cefalexin
{{Short description|Beta-lactam antibiotic}}
{{Use dmy dates|date=October 2021}}
{{cs1 config |name-list-style=vanc |display-authors=6}}
{{Drugbox
| Watchedfields = changed
| verifiedrevid = 457630940
| image = Cefalexin.svg
| image_class = skin-invert-image
| alt =
| image2 = Cefalexin-from-xtal-3D-bs-17.png
| image_class2 = bg-transparent
| alt2 =
| BAN = cephalexin
| USAN = cephalexin
| pronounce = {{IPAc-en|ˌ|s|ɛ|f|ə|ˈ|l|ɛ|k|s|ᵻ|n}}
| tradename = Keflex, others
| Drugs.com = {{Drugs.com|monograph|cephalexin}}
| MedlinePlus = a682733
| DailyMedID = Cephalexin
| pregnancy_AU = A
| pregnancy_category =
| routes_of_administration = By mouth
| class = First-generation cephalosporin
| ATC_prefix = J01
| ATC_suffix = DB01
| ATC_supplemental = {{ATCvet|J51|DB01}}
| legal_AU = S4
| legal_CA = Rx-only
| legal_CA_comment =
| legal_UK = POM
| legal_US = Rx-only
| legal_EU = Rx-only
| bioavailability = Well absorbed
| protein_bound = 15%
| metabolism = 80% excreted unchanged in urine within 6 hours of administration
| elimination_half-life = 0.6–1.2 hoursMcEvoy, G.K. (ed.). American Hospital Formulary Service — Drug Information 95. Bethesda, MD: American Society of Hospital Pharmacists, Inc., 1995 (Plus Supplements 1995)., p. 166
| excretion = Kidney
| CAS_number_Ref = {{cascite|correct|??}}
| CAS_number = 15686-71-2
| PubChem = 2666
| IUPHAR_ligand = 4832
| DrugBank_Ref = {{drugbankcite|correct|drugbank}}
| DrugBank = DB00567
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 25541
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 5SFF1W6677
| KEGG_Ref = {{keggcite|correct|kegg}}
| KEGG = D00263
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 3534
| ChEMBL_Ref = {{ebicite|correct|EBI}}
| ChEMBL = 1727
| synonyms = cephalexin
| IUPAC_name = (7R)-3-methyl-7-(α-D-phenylglycylamino)-3-cephem-4-carboxylic acid monohydrate
| C=16 | H=17 | N=3 | O=4 | S=1
| smiles = O=C2N1/C(=C(\CS[C@@H]1[C@@H]2NC(=O)[C@@H](c3ccccc3)N)C)C(=O)O
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/C16H17N3O4S/c1-8-7-24-15-11(14(21)19(15)12(8)16(22)23)18-13(20)10(17)9-5-3-2-4-6-9/h2-6,10-11,15H,7,17H2,1H3,(H,18,20)(H,22,23)/t10-,11-,15-/m1/s1
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = ZAIPMKNFIOOWCQ-UEKVPHQBSA-N
| melting_point = 326.8
}}
Cefalexin, also spelled cephalexin, is an antibiotic that can treat a number of bacterial infections. It kills gram-positive and some gram-negative bacteria by disrupting the growth of the bacterial cell wall. Cefalexin is a β-lactam antibiotic within the class of first-generation cephalosporins. It works similarly to other agents within this class, including intravenous cefazolin, but can be taken by mouth.{{cite book| vauthors = Brunton LL |title=Goodman & Gilman's pharmacological basis of therapeutics.|date=2011|publisher=McGraw-Hill|location=New York|isbn=978-0071624428 |edition=12th |chapter= Chapter 53: Penicillins, Cephalosporins, and Other β-Lactam Antibiotics}}
Cefalexin can treat certain bacterial infections, including those of the middle ear, bone and joint, skin, and urinary tract. It may also be used for certain types of pneumonia and strep throat and to prevent bacterial endocarditis. Cefalexin is not effective against infections caused by methicillin-resistant Staphylococcus aureus (MRSA), most Enterococcus, or Pseudomonas. Like other antibiotics, cefalexin cannot treat viral infections, such as the flu, common cold or acute bronchitis. Cefalexin can be used in those who have mild or moderate allergies to penicillin. However, it is not recommended in those with severe penicillin allergies.
