https://www.drugs.com/monograph/famotidine.html |access-date=3 March 2019 |website=Drugs.com |publisher=American Society of Health-System Pharmacists |archive-date=17 June 2019 |archive-url=https://web.archive.org/web/20190617034316/https://www.drugs.com/monograph/famotidine.html |url-status=live }}</ref> It is used to treat [[peptic ulcer disease]], [[gastroesophageal reflux disease]], and [[Zollinger-Ellison syndrome]].<ref name=AHFS2019/> It is taken [[Oral administration|by mouth]] or by [[intravenous|injection into a vein]].<ref name=AHFS2019/> It begins working within an hour.<ref name=AHFS2019/>


<!-- Side effects and mechanisms -->
<!-- Side effects and mechanisms -->
Common side effects include headache, intestinal upset, and dizziness.<ref name=AHFS2019/> Serious side effects may include [[pneumonia]] and [[seizures]].<ref name=AHFS2019/><ref name=BNF76/> Use in [[pregnancy]] appears safe but has not been well studied while use during [[breastfeeding]] is not recommended.<ref name=Preg2019>{{cite web |title=Famotidine Use During Pregnancy |url=https://www.drugs.com/pregnancy/famotidine.html |website=Drugs.com |access-date=3 March 2019 |language=en |archive-date=9 February 2018 |archive-url=https://web.archive.org/web/20180209015950/https://www.drugs.com/pregnancy/famotidine.html |url-status=live }}</ref>
Common side effects include [[headache]], [[abdominal pain]], [[diarrhea]] or [[constipation]], and [[dizziness]].<ref name=AHFS2019/> Serious side effects may include [[pneumonia]] and [[seizures]].<ref name=AHFS2019/><ref name=BNF76/> Use in [[pregnancy]] appears safe but has not been well studied, while use during [[breastfeeding]] is not recommended.<ref name=Preg2019>{{cite web |title=Famotidine Pregnancy and Breastfeeding Warnings |url=https://www.drugs.com/pregnancy/famotidine.html |website=Drugs.com |access-date=3 March 2019 |archive-date=16 December 2023 |archive-url=https://web.archive.org/web/20231216171826/https://www.drugs.com/pregnancy/famotidine.html |url-status=live }}</ref>


<!-- History and culture -->
<!-- History and culture -->
Famotidine was patented in 1979 and came into medical use in 1985.<ref>{{cite book |vauthors=Fischer J, Ganellin CR |title=Analogue-based Drug Discovery |date=2006 |publisher=John Wiley & Sons |isbn=9783527607495 |page=444 |url=https://books.google.com/books?id=FjKfqkaKkAAC&pg=PA444 |language=en |access-date=7 May 2020 |archive-date=29 July 2020 |archive-url=https://web.archive.org/web/20200729131140/https://books.google.com/books?id=FjKfqkaKkAAC&pg=PA444 |url-status=live }}</ref> It is available as a [[generic medication]].<ref name=BNF76>{{cite book|title=British national formulary : BNF 76|date=2018|publisher=Pharmaceutical Press|isbn=9780857113382|pages=74–75|edition=76}}</ref> In 2020, it was the 66th most commonly prescribed medication in the United States, with more than 10{{nbsp}}million prescriptions.<ref>{{cite web | title = The Top 300 of 2020 | url = https://clincalc.com/DrugStats/Top300Drugs.aspx | website = ClinCalc | access-date = 7 October 2022 }}</ref><ref>{{cite web | title = Famotidine - Drug Usage Statistics | website = ClinCalc | url = https://clincalc.com/DrugStats/Drugs/Famotidine | access-date = 7 October 2022 }}</ref>
Famotidine was patented in 1979 and came into medical use in 1985.<ref name="Fischer-2006">{{cite book |vauthors=Fischer J, Ganellin CR |title=Analogue-based Drug Discovery |date=2006 |publisher=John Wiley & Sons |isbn=9783527607495 |page=444 |url=https://books.google.com/books?id=FjKfqkaKkAAC&pg=PA444 |access-date=7 May 2020 |archive-date=29 July 2020 |archive-url=https://web.archive.org/web/20200729131140/https://books.google.com/books?id=FjKfqkaKkAAC&pg=PA444 |url-status=live }}</ref> It is available as a [[generic medication]].<ref name=BNF76>{{cite book|title=British national formulary : BNF 76|date=2018|publisher=Pharmaceutical Press|isbn=9780857113382|pages=74–75|edition=76}}</ref> In 2022, it was the 49th most commonly prescribed medication in the United States, with more than 13{{nbsp}}million prescriptions.<ref>{{cite web | title=The Top 300 of 2022 | url=https://clincalc.com/DrugStats/Top300Drugs.aspx | website=ClinCalc | access-date=30 August 2024 | archive-date=30 August 2024 | archive-url=https://web.archive.org/web/20240830202410/https://clincalc.com/DrugStats/Top300Drugs.aspx | url-status=live }}</ref><ref>{{cite web | title = Famotidine Drug Usage Statistics, United States, 2013 - 2022 | website = ClinCalc | url = https://clincalc.com/DrugStats/Drugs/Famotidine | access-date = 30 August 2024 | archive-date = 17 April 2020 | archive-url = https://web.archive.org/web/20200417044432/https://clincalc.com/DrugStats/Drugs/Famotidine | url-status = live }}</ref>


