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Cloxacillin ball-and-stick.png
Clinical data
Trade names Cloxapen, others
AHFS/ Micromedex Detailed Consumer Information
  • US: B (No risk in non-human studies)
Routes of
by mouth, IM
ATC code
Pharmacokinetic data
Bioavailability 37 to 90%
Protein binding 95%
Biological half-life 30 minutes to 1 hour
Excretion kidney and biliary
CAS Number
PubChem CID
ECHA InfoCard 100.000.468
Chemical and physical data
Formula C19H18ClN3O5S
Molar mass 435.88 g/mol
3D model (Jmol)

Cloxacillin is an antibiotic useful for the treatment of a number of bacterial infections. This includes impetigo, cellulitis, pneumonia, septic arthritis, and otitis externa.[1] It is not effective for methicillin-resistant Staphylococcus aureus (MRSA).[2] It is used by mouth and by injection.[1]

Side effects include nausea, diarrhea, and allergic reactions including anaphylaxis.[1] Clostridium difficile diarrhea may also occur.[2] It is not recommended in people who have previously had a penicillin allergy. Use during pregnancy appears to be relatively safe.[1] Cloxacillin is in the penicillin family of medications.[2]

Cloxacillin was patented in 1960 and approved for medical use in 1965.[3] It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system.[4] The wholesale cost in the developing world is about 0.16 USD per day for the pills.[5] It is not commercially available in the United States.[2]

Mechanism of action[edit]

It is semisynthetic and in the same class as penicillin. Cloxacillin is used against staphylococci that produce beta-lactamase, due to its large R chain, which does not allow the beta-lactamases to bind. This drug has a weaker antibacterial activity than benzylpenicillin, and is devoid of serious toxicity except for allergic reactions.

Society and culture[edit]

Cloxacillin was discovered and developed by Beecham.[6]

It is sold under a number of trade names, including Cloxapen, Cloxacap, Tegopen and Orbenin.

See also[edit]


  1. ^ a b c d WHO Model Formulary 2008 (PDF). World Health Organization. 2009. pp. 110, 586. ISBN 9789241547659. Retrieved 8 December 2016. 
  2. ^ a b c d "Cloxacillin (Professional Patient Advice)". Retrieved 10 December 2016. 
  3. ^ Fischer, Janos; Ganellin, C. Robin (2006). Analogue-based Drug Discovery. John Wiley & Sons. p. 490. ISBN 9783527607495. 
  4. ^ "WHO Model List of Essential Medicines (19th List)" (PDF). World Health Organization. April 2015. Retrieved 8 December 2016. 
  5. ^ "Cloxacillin Sodium". International Drug Price Indicator Guide. Retrieved 8 December 2016. 
  6. ^ David Greenwood (2008). Antimicrobial drugs: chronicle of a twentieth century medical triumph. Oxford University Press US. pp. 124–. ISBN 978-0-19-953484-5. Retrieved 18 November 2010.