Editing Cefalexin (section)

==Pharmacology==

===Mechanism of action===
Cefalexin is a β-lactam antibiotic of the cephalosporin family.<ref name = "Botara_2006">{{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 }}</ref>  It is [[bactericidal]] and acts by inhibiting synthesis of the [[peptidoglycan]] layer of the bacterial cell wall.<ref name="Fisher_2005">{{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 }}</ref> 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 [[Penicillin binding proteins|PBP]], which is essential for the synthesis of the cell wall.<ref name="Fisher_2005"/> It is most active against [[gram-positive cocci]], and has moderate activity against some [[gram-negative bacilli]].<ref name=AHFS2014/> However, some bacterial cells have the enzyme [[beta lactamase|β-lactamase]], which hydrolyzes the β-lactam ring, rendering the drug inactive. This contributes to [[Antimicrobial resistance|antibacterial resistance]] towards cefalexin.<ref name="pmid20065329">{{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 }}</ref>

===Pharmacokinetics===
Cefalexin is rapidly and almost completely absorbed from the [[gastrointestinal tract]] with [[oral administration]].<ref name="Keflex-Label" /> Absorption is slightly reduced when it is taken with food and the medication can be taken without regard for meals.<ref name="Keflex-Label" /> Peak levels of cefalexin occur about 1&nbsp;hour after administration.<ref name="Keflex-Label" /> Maximal levels of cefalexin increase approximately linearly over a dose range of 250 to 1,000&nbsp;mg.<ref name="Keflex-Label" />

Like most other cephalosporins, cefalexin is not [[metabolism|metabolized]] or otherwise inactivated in the body.<ref name="GraysonCosgrove2017">{{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}}</ref><ref name="Skidmore-Roth2015">{{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}}</ref>

The [[elimination half-life]] of cefalexin is approximately 30 to 60&nbsp;minutes in people with normal renal function.<ref name="Skidmore-Roth2015" /><ref name="Keflex-Label" /> Therapeutic levels of cefalexin with oral administration are maintained for 6 to 8&nbsp;hours.<ref name="Keflex-Label">{{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}}</ref> More than 90% of cefalexin is excreted unchanged in the urine within 8&nbsp;hours.<ref name="Keflex-Label" />