== Medical uses ==
== Medical uses ==
* Relief of [[heartburn]], acid indigestion, and sour stomach
*[[Heartburn]], acid indigestion, and sour stomach
* Treatment for [[gastric ulcers|gastric]] and [[duodenal ulcers]]
* Treatment for [[gastric ulcers|gastric]] and [[duodenal ulcers]]
* Treatment for pathologic gastrointestinal hypersecretory conditions such as [[Zollinger–Ellison syndrome]] and [[Multiple endocrine neoplasia|multiple endocrine adenomas]]
* Treatment for pathologic gastrointestinal hypersecretory conditions such as [[Zollinger–Ellison syndrome]] and [[Multiple endocrine neoplasia|multiple endocrine adenomas]]
* Treatment for [[gastroesophageal reflux disease]] (GERD)
* Treatment for [[gastroesophageal reflux disease]] (GERD)
* Treatment for [[esophagitis]]
* Treatment for [[esophagitis]]
* Part of a multidrug regimen for ''[[Helicobacter pylori]]'' eradication, although [[omeprazole]] may be somewhat more effective.<ref>{{cite journal | vauthors = Kanayama S | title = [Proton-pump inhibitors versus H2-receptor antagonists in triple therapy for Helicobacter pylori eradication] | journal = Nihon Rinsho. Japanese Journal of Clinical Medicine | volume = 57 | issue = 1 | pages = 153–6 | date = January 1999 | pmid = 10036954 }}</ref><ref>{{cite journal | vauthors = Soga T, Matsuura M, Kodama Y, Fujita T, Sekimoto I, Nishimura K, Yoshida S, Kutsumi H, Fujimoto S | display-authors = 6 | title = Is a proton pump inhibitor necessary for the treatment of lower-grade reflux esophagitis? | journal = Journal of Gastroenterology | volume = 34 | issue = 4 | pages = 435–40 | date = August 1999 | pmid = 10452673 | doi = 10.1007/s005350050292 | s2cid = 22115962 }}</ref><ref>{{cite journal | vauthors = Borody TJ, Andrews P, Fracchia G, Brandl S, Shortis NP, Bae H | title = Omeprazole enhances efficacy of triple therapy in eradicating Helicobacter pylori | journal = Gut | volume = 37 | issue = 4 | pages = 477–81 | date = October 1995 | pmid = 7489931 | pmc = 1382896 | doi = 10.1136/gut.37.4.477 }}</ref><ref>{{cite journal | vauthors = Hu FL, Jia JC, Li YL, Yang GB | title = Comparison of H2-receptor antagonist- and proton-pump inhibitor-based triple regimens for the eradication of Helicobacter pylori in Chinese patients with gastritis or peptic ulcer | journal = The Journal of International Medical Research | volume = 31 | issue = 6 | pages = 469–74 | date = 2003 | pmid = 14708410 | doi = 10.1177/147323000303100601 | s2cid = 25818901 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Kirika NV, Bodrug NI, Butorov IV, Butorov SI | title = [Efficacy of different schemes of anti-helicobacter therapy in duodenal ulcer] | journal = Terapevticheskii Arkhiv | volume = 76 | issue = 2 | pages = 18–22 | date = 2004 | pmid = 15106408 }}</ref><ref>{{cite journal | vauthors = Fujiwara Y, Higuchi K, Nebiki H, Chono S, Uno H, Kitada K, Satoh H, Nakagawa K, Kobayashi K, Tominaga K, Watanabe T, Oshitani N, Arakawa T | display-authors = 6 | title = Famotidine vs. omeprazole: a prospective randomized multicentre trial to determine efficacy in non-erosive gastro-oesophageal reflux disease | journal = Alimentary Pharmacology & Therapeutics | volume = 21 | issue = Suppl 2 | pages = 10–8 | date = June 2005 | pmid = 15943841 | doi = 10.1111/j.1365-2036.2005.02468.x | s2cid = 24690061 | doi-access = free }}</ref>
* Part of a multidrug regimen for ''[[Helicobacter pylori]]'' eradication, although [[omeprazole]] may be somewhat more effective.<ref name="pmid10036954">{{cite journal | vauthors = Kanayama S | title = [Proton-pump inhibitors versus H2-receptor antagonists in triple therapy for Helicobacter pylori eradication] | journal = Nihon Rinsho. Japanese Journal of Clinical Medicine | volume = 57 | issue = 1 | pages = 153–6 | date = January 1999 | pmid = 10036954 }}</ref><ref name="pmid10452673">{{cite journal | vauthors = Soga T, Matsuura M, Kodama Y, Fujita T, Sekimoto I, Nishimura K, Yoshida S, Kutsumi H, Fujimoto S | title = Is a proton pump inhibitor necessary for the treatment of lower-grade reflux esophagitis? | journal = Journal of Gastroenterology | volume = 34 | issue = 4 | pages = 435–40 | date = August 1999 | pmid = 10452673 | doi = 10.1007/s005350050292 | s2cid = 22115962 }}</ref><ref name="pmid7489931">{{cite journal | vauthors = Borody TJ, Andrews P, Fracchia G, Brandl S, Shortis NP, Bae H | title = Omeprazole enhances efficacy of triple therapy in eradicating Helicobacter pylori | journal = Gut | volume = 37 | issue = 4 | pages = 477–81 | date = October 1995 | pmid = 7489931 | pmc = 1382896 | doi = 10.1136/gut.37.4.477 }}</ref><ref name="pmid14708410">{{cite journal | vauthors = Hu FL, Jia JC, Li YL, Yang GB | title = Comparison of H2-receptor antagonist- and proton-pump inhibitor-based triple regimens for the eradication of Helicobacter pylori in Chinese patients with gastritis or peptic ulcer | journal = The Journal of International Medical Research | volume = 31 | issue = 6 | pages = 469–74 | date = 2003 | pmid = 14708410 | doi = 10.1177/147323000303100601 | s2cid = 25818901 | doi-access = free }}</ref><ref name="pmid15106408">{{cite journal | vauthors = Kirika NV, Bodrug NI, Butorov IV, Butorov SI | title = [Efficacy of different schemes of anti-helicobacter therapy in duodenal ulcer] | journal = Terapevticheskii Arkhiv | volume = 76 | issue = 2 | pages = 18–22 | date = 2004 | pmid = 15106408 }}</ref><ref name="pmid15943841">{{cite journal | vauthors = Fujiwara Y, Higuchi K, Nebiki H, Chono S, Uno H, Kitada K, Satoh H, Nakagawa K, Kobayashi K, Tominaga K, Watanabe T, Oshitani N, Arakawa T | title = Famotidine vs. omeprazole: a prospective randomized multicentre trial to determine efficacy in non-erosive gastro-oesophageal reflux disease | journal = Alimentary Pharmacology & Therapeutics | volume = 21 | issue = Suppl 2 | pages = 10–8 | date = June 2005 | pmid = 15943841 | doi = 10.1111/j.1365-2036.2005.02468.x | s2cid = 24690061 | doi-access = free }}</ref>
* Prevention of [[Nonsteroidal anti-inflammatory drug|NSAID]]-induced peptic ulcers.<ref>{{cite journal | vauthors = La Corte R, Caselli M, Castellino G, Bajocchi G, Trotta F | title = Prophylaxis and treatment of NSAID-induced gastroduodenal disorders | journal = Drug Safety | volume = 20 | issue = 6 | pages = 527–43 | date = June 1999 | pmid = 10392669 | doi = 10.2165/00002018-199920060-00006 | s2cid = 41990751 }}</ref><ref>{{cite journal | vauthors = Laine L, Kivitz AJ, Bello AE, Grahn AY, Schiff MH, Taha AS | title = Double-blind randomized trials of single-tablet ibuprofen/high-dose famotidine vs. ibuprofen alone for reduction of gastric and duodenal ulcers | journal = The American Journal of Gastroenterology | volume = 107 | issue = 3 | pages = 379–86 | date = March 2012 | pmid = 22186979 | pmc = 3321505 | doi = 10.1038/ajg.2011.443 }}</ref>
* Prevention of [[Nonsteroidal anti-inflammatory drug|NSAID]]-induced peptic ulcers.<ref name="pmid10392669">{{cite journal | vauthors = La Corte R, Caselli M, Castellino G, Bajocchi G, Trotta F | title = Prophylaxis and treatment of NSAID-induced gastroduodenal disorders | journal = Drug Safety | volume = 20 | issue = 6 | pages = 527–43 | date = June 1999 | pmid = 10392669 | doi = 10.2165/00002018-199920060-00006 | s2cid = 41990751 }}</ref><ref name="pmid22186979">{{cite journal | vauthors = Laine L, Kivitz AJ, Bello AE, Grahn AY, Schiff MH, Taha AS | title = Double-blind randomized trials of single-tablet ibuprofen/high-dose famotidine vs. ibuprofen alone for reduction of gastric and duodenal ulcers | journal = The American Journal of Gastroenterology | volume = 107 | issue = 3 | pages = 379–86 | date = March 2012 | pmid = 22186979 | pmc = 3321505 | doi = 10.1038/ajg.2011.443 }}</ref>
* Given to surgery patients before operations to reduce the risk of [[Aspiration pneumonia|aspiration pneumonitis]].<ref>{{cite journal | vauthors = Escolano F, Castaño J, López R, Bisbe E, Alcón A | title = Effects of omeprazole, ranitidine, famotidine and placebo on gastric secretion in patients undergoing elective surgery | journal = British Journal of Anaesthesia | volume = 69 | issue = 4 | pages = 404–6 | date = October 1992 | pmid = 1419452 | doi = 10.1093/bja/69.4.404 | doi-access = free | title-link = doi }}</ref><ref>{{cite journal | vauthors = Vila P, Vallès J, Canet J, Melero A, Vidal F | title = Acid aspiration prophylaxis in morbidly obese patients: famotidine vs. ranitidine | journal = Anaesthesia | volume = 46 | issue = 11 | pages = 967–9 | date = November 1991 | pmid = 1750602 | doi = 10.1111/j.1365-2044.1991.tb09860.x | doi-access = free | title-link = doi }}</ref><ref>{{cite journal | vauthors = Jahr JS, Burckart G, Smith SS, Shapiro J, Cook DR | title = Effects of famotidine on gastric pH and residual volume in pediatric surgery | journal = Acta Anaesthesiologica Scandinavica | volume = 35 | issue = 5 | pages = 457–60 | date = July 1991 | pmid = 1887750 | doi = 10.1111/j.1399-6576.1991.tb03328.x | s2cid = 44356956 }}</ref>
* Given to surgery patients before operations to reduce the risk of [[aspiration pneumonia]].<ref name="pmid1419452">{{cite journal | vauthors = Escolano F, Castaño J, López R, Bisbe E, Alcón A | title = Effects of omeprazole, ranitidine, famotidine and placebo on gastric secretion in patients undergoing elective surgery | journal = British Journal of Anaesthesia | volume = 69 | issue = 4 | pages = 404–6 | date = October 1992 | pmid = 1419452 | doi = 10.1093/bja/69.4.404 | doi-access = free | title-link = doi }}</ref><ref name="pmid1750602">{{cite journal | vauthors = Vila P, Vallès J, Canet J, Melero A, Vidal F | title = Acid aspiration prophylaxis in morbidly obese patients: famotidine vs. ranitidine | journal = Anaesthesia | volume = 46 | issue = 11 | pages = 967–9 | date = November 1991 | pmid = 1750602 | doi = 10.1111/j.1365-2044.1991.tb09860.x | doi-access = free | title-link = doi }}</ref><ref name="pmid1887750">{{cite journal | vauthors = Jahr JS, Burckart G, Smith SS, Shapiro J, Cook DR | title = Effects of famotidine on gastric pH and residual volume in pediatric surgery | journal = Acta Anaesthesiologica Scandinavica | volume = 35 | issue = 5 | pages = 457–60 | date = July 1991 | pmid = 1887750 | doi = 10.1111/j.1399-6576.1991.tb03328.x | s2cid = 44356956 }}</ref>