Common side effects include stomach upset and diarrhea. Allergic reactions or infections with Clostridioides difficile, a cause of diarrhea, are also possible. Use during pregnancy or breastfeeding does not appear to be harmful to the fetus.{{cite web|title=Prescribing medicines in pregnancy database|url=http://www.tga.gov.au/hp/medicines-pregnancy.htm|work=Australian Government|access-date=22 April 2014|date=3 March 2014|url-status=live|archive-url=https://web.archive.org/web/20140408040902/http://www.tga.gov.au/hp/medicines-pregnancy.htm#.U1Yw8Bc3tqw|archive-date=8 April 2014}}{{cite book|title=Breastfeeding and Medication|date=2013|publisher=Routledge|isbn=9781136178153|page=227|url=https://books.google.com/books?id=0Y8lbCnF1mgC&pg=PA227| vauthors = Jones W |url-status=live|archive-url=https://web.archive.org/web/20170908135050/https://books.google.com/books?id=0Y8lbCnF1mgC&pg=PA227|archive-date=8 September 2017}} It can be used in children and those over 65 years of age. Those with kidney problems may require a decrease in dose.{{cite web|title=Cephalexin|url=https://www.drugs.com/monograph/cephalexin.html|publisher=The American Society of Health-System Pharmacists|access-date=21 April 2014|url-status=live|archive-url=https://web.archive.org/web/20140501202910/http://www.drugs.com/monograph/cephalexin.html|archive-date=1 May 2014}}
Cefalexin was developed in 1967.{{cite book | veditors = Hey E |title=Neonatal formulary 5 drug use in pregnancy and the first year of life |date=2007 |publisher=Blackwell |isbn=9780470750353 |page=67 |url=https://books.google.com/books?id=aumIBqHmChwC&pg=PA67 |edition=5th |url-status=live |archive-url=https://web.archive.org/web/20170908135050/https://books.google.com/books?id=aumIBqHmChwC&pg=PA67 |archive-date=8 September 2017 }}>{{cite patent |country=US |number=3275626 |status=patent |title=Penicillin conversion via sulfoxide |pubdate=1966-09-27 |gdate=1966-09-27 |fdate=1962-07-31 |pridate=1962-07-31 |inventor=Morin RB, Jackson BG |assign1=Eli Lilly and Co |url=https://worldwide.espacenet.com/publicationDetails/biblio?CC=US&NR=3275626&KC=&FT=E&locale=en_EP }} {{Webarchive|url=https://web.archive.org/web/20220925035539/https://worldwide.espacenet.com/publicationDetails/biblio?CC=US&NR=3275626&KC=&FT=E&locale=en_EP |date=25 September 2022 }} {{Cite web |url=https://worldwide.espacenet.com/publicationDetails/biblio?CC=US&NR=3275626&KC=&FT=E&locale=en_EP |title=Espacenet - Bibliographic data |access-date=3 March 2020 |archive-date=25 September 2022 |archive-url=https://web.archive.org/web/20220925035539/https://worldwide.espacenet.com/publicationDetails/biblio?CC=US&NR=3275626&KC=&FT=E&locale=en_EP }}{{cite patent |country=US |number=3507861 |status=patent |title=Certain 3-methyl-cephalosporin compounds |pubdate=1970-04-21 |gdate=1970-04-21 |fdate=1966-09-14 |pridate=1966-09-14 |inventor=Morin RB, Jackson BG |assign1=Eli Lilly and Co |url=https://worldwide.espacenet.com/publicationDetails/biblio?CC=US&NR=3507861&KC=&FT=E&locale=en_EP }} {{Webarchive|url=https://web.archive.org/web/20220925035539/https://worldwide.espacenet.com/publicationDetails/biblio?CC=US&NR=3507861&KC=&FT=E&locale=en_EP |date=25 September 2022 }} {{Cite web |url=https://worldwide.espacenet.com/publicationDetails/biblio?CC=US&NR=3507861&KC=&FT=E&locale=en_EP |title=Espacenet - Bibliographic data |access-date=3 March 2020 |archive-date=25 September 2022 |archive-url=https://web.archive.org/web/20220925035539/https://worldwide.espacenet.com/publicationDetails/biblio?CC=US&NR=3507861&KC=&FT=E&locale=en_EP }} It was first marketed in 1969 under the brand name Keflex.