Cefalexin

Cefalexin

Systematic (IUPAC) name
(6R,7R)-7-{[(2R)-2-amino-2-phenylacetyl]amino}- 3-methyl-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene- 2-carboxylic acid
Clinical data
AHFS/Drugs.com	International Drug Names
Pregnancy cat.	A(AU) B(US)
Legal status	Prescription Only (S4) (AU) POM (UK)
Routes	Oral
Pharmacokinetic data
Bioavailability	Well absorbed
Protein binding	15%
Metabolism	80% excreted unchanged in urine within 6 hours of administration
Half-life	For an adult with normal renal function, the serum half-life is 0.5-1.2 hours[1]
Excretion	Renal
Identifiers
CAS number	15686-71-2 Y
ATC code	J01DB01 QJ51DA01
PubChem	CID 2666
DrugBank	APRD00250
ChemSpider	25541 Y
UNII	5SFF1W6677 Y
KEGG	D00263 Y
ChEBI	CHEBI:3534 Y
ChEMBL	CHEMBL1727 Y
Chemical data
Formula	C16H17N3O4S
Mol. mass	347.39 g/mol
SMILES	eMolecules & PubChem
InChI InChI=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 Y Key:ZAIPMKNFIOOWCQ-UEKVPHQBSA-N Y
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Cefalexin (INN) or more commonly cephalexin ( /ˌsɛfəˈlɛksɨn/) is a first-generation cephalosporin antibiotic introduced in 1967 by Eli Lilly and Company.^[2][3] It is an orally administered agent with a similar antimicrobial spectrum to the intravenous agents cefalotin and cefazolin. It was first marketed as Keflex (Lilly), and now is also sold under several other trade names.^[2]

As of 2008, cefalexin was the most popular cephalosporin antibiotic in the United States, with more than 25 million prescriptions of its generic versions alone, for US$255 million in sales (though less popular than two other antibiotics, amoxicillin and azithromycin, each with 50 million prescriptions per year).^[4][5]

Medical uses

Cefalexin is used to treat a number of infections including: otitis media, streptococcal pharyngitis, bone and joint infections, pneumonia, cellulitis, and urinary tract infections.^[6] It may be used to prevent bacterial endocarditis.^[6]

Infections

In addition to being a rational first-line treatment for cellulitis, it is a useful alternative to penicillins in patients with penicillin hypersensitivity. In patients with mild or questionable history of penicillin allergy, cephalasporins are now thought to be relatively safe.^[7] Caution should always be taken when prescribing cephalosporins to those with strong history of true penicillin hypersensitivity, however, because cefalexin and other first-generation cephalosporins are known to have a modest cross-allergy in patients with penicillin hypersensitivity.

Cefalexin may not be effective against bacteria that incorporate a gene for beta-lactamase on their R-plasmid as the beta-lactam ring is present in the chemical structure of cephalosporin derivatives.^{[citation needed]}

Formulations

Cefalexin is marketed by generic pharmaceutical manufacturers under a wide range of brand names, including: Apo-Cephalex, Biocef, Cefanox, Ceforal, Cephabos, Cephalexin, Cephorum, Ceporex, Cilex, Ialex, Ibilex, Kefexin, Keflet, Keflex, Rekosporin, Keforal, Keftab, Keftal, Lopilexin, Larixin, Novo-Lexin, Ospexin, Tenkorex, Zephalexin, Panixine Disperdose, and Sporidex.

A version of Keflex 750 mg capsules is marketed for twice-daily dosage, to improve compliance. However, it is not a sustained release formulation, and since it is more expensive than the older strengths, some physicians prescribe three 250 mg capsules to be taken twice daily, as a cheaper alternative.^{[citation needed]}

In Finland, cefalexin is marketed under several names. Orion markets Kefexin.^[8][9]

Adverse effects

Adverse effects from cefalexin include diarrhea, dizziness, agitation, headache, indigestion, joint pain, stomach pain (usually mild) and tiredness. The drug can also cause yellowing of the eyes or skin; red, blistered, swollen or peeling skin; unusual bruising or bleeding; decreased urination; severe cramps and confusion. An allergic reaction to this medicine is unlikely. Symptoms of an allergic reaction include rash, itching, swelling, or trouble breathing.

References

1. ^ McEvoy, G.K. (ed.). American Hospital Formulary Service - Drug Information 95. Bethesda, MD: American Society of Hospital Pharmacists, Inc., 1995 (Plus Supplements 1995)., p. 166
2. ^ ^{a b} Sweetman, Sean C., ed (2009). "Antibacterials". Martindale: The complete drug reference (36th ed.). London: Pharmaceutical Press. pp. 218–9. ISBN 978-0-85369-840-1. 
3. ^ Sneader, Walter (2005). "Cephalosporin analogues". Drug discovery: a history. New York: Wiley. pp. 324. ISBN 0-471-89980-1. http://books.google.com/books?id=mYQxRY9umjcC&pg=PA324. Retrieved 2009-06-26. 
4. ^ "2008 Top 200 generic drugs by total prescriptions" PDF (332.8 KB). Drug Topics (May 26, 2009). Retrieved on July 24, 2009.
5. ^ "2008 Top 200 generic drugs by retail dollars" PDF (399.4 KB). Drug Topics (May 26, 2009). Retrieved on July 24, 2009.
6. ^ ^{a b} "Cephalexin". The American Society of Health-System Pharmacists. http://www.drugs.com/monograph/cephalexin.html. Retrieved 3 April 2011. 
7. ^ Pichichero ME (March 2007). "Use of selected cephalosporins in penicillin-allergic patients: a paradigm shift". Diagnostic Microbiology and Infectious Disease 57 (3 Suppl): 13S–18S. doi:10.1016/j.diagmicrobio.2006.12.004. PMID 17349459. 
8. ^ http://spc.nam.fi/indox/nam/html/nam/humpil/2/244412.pdf.
9. ^ http://spc.nam.fi/indox/nam/html/nam/humspc/2/244362.shtml.

External links

• U.S. National Library of Medicine: Drug Information Portal - Cephalexin