== Pharmacokinetics ==
== Pharmacokinetics ==
Famotidine has a delayed onset of action, beginning after 90 minutes. However, famotidine has a duration of effect of at least {{convert|540|minutes|hour}}. At its peak effect, {{convert|210|minutes|hour}} after administration, famotidine reduces acid secretion by 7.3 mmol per 30 minutes.<ref>{{cite journal | vauthors = Feldman M | title = Comparison of the effects of over-the-counter famotidine and calcium carbonate antacid on postprandial gastric acid. A randomized controlled trial | journal = JAMA | volume = 275 | issue = 18 | pages = 1428–1431 | date = May 1996 | pmid = 8618369 | doi = 10.1001/jama.1996.03530420056036 }}</ref>
Famotidine has a delayed onset of action, beginning after 90 minutes. However, famotidine has a duration of effect of at least {{convert|540|minutes|hour}}. At its peak effect, {{convert|210|minutes|hour}} after administration, famotidine reduces acid secretion by 7.3 mmol per 30 minutes.<ref name="pmid8618369">{{cite journal | vauthors = Feldman M | title = Comparison of the effects of over-the-counter famotidine and calcium carbonate antacid on postprandial gastric acid. A randomized controlled trial | journal = JAMA | volume = 275 | issue = 18 | pages = 1428–1431 | date = May 1996 | pmid = 8618369 | doi = 10.1001/jama.1996.03530420056036 }}</ref>