{{cite book| vauthors = McPherson EM | chapter = Cefalexin |title=Pharmaceutical Manufacturing Encyclopedia.|date=2007|publisher=Elsevier|location=Burlington|isbn=9780815518563|page=915| chapter-url=https://books.google.com/books?id=_J2ti4EkYpkC&pg=PA915|edition=3rd|url-status=live|archive-url=https://web.archive.org/web/20170908135051/https://books.google.com/books?id=_J2ti4EkYpkC&pg=PA915|archive-date=8 September 2017}}{{cite book|last=Ravina|first=Enrique|title=The evolution of drug discovery : from traditional medicines to modern drugs|date=2011|publisher=Wiley-VCH|location=Weinheim|isbn=9783527326693|page=267|url=https://books.google.com/books?id=iDNy0XxGqT8C&pg=PA267|edition=1. Aufl.|url-status=live|archive-url=https://web.archive.org/web/20170908135051/https://books.google.com/books?id=iDNy0XxGqT8C&pg=PA267|archive-date=8 September 2017}} It is available as a generic medication.{{cite book | vauthors = Hanlon G, Hodges N |title =Essential Microbiology for Pharmacy and Pharmaceutical Science |date=2012 |publisher=Wiley |location=Hoboken |isbn=9781118432433 |page=140 |url=https://books.google.com/books?id=P4Ucifn76PUC&pg=PT140 |url-status=live|archive-url=https://web.archive.org/web/20170908135051/https://books.google.com/books?id=P4Ucifn76PUC&pg=PT140|archive-date=8 September 2017}} It is on the World Health Organization's List of Essential Medicines.{{cite book | vauthors = ((World Health Organization)) | title = The selection and use of essential medicines 2023: web annex A: World Health Organization model list of essential medicines: 23rd list (2023) | year = 2023 | hdl = 10665/371090 | author-link = World Health Organization | publisher = World Health Organization | location = Geneva | id = WHO/MHP/HPS/EML/2023.02 | hdl-access=free }} In 2022, it was the 101st most commonly prescribed medication in the United States, with more than 6{{nbsp}}million prescriptions.{{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 }}{{cite web | title = Cephalexin Drug Usage Statistics, United States, 2013 - 2022 | website = ClinCalc | url = https://clincalc.com/DrugStats/Drugs/Cephalexin | access-date = 30 August 2024 }} In Canada, it was the fifth most common antibiotic used in 2013.{{Cite web|url = http://publications.gc.ca/collections/collection_2014/aspc-phac/HP37-20-2013-eng.pdf|title = Human Antimicrobial Drug Use Report 2012/2013|date = November 2014|access-date = 24 February 2015|publisher = Public Health Agency of Canada (PHAC)|url-status = live|archive-url = https://web.archive.org/web/20150321041930/http://publications.gc.ca/collections/collection_2014/aspc-phac/HP37-20-2013-eng.pdf|archive-date = 21 March 2015}} In Australia, it was one of the top 10 most prescribed medications between 2017 and 2023.{{cite web | title=Medicines in the health system | website=Australian Institute of Health and Welfare | date=2 July 2024 | url=https://www.aihw.gov.au/reports/medicines/medicines-in-the-health-system | access-date=30 September 2024}}
Medical uses
File:A course of green cefalexin pills.jpg
Cefalexin can treat a number of bacterial infections including otitis media, streptococcal pharyngitis, bone and joint infections, pneumonia, cellulitis, and urinary tract infections. It may be used to prevent bacterial endocarditis. It can also be used for the prevention of recurrent urinary-tract infections.
Cefalexin does not treat methicillin-resistant Staphylococcus aureus infections.
