Can cefoxitin be administered intramuscularly (IM)?

Cefoxitin Administration Routes: Intramuscular Option

Yes, cefoxitin can be administered intramuscularly (IM) for mild to moderate infections, providing an alternative to intravenous administration when the IV route is not appropriate or available.

Evidence Supporting IM Administration

• Cefoxitin can be effectively administered via the intramuscular route for infections of mild to moderate severity, with clinical studies showing cure or improvement in the majority of treated patients 1
• When administered intramuscularly, cefoxitin is typically diluted in lidocaine (0.5% or 1.0%) to minimize injection discomfort, with 96% of patients reporting no pain with this preparation method 1
• Clinical efficacy with IM cefoxitin has been demonstrated in various infection types, including skin/soft tissue infections, lower respiratory tract infections, and urinary tract infections 1

Dosing Guidelines for IM Administration

• For adults, the standard dosing for cefoxitin when administered intravenously is 200 mg/kg/day in three divided doses (maximum 12 g/day) 2
• For children aged 1 month and above, the recommended dosing is 150 mg/kg/day in 3-4 divided doses (maximum 12 g/day) 2
• When administered intramuscularly for mild to moderate infections, the typical adult dose is 1 g diluted in 1 ml of 0.5% or 1.0% lidocaine four times daily 1

Clinical Applications for IM Cefoxitin

• IM cefoxitin is particularly useful in three scenarios:

  1. Initial treatment of mild to moderate infections
  2. Continuation therapy after initial IV treatment when the intravenous route is no longer necessary or appropriate
  3. Treatment of polymicrobial infections such as ulcers on ischemic extremities or in diabetic patients 1

• Similar to other cephalosporins like ceftriaxone, which can be administered IM for certain infections, cefoxitin provides flexibility in treatment settings where IV access is limited 3

Monitoring and Safety Considerations

• Routine toxicity monitoring (FBC, U&Es, LFTs) should be performed intermittently throughout treatment with cefoxitin, regardless of administration route 2
• Common adverse effects to monitor include hypersensitivity reactions, maculopapular rash, urticaria, transient increases in liver enzymes, and potential hematological effects like leucopenia and thrombocytopenia 2
• Serious but rare adverse effects include seizures, acute renal failure, and toxic nephropathy 2

Important Drug Interactions

• Cefoxitin may interact with:
  • Aminoglycosides: increased risk of nephrotoxicity
  • Anticoagulants: increased INR with warfarin
  • Furosemide: increased risk of nephrotoxicity
  • Probenecid: reduced renal excretion of cefoxitin, resulting in increased and prolonged serum levels 2

Practical Considerations

• Cefoxitin is not licensed in the UK but is available in other countries 2
• When using the IM route, proper dilution with lidocaine is essential to minimize injection site discomfort 1
• For patients requiring long-term therapy, the IM route may be preferable to prolonged IV access, particularly in outpatient settings 1, 4