== Side effects ==
== Side effects ==
The most common side effects associated with famotidine use include [[headache]], [[dizziness]], and [[constipation]] or [[diarrhea]].<ref>{{Cite web|url=https://www.rxlist.com/pepcid-side-effects-drug-center.htm|title=Common Side Effects of Pepcid (Famotidine) Drug Center|website=RxList|language=en|access-date=2 March 2019|archive-date=6 March 2019|archive-url=https://web.archive.org/web/20190306043201/https://www.rxlist.com/pepcid-side-effects-drug-center.htm|url-status=live}}</ref><ref>{{Cite web|url=https://www.webmd.com/drugs/2/drug-5035-2033/famotidine-oral/famotidine-oral/details|title=Drugs & Medications|website=www.webmd.com|language=en|access-date=2 March 2019|archive-date=6 March 2019|archive-url=https://web.archive.org/web/20190306042734/https://www.webmd.com/drugs/2/drug-5035-2033/famotidine-oral/famotidine-oral/details|url-status=live}}</ref>
The most common side effects associated with famotidine use include [[headache]], [[dizziness]], and [[constipation]] or [[diarrhea]].<ref name="RxList-Common-Side">{{cite web|url=https://www.rxlist.com/pepcid-side-effects-drug-center.htm|title=Common Side Effects of Pepcid (Famotidine) Drug Center|website=RxList|access-date=2 March 2019|archive-date=6 March 2019|archive-url=https://web.archive.org/web/20190306043201/https://www.rxlist.com/pepcid-side-effects-drug-center.htm|url-status=live}}</ref><ref name="webmd-Drug-Medications">{{cite web|url=https://www.webmd.com/drugs/2/drug-5035-2033/famotidine-oral/famotidine-oral/details|title=Drugs & Medications|website=www.webmd.com|access-date=2 March 2019|archive-date=6 March 2019|archive-url=https://web.archive.org/web/20190306042734/https://www.webmd.com/drugs/2/drug-5035-2033/famotidine-oral/famotidine-oral/details|url-status=live}}</ref>


Famotidine may contribute to [[QT prolongation]],<ref>{{cite journal |vauthors=Fazio G, Vernuccio F, Grutta G, Re GL |title=Drugs to be avoided in patients with long QT syndrome: Focus on the anaesthesiological management. |journal=World Journal of Cardiology |date=26 April 2013 |volume=5 |issue=4 |pages=87–93 |doi=10.4330/wjc.v5.i4.87 |pmid=23675554|pmc=3653016 |doi-access=free }}</ref> particularly when used with other QT-elongating drugs, or in people with poor [[kidney function]].<ref>{{cite journal |vauthors=Lee KW, Kayser SR, Hongo RH, Tseng ZH, Scheinman MM |title=Famotidine and long QT syndrome |journal=The American Journal of Cardiology |date=May 2004 |volume=93 |issue=10 |pages=1325–1327 |doi=10.1016/j.amjcard.2004.02.025|pmid=15135720 }}</ref>
Famotidine may contribute to [[QT prolongation]],<ref name="pmid23675554">{{cite journal |vauthors=Fazio G, Vernuccio F, Grutta G, Re GL |title=Drugs to be avoided in patients with long QT syndrome: Focus on the anaesthesiological management. |journal=World Journal of Cardiology |date=26 April 2013 |volume=5 |issue=4 |pages=87–93 |doi=10.4330/wjc.v5.i4.87 |pmid=23675554|pmc=3653016 |doi-access=free }}</ref> particularly when used with other QT-elongating drugs, or in people with poor [[kidney function]].<ref name="pmid15135720">{{cite journal |vauthors=Lee KW, Kayser SR, Hongo RH, Tseng ZH, Scheinman MM |title=Famotidine and long QT syndrome |journal=The American Journal of Cardiology |date=May 2004 |volume=93 |issue=10 |pages=1325–1327 |doi=10.1016/j.amjcard.2004.02.025|pmid=15135720 }}</ref>


== Mechanism of action==
==Mechanism of action==
Activation of H<sub>2</sub> receptors located on [[parietal cells]] stimulates [[Hydrogen potassium ATPase|proton pumps]] to secrete acid into the stomach lumen. Famotidine, an [[H2 antagonist|H<sub>2</sub> antagonist]], blocks the action of [[histamine]] on the parietal cells, ultimately reducing acid secretion into the stomach.
Activation of H<sub>2</sub> receptors located on [[parietal cells]] stimulates [[Hydrogen potassium ATPase|proton pumps]] to secrete acid into the stomach lumen. Famotidine, an [[H2 antagonist|H<sub>2</sub> antagonist]], blocks the action of [[histamine]] on the parietal cells, ultimately reducing acid secretion into the stomach.