Cefalexin is a useful alternative to penicillins in patients with penicillin intolerance. For example, penicillin is the treatment of choice for respiratory tract infections caused by Streptococcus, but cefalexin may be used as an alternative in penicillin-intolerant patients. Caution must be exercised when administering cephalosporin antibiotics to penicillin-sensitive patients, because cross-sensitivity with β-lactam antibiotics has been documented in up to 10% of patients with a documented penicillin allergy.{{cite web|title=FDA Cephalexin drug label|url=http://www.accessdata.fda.gov/drugsatfda_docs/label/2012/063024s022lbl.pdf|access-date=18 April 2014|url-status=live|archive-url=https://web.archive.org/web/20140418220539/http://www.accessdata.fda.gov/drugsatfda_docs/label/2012/063024s022lbl.pdf|archive-date=18 April 2014}}
=Pregnancy and breastfeeding=
It is categorized in category A in Australia meaning that no evidence of harm has been found after being taken by many pregnant women. Use during breastfeeding is generally safe.
Adverse effects
The most common adverse effects of cefalexin, like other oral cephalosporins, are gastrointestinal (stomach area) disturbances and hypersensitivity reactions. Gastrointestinal disturbances include nausea, vomiting, and diarrhea, the latter being the most common.{{cite web|title=Cephalexin Side Effects|url=https://www.drugs.com/sfx/cephalexin-side-effects.html|website=Drugs.com|access-date=9 February 2015|url-status=live|archive-url=https://web.archive.org/web/20150208030513/http://www.drugs.com/sfx/cephalexin-side-effects.html|archive-date=8 February 2015}} Hypersensitivity reactions include skin rashes, urticaria, fever, and anaphylaxis. Pseudomembranous colitis and Clostridioides difficile have been reported with use of cefalexin. Less common and more serious side effects include bruising of the skin and yellowing of the skin or eye whites.{{cite web |title=Cefalexin |url=https://www.nhs.uk/medicines/cefalexin/ |website=NHS |date=31 March 2020 |publisher=Crown |access-date=14 November 2022}}
Signs and symptoms of an allergic reaction include rash, itching, swelling, trouble breathing, or red, blistered, swollen, or peeling skin. Overall, cefalexin allergy occurs in less than 0.1% of patients{{Citation needed|date=August 2023|reason=The claim that adverse side effects only in 0.1% of patients is simply not credible}}. Evidence suggests that it is seen in 1% to 10% of patients with a penicillin allergy.{{cite book|title=Austria-Codex|editor=Haberfeld, H|publisher=Österreichischer Apothekerverlag|location=Vienna|year=2009|edition=2009/2010|isbn=978-3-85200-196-8|language=de}}
Interactions
Like other β-lactam antibiotics, renal excretion of cefalexin is delayed by probenecid. It is also not recommended to take cefalexin with dofetilide, live Cholera vaccine, warfarin, and cholestyramine.{{cite web |title=Cephalexin (Oral Route) |url=https://www.mayoclinic.org/drugs-supplements/cephalexin-oral-route/side-effects/drg-20073325?p=1 |website=Mayo Clinic |publisher=Mayo Foundation for Medical Education and Research |access-date=14 November 2022}} Alcohol consumption reduces the rate at which it is absorbed.{{cite journal | vauthors = Barrio Lera JP, Alvarez AI, Prieto JG | title = Effects of ethanol on the pharmacokinetics of cephalexin and cefadroxil in the rat | journal = Journal of Pharmaceutical Sciences | volume = 80 | issue = 6 | pages = 511–516 | date = June 1991 | pmid = 1941538 | doi = 10.1002/jps.2600800602 }} Cefalexin also interacts with metformin, an antidiabetic drug, and this can lead to higher concentrations of metformin in the body.{{cite journal | vauthors = Jayasagar G, Krishna Kumar M, Chandrasekhar K, Madhusudan Rao C, Madhusudan Rao Y | title = Effect of cephalexin on the pharmacokinetics of metformin in healthy human volunteers | journal = Drug Metabolism and Drug Interactions | volume = 19 | issue = 1 | pages = 41–48 | year = 2002 | pmid = 12222753 | doi = 10.1515/dmdi.2002.19.1.41 | s2cid = 26919498 }} Histamine H2 receptor antagonists like cimetidine and ranitidine may reduce the efficacy of cefalexin by delaying its absorption and altering its antimicrobial pharmacodynamics. Zinc and zinc supplements also interact with cefalexin and may reduce the amount of cefalexin in the body.
