Oxacillin

KEY POINTS

Oxacillin is an anti-staphylococcal penicillin aka penicillinase-resistant penicillin
- This class is sometimes referred to as the “CONDOM” drugs
  - CONDOM = cloxacillin, oxacillin, nafcillin, dicloxacillin, oxacillin (again), methicillin
  - Not common to use this term in practice, but helps for studying
- Works by interfering with cell wall synthesis in susceptible bacteria via penicillin binding proteins (PBPs)
Oxacillin and nafcillin are the injectable drugs in this class
- They are very similar and typically an institution will carry whichever is cheaper
  - Although relatively old and available in generic formulations, these drugs are commonly high-cost
Like cefazolin (Ancef), oxacillin is a go-to drug for treating methicillin-sensitive Staphylococcus aureus (MSSA) infections
- Infrequently used for non-MSSA infections
Common dose in adults is 2gm IV every 4-6 hours
- May be given as a continuous infusion (e.g., 10g or 12g administered over 20 or 24 hours)
- No need to adjust doses for renal insufficiency
Beware AST/ALT elevations, interstitial nephritis (reason methicillin was removed from the market), sodium load (particularly in elderly or patients with congestive heart failure) and hypersensitivity reaction

RESOURCES