== Interactions ==
== Interactions ==


Unlike [[cimetidine]], the first H<sub>2</sub> 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. <ref>{{cite journal | vauthors = Wang X, Boffito M, Zhang J, Chung E, Zhu L, Wu Y, Patterson K, Kashuba A, Tebas P, Child M, Mahnke L, Bertz R | display-authors = 6 | title = Effects of the H2-receptor antagonist famotidine on the pharmacokinetics of atazanavir-ritonavir with or without tenofovir in HIV-infected patients | journal = AIDS Patient Care and STDs | volume = 25 | issue = 9 | pages = 509–515 | date = September 2011 | pmid = 21770762 | pmc = 3157302 | doi = 10.1089/apc.2011.0113 }}</ref><ref>{{cite journal | vauthors = Hegazy SK, El-Haggar SM, Alhassanin SA, El-Berri EI | title = Comparative randomized trial evaluating the effect of proton pump inhibitor versus histamine 2 receptor antagonist as an adjuvant therapy in diffuse large B-cell lymphoma | journal = Medical Oncology | volume = 38 | issue = 1 | pages = 4 | date = January 2021 | pmid = 33394214 | doi = 10.1007/s12032-020-01452-z | s2cid = 230485193 }}</ref><ref>{{cite journal | vauthors = Lim SG, Sawyerr AM, Hudson M, Sercombe J, Pounder RE | title = Short report: the absorption of fluconazole and itraconazole under conditions of low intragastric acidity | journal = Alimentary Pharmacology & Therapeutics | volume = 7 | issue = 3 | pages = 317–321 | date = June 1993 | pmid = 8117350 | doi = 10.1111/j.1365-2036.1993.tb00103.x | s2cid = 20462864 }}</ref>
Unlike [[cimetidine]], the first H<sub>2</sub> 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 [[antiretroviral]]s such as [[atazanavir]], [[chemotherapeutic]]s such as [[doxorubicin]], and [[antifungal]] medications such as [[itraconazole]]. <ref name="pmid21770762">{{cite journal | vauthors = Wang X, Boffito M, Zhang J, Chung E, Zhu L, Wu Y, Patterson K, Kashuba A, Tebas P, Child M, Mahnke L, Bertz R | title = Effects of the H2-receptor antagonist famotidine on the pharmacokinetics of atazanavir-ritonavir with or without tenofovir in HIV-infected patients | journal = AIDS Patient Care and STDs | volume = 25 | issue = 9 | pages = 509–515 | date = September 2011 | pmid = 21770762 | pmc = 3157302 | doi = 10.1089/apc.2011.0113 }}</ref><ref name="pmid33394214">{{cite journal | vauthors = Hegazy SK, El-Haggar SM, Alhassanin SA, El-Berri EI | title = Comparative randomized trial evaluating the effect of proton pump inhibitor versus histamine 2 receptor antagonist as an adjuvant therapy in diffuse large B-cell lymphoma | journal = Medical Oncology | volume = 38 | issue = 1 | pages = 4 | date = January 2021 | pmid = 33394214 | doi = 10.1007/s12032-020-01452-z | s2cid = 230485193 }}</ref><ref name="pmid8117350">{{cite journal | vauthors = Lim SG, Sawyerr AM, Hudson M, Sercombe J, Pounder RE | title = Short report: the absorption of fluconazole and itraconazole under conditions of low intragastric acidity | journal = Alimentary Pharmacology & Therapeutics | volume = 7 | issue = 3 | pages = 317–321 | date = June 1993 | pmid = 8117350 | doi = 10.1111/j.1365-2036.1993.tb00103.x | s2cid = 20462864 }}</ref>


== History ==
== History ==
Famotidine was developed by [[Yamanouchi Pharmaceutical]] Co.<ref>{{US patent reference |number=4283408 |issue-date=11 August 1981 |inventor=Yasufumi Hirata, Isao Yanagisawa, Yoshio Ishii, Shinichi Tsukamoto, Noriki Ito, Yasuo Isomura and Masaaki Takeda | title = Guanidinothiazole compounds, process for preparation and gastric inhibiting compositions containing them }}</ref> It was licensed in the mid-1980s by [[Merck & Co.]]<ref>{{cite web|url=http://mediwire.skyscape.com/main/Default.aspx?P=Content&ArticleID=23882 |title=Sankyo Pharma |publisher=Skyscape Mediwire |year=2002 |access-date=31 October 2009 |url-status=dead |archive-url=https://web.archive.org/web/20090223125527/http://mediwire.skyscape.com/main/Default.aspx?P=Content&ArticleID=23882 |archive-date=23 February 2009 }}</ref> 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]].<ref>{{cite journal | vauthors = Howard JM, Chremos AN, Collen MJ, McArthur KE, Cherner JA, Maton PN, Ciarleglio CA, Cornelius MJ, Gardner JD, Jensen RT | display-authors = 6 | title = Famotidine, a new, potent, long-acting histamine H2-receptor antagonist: comparison with cimetidine and ranitidine in the treatment of Zollinger-Ellison syndrome | journal = Gastroenterology | volume = 88 | issue = 4 | pages = 1026–33 | date = April 1985 | pmid = 2857672 | doi = 10.1016/s0016-5085(85)80024-x | doi-access = free }}</ref>
Famotidine was developed by [[Yamanouchi Pharmaceutical]] Co.<ref name="US-patent-4283408">{{US patent reference |number=4283408 |issue-date=11 August 1981 |inventor=Yasufumi Hirata, Isao Yanagisawa, Yoshio Ishii, Shinichi Tsukamoto, Noriki Ito, Yasuo Isomura and Masaaki Takeda | title = Guanidinothiazole compounds, process for preparation and gastric inhibiting compositions containing them }}</ref> It was licensed in the mid-1980s by [[Merck & Co.]]<ref name="Skyscape Mediwire-2002">{{cite web|url=http://mediwire.skyscape.com/main/Default.aspx?P=Content&ArticleID=23882 |title=Sankyo Pharma |publisher=Skyscape Mediwire |year=2002 |access-date=31 October 2009 |url-status=dead |archive-url=https://web.archive.org/web/20090223125527/http://mediwire.skyscape.com/main/Default.aspx?P=Content&ArticleID=23882 |archive-date=23 February 2009 }}</ref> 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]].<ref name="pmid2857672">{{cite journal | vauthors = Howard JM, Chremos AN, Collen MJ, McArthur KE, Cherner JA, Maton PN, Ciarleglio CA, Cornelius MJ, Gardner JD, Jensen RT | title = Famotidine, a new, potent, long-acting histamine H2-receptor antagonist: comparison with cimetidine and ranitidine in the treatment of Zollinger-Ellison syndrome | journal = Gastroenterology | volume = 88 | issue = 4 | pages = 1026–33 | date = April 1985 | pmid = 2857672 | doi = 10.1016/s0016-5085(85)80024-x | doi-access = free }}</ref>


It was first marketed in 1981. Pepcid RPD [[orally disintegrating tablet]]s were released in 1999. Generic preparations became available in 2001, e.g. Fluxid ([[Schwarz Pharma|Schwarz]]) or Quamatel ([[Gedeon Richter Ltd.]]).
It was first marketed in 1981. Pepcid RPD [[orally disintegrating tablet]]s were released in 1999. Generic preparations became available in 2001, e.g. Fluxid ([[Schwarz Pharma|Schwarz]]) or Quamatel ([[Gedeon Richter Ltd.]]).