Pharmacology
=Mechanism of action=
Cefalexin is a β-lactam antibiotic of the cephalosporin family.{{cite book | vauthors = Bothara SS, Kadam KR, Mahadik KG | title = Principles of Medicinal Chemistry | volume = 1 | year = 2006 | publisher = Nirali Prakashan | location = Pune | isbn = 8185790043 | page = 81 | edition = 14th | chapter = Antibiotics | chapter-url = https://books.google.com/books?id=b2KJZksQrzoC&q=antibiotics+cephalosporin+family+Cephalexin&pg=PA81 | access-date = 7 October 2020 | archive-date = 25 September 2022 | archive-url = https://web.archive.org/web/20220925035538/https://books.google.com/books?id=b2KJZksQrzoC&q=antibiotics+cephalosporin+family+Cephalexin&pg=PA81 | url-status = live }} It is bactericidal and acts by inhibiting synthesis of the peptidoglycan layer of the bacterial cell wall.{{cite journal | vauthors = Fisher JF, Meroueh SO, Mobashery S | title = Bacterial resistance to beta-lactam antibiotics: compelling opportunism, compelling opportunity | journal = Chemical Reviews | volume = 105 | issue = 2 | pages = 395–424 | date = February 2005 | pmid = 15700950 | doi = 10.1021/cr030102i }} As cefalexin closely resembles d-alanyl-d-alanine, an amino acid ending on the peptidoglycan layer of the cell wall, it can irreversibly bind to the active site of PBP, which is essential for the synthesis of the cell wall. It is most active against gram-positive cocci, and has moderate activity against some gram-negative bacilli. However, some bacterial cells have the enzyme β-lactamase, which hydrolyzes the β-lactam ring, rendering the drug inactive. This contributes to antibacterial resistance towards cefalexin.{{cite journal | vauthors = Drawz SM, Bonomo RA | title = Three decades of beta-lactamase inhibitors | journal = Clinical Microbiology Reviews | volume = 23 | issue = 1 | pages = 160–201 | date = January 2010 | pmid = 20065329 | pmc = 2806661 | doi = 10.1128/CMR.00037-09 }}
=Pharmacokinetics=
Cefalexin is rapidly and almost completely absorbed from the gastrointestinal tract with oral administration. Absorption is slightly reduced when it is taken with food and the medication can be taken without regard for meals. Peak levels of cefalexin occur about 1 hour after administration. Maximal levels of cefalexin increase approximately linearly over a dose range of 250 to 1,000 mg.
Like most other cephalosporins, cefalexin is not metabolized or otherwise inactivated in the body.{{cite book| vauthors = Rafiei N | chapter = Cephalexin| veditors = Grayson M |title=Kucers' The Use of Antibiotics: A Clinical Review of Antibacterial, Antifungal, Antiparasitic, and Antiviral Drugs | edition = Seventh | chapter-url=https://books.google.com/books?id=3xE4DwAAQBAJ&pg=PA364|date=2 October 2017|publisher=CRC Press|isbn=978-1-4987-4796-7|pages=364–|access-date=13 July 2018|archive-date=28 August 2021|archive-url=https://web.archive.org/web/20210828023755/https://books.google.com/books?id=3xE4DwAAQBAJ&pg=PA364|url-status=live}}{{cite book | vauthors = Skidmore-Roth L |title=Mosby's Drug Guide for Nursing Students, with 2016 Update|url=https://books.google.com/books?id=g_BwCgAAQBAJ&pg=PA181|date=16 July 2015|publisher=Elsevier Health Sciences|isbn=978-0-323-17297-4|pages=181–|access-date=13 July 2018|archive-date=28 August 2021|archive-url=https://web.archive.org/web/20210828023811/https://books.google.com/books?id=g_BwCgAAQBAJ&pg=PA181|url-status=live}}
The elimination half-life of cefalexin is approximately 30 to 60 minutes in people with normal renal function. Therapeutic levels of cefalexin with oral administration are maintained for 6 to 8 hours.{{Cite web|url=https://www.medicines.org.uk/emc/product/9143/smpc|title=Cefalexin 500mg Tablets - Summary of Product Characteristics (SMPC) - (Emc)|access-date=5 March 2021|archive-date=19 April 2021|archive-url=https://web.archive.org/web/20210419094953/https://www.medicines.org.uk/emc/product/9143/smpc|url-status=live}} More than 90% of cefalexin is excreted unchanged in the urine within 8 hours.
