Dose Equivalence: Cloxacillin, Flucloxacillin, Oxacillin

• It is used to treat infections caused by susceptible (non-resistant) Gram-positive bacteria. 
• It is active against beta-lactamase-producing organisms such as Staphylococcus aureus, which would otherwise be resistant to most penicillins.

Effectiveness

• Cloxacillin, Dicloxacillin and Flucloxacillin are considered comparable and have similar dose recommendations
• Oxacillin and  Nafcillin are comparable in effectiveness and indication, however differs in dosing regimen
• example for MSSA
• Cloxacillin or flucloxacillin or dicloxacillin 25mg/kg up to 1g q6h
• Nafcillin or oxacillin 50mg/kg up to 2g q4h

Side Effects

• Flucloxacillin is reported to have higher, though rare, incidence of severe hepatic adverse effects than dicloxacillin, but a lower incidence of renal adverse effect

Pharmacokinetic

• flucloxacillin had a significantly longer serum elimination half-life
• extent of binding of flucloxacillin to the protein of human serum was similar to that of oxacillin and cloxacillin and less than that of dicloxacillin

Reference:

1. Australian Medicines Handbook 2006. Adelaide: Australian Medicines Handbook; 2006 
2. www.antimicrobe.org 
3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1820086/ 
4. https://www.nps.org.au/australian-prescriber/articles/what-to-use-instead-of-flucloxacillin