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 until its discontinuation in April 2015.<ref>{{cite web|url=http://www.medicines.org.uk/emc/medicine/20012|title=PepcidTwo Chewable Tablet|access-date=7 June 2015|archive-url=https://web.archive.org/web/20160718071357/http://www.medicines.org.uk/emc/medicine/20012|archive-date=18 July 2016|url-status=dead}}</ref>
In the United States and Canada, a product called [[Pepcid Complete]], which combines famotidine with an [[antacid]] in a chewable tablet to relieve the symptoms of excess stomach acid quickly, is available. In the UK, this product was known as PepcidTwo until its discontinuation in April 2015.<ref name="PepcidTwo-Chewable-Tablet">{{cite web|url=http://www.medicines.org.uk/emc/medicine/20012|title=PepcidTwo Chewable Tablet|access-date=7 June 2015|archive-url=https://web.archive.org/web/20160414193041/http://www.medicines.org.uk/emc/medicine/20012|archive-date=14 April 2016|url-status=dead}}</ref>


Famotidine has poor [[bioavailability|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.<ref>{{cite web |url = http://www.farmavita.net/content/view/1012/84/ |title = Formulation and Evaluation of Gastroretentive Floating Tablets of Famotidine |year = 2008 |access-date = 31 January 2009 |publisher = Farmavita.Net |archive-url = https://web.archive.org/web/20160329235131/http://www.farmavita.net/content/view/1012/84/ |archive-date = 29 March 2016 |url-status = dead }}</ref>
Famotidine has poor [[bioavailability|bioavailibility]] (50%) due to its low solubility in the high pH of the intestines. Researchers are developing formulations that use gastroretentive drug delivery systems such as floating tablets to increase bioavailability by promoting local delivery (directly into the stomach wall) of these drugs to receptors in the parietal cell membrane.<ref name="Farmavita.Net-2008">{{cite web |url = http://www.farmavita.net/content/view/1012/84/ |title = Formulation and Evaluation of Gastroretentive Floating Tablets of Famotidine |year = 2008 |access-date = 31 January 2009 |publisher = Farmavita.Net |archive-url = https://web.archive.org/web/20160329235131/http://www.farmavita.net/content/view/1012/84/ |archive-date = 29 March 2016 |url-status = dead }}</ref>


== Society and culture ==
== Society and culture ==
Certain preparations of famotidine are available [[Over-the-counter drug|over the counter]] (OTC) in various countries. In the United States and Canada, 10&nbsp;mg and 20&nbsp;mg tablets, sometimes in combination with an [[antacid]],<ref>[[Pepcid Complete]]</ref><ref>{{cite web|url=https://www.nlm.nih.gov/medlineplus/druginfo/meds/a687011.html|title=Famotidine|work=Medline Plus|access-date=21 March 2018|archive-date=5 July 2016|archive-url=https://web.archive.org/web/20160705112509/https://www.nlm.nih.gov/medlineplus/druginfo/meds/a687011.html|url-status=live}}</ref> are available OTC. Larger doses still require a prescription.
Certain preparations of famotidine are available [[Over-the-counter drug|over-the-counter]] (OTC) in various countries. In the United States and Canada, 10&nbsp;mg and 20&nbsp;mg tablets, sometimes in combination with an [[antacid]],<ref name="Pepcid-Complete">[[Pepcid Complete]]</ref><ref name="Medline-Plus-Famotidine">{{cite web|url=https://www.nlm.nih.gov/medlineplus/druginfo/meds/a687011.html|title=Famotidine|work=Medline Plus|access-date=21 March 2018|archive-date=4 October 2022|archive-url=https://web.archive.org/web/20221004043822/https://medlineplus.gov/druginfo/meds/a687011.html|url-status=live}}</ref> are available OTC. Larger doses still require a prescription.


Formulations of famotidine in combination with [[ibuprofen]] were marketed by [[Horizon Pharma]] under the trade name Duexis.<ref>{{cite web |title=Duexis |url=https://www.drugs.com/duexis.html |website=Drugs.com |access-date=28 April 2020 |archive-date=18 July 2017 |archive-url=https://web.archive.org/web/20170718023727/https://www.drugs.com/duexis.html |url-status=live }}</ref>
Formulations of famotidine in combination with [[ibuprofen]] were marketed by [[Horizon Pharma]] under the trade name Duexis.<ref name="Drugs.com-Duexis">{{cite web |title=Duexis |url=https://www.drugs.com/duexis.html |website=Drugs.com |access-date=28 April 2020 |archive-date=26 November 2020 |archive-url=https://web.archive.org/web/20201126182256/https://www.drugs.com/duexis.html |url-status=live }}</ref>
{{clear}}
{{clear}}