Society and culture
It is on the World Health Organization's List of Essential Medicines. The World Health Organization classifies cefalexin as highly important for human medicine.{{cite book | vauthors=((World Health Organization)) | year=2019 | title=Critically important antimicrobials for human medicine | edition=6th revision | author-link = World Health Organization | publisher = World Health Organization | location = Geneva | hdl=10665/312266 | id=License: CC BY-NC-SA 3.0 IGO | isbn=9789241515528 | hdl-access=free }}
=Brand names=
Cefalexin is the International Nonproprietary Name (INN) and the Australian Approved Name (AAN), while cephalexin is the British Approved Name (BAN) and the United States Adopted Name (USAN).{{cite web | title=Cephalexin [USAN:BAN] | website=ChemIDplus | url=https://chem.nlm.nih.gov/chemidplus/rn/15686-71-2 | access-date=25 September 2022 | archive-date=29 January 2022 | archive-url=https://web.archive.org/web/20220129041851/https://chem.nlm.nih.gov/chemidplus/rn/15686-71-2 | url-status=live }} Brand names for cefalexin include Keflex, Acfex, Cephalex, Ceporex, L-Xahl, Medoxine, Ospexin, Torlasporin, Bio-Cef, Panixine DisperDose, and Novo-Lexin.{{cite web | title=Cefalexin International | website=Drugs.com | date=3 February 2020 | url=https://www.drugs.com/international/cefalexin.html | access-date=8 February 2020 | archive-date=29 May 2016 | archive-url=https://web.archive.org/web/20160529145832/http://www.drugs.com/international/cefalexin.html | url-status=live }}{{cite web |title=Cephalexin (Oral Route) Description and Brand Names |url=https://www.mayoclinic.org/drugs-supplements/cephalexin-oral-route/description/drg-20073325 |website=May Clinic |publisher=Mayo Foundation for Medical Education and Research |access-date=14 November 2022}}
Veterinary uses
= Dogs =
According to Plumb's Veterinary Medication Guides, cefalexin can be used in treating skin, respiratory tract, and urinary tract infections. Specifically, it can treat pyoderma in dogs.{{cite web | vauthors = Gollakner R |title=Cephalexin |url=https://vcahospitals.com/know-your-pet/cephalexin#:~:text=Cephalexin%20(brand%20names%20Rilexine%C2%AE,other%20types%20of%20skin%20infections. |website=VCA Animal Hospitals |publisher=Affiliate of Mars Inc. |access-date=14 November 2022}} The U.S. Food and Drug Administration (FDA) has approved it for use in humans and dogs but not for other species. Like other drugs approved for human use, cefalexin may be prescribed by veterinarians for animals in certain situations.{{cite web |title=Frequently Asked Questions about Animal Drugs |website=Food and Drug Administration |date=17 April 2024 |url=https://www.fda.gov/animal-veterinary/safety-health/frequently-asked-questions-about-animal-drugs#people |access-date=9 June 2024}}
Cefalexin (Lexylan) is indicated for the treatment of cattle, dogs, and cats in the European Union.{{cite web | title=Lexylan Product information | website=Union Register of veterinary medicinal products | date=10 April 2024 | url=https://ec.europa.eu/health/documents/community-register/html/v308.htm | access-date=17 June 2024}}
References
{{Reflist}}
{{Cell wall disruptive antibiotics}}
{{Portal bar | Medicine}}
{{Authority control}}
Category:Cephalosporin antibiotics
Category:Drugs developed by Eli Lilly and Company
Category:World Health Organization essential medicines