Alcephin
(cefalexin 125mg)

Drug Effects

Synonyms(It is also Known As)


Cefalexin Sodium, Cephalexin 1-hydrate, Cephalexin hydrate, Cephalexin monohydrate, Cephalexine

Chemical Formula


C16H17N3O4

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

Usage


Cefalexin or more commonly cephalexin is a first-generation cephalosporin antibiotic introduced in 1967 by Eli Lilly and Company. 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 is marketed under several other trade names.

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

Adverse Effect


Pain at inj site; hypersensitivity; GI disturbances; eosinophilia, neutropenia, leucopenia, thrombocytopenia.

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Potentially Fatal: Anaphylactic reactions; nephrotoxicity

Mechanism Action


Cefalexin binds to one or more of the penicillin-binding proteins (PBPs) which inhibits the final transpeptidation step of peptidoglycan synthesis in bacterial cell wall, thus inhibiting biosynthesis and arresting cell wall assembly resulting in bacterial cell death.

Precaution


Caution should be exercised in patients with history of stomach or bowel problems (eg, inflammation), blood clotting problems, kidney or liver problems, any allergy, who are taking other medications, elderly, children, during pregnancy and breast feeding. 

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It may cause dizziness, do not drive a car or operate machinery while taking this medication. 

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It may reduce platelet counts, avoid injury or bruising.

Drug Interaction


Probenecid produces higher and prolonged serum levels.

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Potentially Fatal: Increased nephrotoxicity with aminoglycosides and furosemide.

Pregnancy Category


Category B: Either animal-reproduction studies have not demonstrated a foetal risk but there are no controlled studies in pregnant women or animal-reproduction studies have shown an adverse effect (other than a decrease in fertility) that was not confirmed in controlled studies in women in the 1sttrimester (and there is no evidence of a risk in later trimesters).

Absorption


Almost completely absorbed from the GI tract with peak plasma concentrations after 1 hr (oral); may be delayed if taken with food.

Distribution


Widely distributed but does not penetrate the CSF; bile (therapeutic concentrations). Crosses the placenta and enters the breast milk (small amounts). Protein-binding: Up to 15%

Metabolism


Not metabolised.

Elemination


Via the urine within 6 hr by glomerular filtration and renal tubular secretion (>80% as unchanged); via the bile. May be removed by haemodialysis and peritoneal dialysis

References


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  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
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  3.   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.
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  5.  Sneader, Walter (2005). \"Cephalosporin analogues\".Drug discovery: a history. New York: Wiley. p. 324. ISBN 0-471-89980-1. Retrieved 2009-06-26.
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  7.  \"2008 Top 200 generic drugs by total prescriptions\" PDF (332.8 KB). Drug Topics (May 26, 2009). Retrieved on July 24, 2009.
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  9.  \"2008 Top 200 generic drugs by retail dollars\" PDF (399.4 KB). Drug Topics (May 26, 2009). Retrieved on July 24, 2009.
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  11.   \"Cephalexin\". The American Society of Health-System Pharmacists. Retrieved 3 April 2011.
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  13.  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.
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  15.  Haberfeld, H, ed. (2009). Austria-Codex (in German) (2009/2010 ed.). Vienna: Österreichischer Apothekerverlag.ISBN 3-85200-196-X.
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