== Research ==
== Research ==
===COVID-19===
===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 treatment of COVID-19.<ref> {{cite magazine |url= https://www.science.org/content/article/new-york-clinical-trial-quietly-tests-heartburn-remedy-against-coronavirus |title= New York clinical trial quietly tests heartburn remedy against coronavirus | vauthors = Borrell B |date= 26 April 2020 |magazine = Science Magazine }} </ref><ref> {{cite journal | vauthors = Malone RW, Tisdall P, Fremont-Smith P, Liu Y, Huang XP, White KM, Miorin L, Moreno E, Alon A, Delaforge E, Hennecker CD, Wang G, Pottel J, Blair RV, Roy CJ, Smith N, Hall JM, Tomera KM, Shapiro G, Mittermaier A, Kruse AC, García-Sastre A, Roth BL, Glasspool-Malone J, Ricke DO | display-authors = 6 | title = COVID-19: Famotidine, Histamine, Mast Cells, and Mechanisms | journal = Frontiers in Pharmacology | year = 2021 | volume = 12 | pages = 633680 | pmid = 33833683 | pmc = 8021898 | doi = 10.3389/fphar.2021.633680| doi-access = free }} </ref> Famotidine was researched for potential benefit in treating [[COVID-19]] following hypotheses at the start of the pandemic that it may be an applicable medication. No good evidence of benefit was found.<ref>{{cite journal | vauthors = Long B, Chavez S, Carius BM, Brady WJ, Liang SY, Koyfman A, Gottlieb M | title = Clinical update on COVID-19 for the emergency and critical care clinician: Medical management | journal = The American Journal of Emergency Medicine | volume = 56 | issue = | pages = 158–170 | date = June 2022 | pmid = 35397357 | pmc = 8956349 | doi = 10.1016/j.ajem.2022.03.036 | type = Review }}</ref>
At the start of the [[COVID-19 pandemic]], some doctors observed that anecdotally some hospitalized patients in China may have had better outcomes on famotidine than other patients who were not taking famotidine. This led to hypotheses about use of famotidine in treatment of [[COVID-19]].<ref name="Borrell-2020">{{cite journal |url= https://www.science.org/content/article/new-york-clinical-trial-quietly-tests-heartburn-remedy-against-coronavirus |title= New York clinical trial quietly tests heartburn remedy against coronavirus |vauthors= Borrell B |date= April 2020 |journal= Science |doi= 10.1126/science.abc4739 |doi-access= free |title-link= doi |access-date= 20 September 2022 |archive-date= 29 April 2020 |archive-url= https://web.archive.org/web/20200429193819/https://www.sciencemag.org/news/2020/04/new-york-clinical-trial-quietly-tests-heartburn-remedy-against-coronavirus |url-status= live }}</ref><ref name="pmid33833683"> {{cite journal |vauthors=Malone RW, Tisdall P, Fremont-Smith P, Liu Y, Huang XP, White KM, Miorin L, Moreno E, Alon A, Delaforge E, Hennecker CD, Wang G, Pottel J, Blair RV, Roy CJ, Smith N, Hall JM, Tomera KM, Shapiro G, Mittermaier A, Kruse AC, García-Sastre A, Roth BL, Glasspool-Malone J, Ricke DO |title=COVID-19: Famotidine, Histamine, Mast Cells, and Mechanisms |journal=Frontiers in Pharmacology |year=2021 |volume=12 |pages=633680 |pmid=33833683 |pmc=8021898 |doi=10.3389/fphar.2021.633680 |doi-access=free}}</ref> Famotidine was considered a possible treatment for COVID-19 due to its potential [[anti-inflammatory]] effects. It was thought that famotidine could modify lung inflammation caused by [[Coronavirus|coronaviruses]]. However, studies have shown that famotidine is not effective in reducing mortality or improving recovery in COVID-19 patients.<ref name="pmid36462586">{{cite journal |vauthors=Cheema HA, Shafiee A, Athar M, Shahid A, Awan RU, Afifi AM, Shah J, Jalal PK |title=No evidence of clinical efficacy of famotidine for the treatment of COVID-19: a systematic review and meta-analysis |journal=J Infect |volume=86 |issue=2 |pages=154–225 |date=February 2023 |pmid=36462586 |pmc=9711899 |doi=10.1016/j.jinf.2022.11.022 |url=}}</ref> Famotidine primarily works by blocking the effects of histamine and has some potential mechanisms of action that may contribute to its anti-inflammatory properties, including the inhibition of the production of certain pro-inflammatory cytokines such as [[TNF-alpha]] and [[Interleukin 6|IL-6]].<ref name="pmid37399740"/><ref name="pmid35578169"/> Another hypothesis was that famotidine might activate the [[vagus nerve]] inflammatory reflex to attenuate cytokine storm.<ref name="pmid35578169">{{cite journal |vauthors=Yang H, George SJ, Thompson DA, Silverman HA, Tsaava T, Tynan A, Pavlov VA, Chang EH, Andersson U, Brines M, Chavan SS, Tracey KJ |title=Famotidine activates the vagus nerve inflammatory reflex to attenuate cytokine storm |journal=Mol Med |volume=28 |issue=1 |pages=57 |date=May 2022 |pmid=35578169 |pmc=9109205 |doi=10.1186/s10020-022-00483-8 |url= |doi-access=free }}</ref> Yet another hypothesis was that famotidine can reduce the activation of [[mast cell]]s and the subsequent release of [[inflammatory mediators]], therefore acting as a [[mast cell stabilizer]].<ref name="pmid37529714">{{cite journal |vauthors=Salvucci F, Codella R, Coppola A, Zacchei I, Grassi G, Anti ML, Nitisoara N, Luzi L, Gazzaruso C |title=Antihistamines improve cardiovascular manifestations and other symptoms of long-COVID attributed to mast cell activation |journal=Front Cardiovasc Med |volume=10 |issue= |pages=1202696 |date=2023 |pmid=37529714 |pmc=10388239 |doi=10.3389/fcvm.2023.1202696 |url= |doi-access=free }}</ref><ref name="pmid37399740">{{cite journal |vauthors=Kow CS, Ramachandram DS, Hasan SS |title=Famotidine: A potential mitigator of mast cell activation in post-COVID-19 cognitive impairment |journal=J Psychosom Res |volume=172 |issue= |pages=111425 |date=September 2023 |pmid=37399740 |pmc=10292911 |doi=10.1016/j.jpsychores.2023.111425 |url=}}</ref> However, while famotidine may have some anti-inflammatory effects, there is currently insufficient evidence to support its use for treating inflammation associated with COVID-19.<ref name="pmid36462586" /> Therefore, it is not recommended for this purpose.<ref name="pmid35397357">{{cite journal | vauthors = Long B, Chavez S, Carius BM, Brady WJ, Liang SY, Koyfman A, Gottlieb M | title = Clinical update on COVID-19 for the emergency and critical care clinician: Medical management | journal = The American Journal of Emergency Medicine | volume = 56 | issue = | pages = 158–170 | date = June 2022 | pmid = 35397357 | pmc = 8956349 | doi = 10.1016/j.ajem.2022.03.036 | type = Review }}</ref>

===Other===
Small-scale studies have shown inconsistent and inconclusive evidence of efficacy in treatment-resistant [[schizophrenia]].<ref name="Famotidine-Augmentation-in-Schizophrenia:-Hope-or-Hype?">{{cite journal | title = Famotidine Augmentation in Schizophrenia: Hope or Hype? | url = https://www.psychiatrist.com/jcp/famotidine-augmentation-schizophrenia-hope-hype/ | journal = The Journal of Clinical Psychiatry | date = 2013 | doi = 10.4088/JCP.13f08707 | access-date = 11 January 2024 | last1 = Andrade | first1 = Chittaranjan | volume = 74 | issue = 9 | pages = e855–e858 | pmid = 24107771 | archive-date = 11 January 2024 | archive-url = https://web.archive.org/web/20240111121249/https://www.psychiatrist.com/jcp/famotidine-augmentation-schizophrenia-hope-hype/ | url-status = live }}</ref>


