|Trade names||Cloxapen, others|
|By mouth, IM|
|Defined daily dose||2 gm|
|AHFS/Drugs.com||Micromedex Detailed Consumer Information|
|Bioavailability||37 to 90%|
|Elimination half-life||30 minutes to 1 hour|
|Excretion||Kidney and biliary|
|Chemical and physical data|
|Molar mass||435.88 g·mol−1|
|3D model (JSmol)|
Cloxacillin is an antibiotic useful for the treatment of a number of bacterial infections. This includes impetigo, cellulitis, pneumonia, septic arthritis, and otitis externa. It is not effective for methicillin-resistant Staphylococcus aureus (MRSA). It is used by mouth and by injection.
Side effects include nausea, diarrhea, and allergic reactions including anaphylaxis. Clostridium difficile diarrhea may also occur. It is not recommended in people who have previously had a penicillin allergy. Use during pregnancy appears to be relatively safe. Cloxacillin is in the penicillin family of medications.
Cloxacillin was patented in 1960 and approved for medical use in 1965. It is on the World Health Organization's List of Essential Medicines. The wholesale cost in the developing world is about US$0.16 per day for the pills. It is not commercially available in the United States.
The defined daily dose is 2 gm by mouth and by injection. In adults the typical dose is 1 gram three times per day by mouth while in children over the age of 10 the dose is 15 mg/kg three times per day. Treatment duration for impetigo is 7 days.
The injectable form is typically given as 2 gm every 6 hours in adults, though 3 grams every 6 hours may be used for certain cases. In children over a month the dose is 25 to 50 mg/kg by injection every six hours. When the injectable form is no longer required, switching to oral cloxacillin is not recommended. People should instead be switched from the injectable treatment to either oral cephalexin or amoxicillin/clavulanic acid as soon as possible, to complete the treatment course.
For erysipelas and cellulitis, the doses of cloxacillin is usually half that for severe infections.
|Age category||Weight||By mouth||By injection over 60 min (500 mg vial, diluted in 4 ml, 125 mg/ml)|
|1 to < 3 months||4 to < 6 kg||1 ml 4 times/day|
|3 months to < 1 year||6 to < 10 kg||2 ml 4 times/day|
|1 to < 5 years||10 to < 20 kg||4 ml 4 times/day|
|5 to < 8 years||20 to < 28 kg||8 ml 4 times/day|
|8 to < 12 years||28 to < 38 kg||12 ml 4 times/day|
|≥ 12 years to 13||38 kg to < 45 kg||500 mg 3 times/day||16 ml 4 times/day|
|13 to <15 years||45 to < 55 kg||750 mg 3 times/day||16 ml 4 times/day|
|Adult||≥ 55 kg||1 gm three 3 times/day||2 gm 4 times/day|
Mechanism of action
It is semisynthetic and in the same class as penicillin. Cloxacillin is used against staphylococci that produce beta-lactamase. Cloxacillin's side chain acts as a barrier to the bacteria's enzyme and it works by breaking down the bacterial cell wall. Its absorption is reduced by food. Staph. aureus has shown resistance to cloxacillin, hence requiring alternative antibiotics.
Society and culture
Cloxacillin is sold under a number of trade names, including Cloxapen, Cloxacap, Tegopen, and commonly for veterinary use, Orbenin. It is not commercially available in the United States. It is available in Canada.
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