== Veterinary uses ==
== Veterinary uses ==
Famotidine is given to dogs and cats with acid reflux.<ref>{{cite web|url=http://www.petmd.com/pet-medication/famotidine|title=Famotidine|website=PetMD|access-date=7 June 2015|archive-date=19 May 2015|archive-url=https://web.archive.org/web/20150519053023/http://www.petmd.com/pet-medication/famotidine|url-status=live}}</ref>
Famotidine is given to dogs and cats with acid reflux.<ref name="PetMD-Famotidine">{{cite web|url=http://www.petmd.com/pet-medication/famotidine|title=Famotidine|website=PetMD|access-date=7 June 2015|archive-date=19 May 2015|archive-url=https://web.archive.org/web/20150519053023/http://www.petmd.com/pet-medication/famotidine|url-status=live}}</ref>


== References ==
== References ==

Latest revision as of 19:18, 7 December 2024

Famotidine
Clinical data
Pronunciation/fəˈmɒtɪdn/
Trade namesPepcid, Zantac 360, others
AHFS/Drugs.comMonograph
MedlinePlusa687011
License data
Pregnancy
category
Routes of
administration
By mouth, intravenous
Drug classHistamine H2 receptor antagonist
ATC code
Legal status
Legal status
Pharmacokinetic data
Bioavailability40–45% (by mouth)[2]
Protein binding15–20%[2]
Onset of action90 minutes
Elimination half-life2.5–3.5 hours[2]
Duration of action9 hours
ExcretionKidney (25–30% unchanged [Oral])[2]
Identifiers
  • 3-[({2-[(diaminomethylidene)amino]-1,3-thiazol-4-yl}methyl)sulfanyl]-N-sulfamoylpropanimidamide
CAS Number
PubChem CID
IUPHAR/BPS
DrugBank
ChemSpider
UNII
KEGG
ChEBI
ChEMBL
PDB ligand
CompTox Dashboard (EPA)
ECHA InfoCard100.116.793 Edit this at Wikidata
Chemical and physical data
FormulaC8H15N7O2S3
Molar mass337.44 g·mol−1
3D model (JSmol)
  • NS(=O)(=O)/N=C(\N)CCSCc1csc(n1)N=C(N)N
  • 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) checkY
  • Key:XUFQPHANEAPEMJ-UHFFFAOYSA-N checkY
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Famotidine, sold under the brand name Pepcid among others, is a histamine H2 receptor antagonist medication that decreases stomach acid production.[4] It is used to treat peptic ulcer disease, gastroesophageal reflux disease, and Zollinger-Ellison syndrome.[4] It is taken by mouth or by injection into a vein.[4] It begins working within an hour.[4]

Common side effects include headache, abdominal pain, diarrhea or constipation, and dizziness.[4] Serious side effects may include pneumonia and seizures.[4][5] Use in pregnancy appears safe but has not been well studied, while use during breastfeeding is not recommended.[1]

Famotidine was patented in 1979 and came into medical use in 1985.[6] It is available as a generic medication.[5] In 2022, it was the 49th most commonly prescribed medication in the United States, with more than 13 million prescriptions.[7][8]

Medical uses

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Pharmacokinetics

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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

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

Famotidine may contribute to QT prolongation,[23] particularly when used with other QT-elongating drugs, or in people with poor kidney function.[24]

Mechanism of action

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Activation of H2 receptors located on parietal cells stimulates proton pumps to secrete acid into the stomach lumen. Famotidine, an H2 antagonist, blocks the action of histamine on the parietal cells, ultimately reducing acid secretion into the stomach.

Interactions

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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

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Famotidine was developed by Yamanouchi Pharmaceutical Co.[28] It was licensed in the mid-1980s by Merck & Co.[29] 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.[30]

It was first marketed in 1981. Pepcid RPD orally disintegrating tablets were released in 1999. Generic preparations became available in 2001, e.g. Fluxid (Schwarz) or Quamatel (Gedeon Richter Ltd.).

In the United States and Canada, a product called Pepcid Complete, which combines famotidine with an antacid in a chewable tablet to relieve the symptoms of excess stomach acid quickly, is available. In the UK, this product was known as PepcidTwo until its discontinuation in April 2015.[31]

Famotidine has poor bioavailibility (50%) due to its low solubility in the high pH of the intestines. Researchers are developing formulations that use gastroretentive drug delivery systems such as floating tablets to increase bioavailability by promoting local delivery (directly into the stomach wall) of these drugs to receptors in the parietal cell membrane.[32]

Society and culture

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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 ibuprofen were marketed by Horizon Pharma under the trade name Duexis.[35]

Research

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COVID-19

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At the start of the COVID-19 pandemic, some doctors observed that anecdotally some hospitalized patients in China may have had better outcomes on famotidine than other patients who were not taking famotidine. This led to hypotheses about use of famotidine in treatment of COVID-19.[36][37] Famotidine was considered a possible treatment for COVID-19 due to its potential anti-inflammatory effects. It was thought that famotidine could modify lung inflammation caused by coronaviruses. However, studies have shown that famotidine is not effective in reducing mortality or improving recovery in COVID-19 patients.[38] Famotidine primarily works by blocking the effects of histamine and has some potential mechanisms of action that may contribute to its anti-inflammatory properties, including the inhibition of the production of certain pro-inflammatory cytokines such as TNF-alpha and IL-6.[39][40] Another hypothesis was that famotidine might activate the vagus nerve inflammatory reflex to attenuate cytokine storm.[40] Yet another hypothesis was that famotidine can reduce the activation of mast cells and the subsequent release of inflammatory mediators, therefore acting as a mast cell stabilizer.[41][39] However, while famotidine may have some anti-inflammatory effects, there is currently insufficient evidence to support its use for treating inflammation associated with COVID-19.[38] Therefore, it is not recommended for this purpose.[42]

Other

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

Veterinary uses

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

References

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