What is the proper preparation and administration of Cefoxitin (Cephamycin antibiotic)?

Cefoxitin Preparation and Administration

Cefoxitin must be reconstituted with Sterile Water for Injection and administered intravenously, with doses over 2 grams requiring dilution in sodium chloride 0.9% or glucose 5% for infusion. 1, 2

Reconstitution Process

For Pharmacy Bulk Package (100g bag):

• Add 930 mL of Sterile Water for Injection through the reconstitution port to achieve a concentration of 100 mg/mL (1 gram per 10 mL) 2
• Complete the entire reconstitution and preparation process within 4 hours of initial entry 2
• Place the bag on a flat surface and mix for at least 15 minutes by rocking gently side to side—avoid vigorous shaking to prevent leakage 2
• Inspect the solution to ensure it is clear, colorless to pale yellow, and free of particulate matter before use 2

For Individual Doses:

• Transfer 10 mL of reconstituted solution (containing 1 gram) into infusion bags containing 50 mL of compatible diluent 2
• Compatible diluents include Sodium Chloride Injection USP or 5% Dextrose Injection USP 2

Administration Guidelines

Intravenous Infusion (Preferred Route):

• Administer doses of 1-2 grams by intermittent IV infusion over an appropriate period through existing IV tubing 2
• Temporarily discontinue other IV solutions at the same site during cefoxitin infusion 2
• Never mix cefoxitin with aminoglycoside solutions (gentamicin, tobramycin, amikacin) in the same container due to potential interaction 2
• Aminoglycosides may be administered separately to the same patient 2

Intramuscular Administration (Alternative):

• For mild to moderate infections, cefoxitin 1 gram can be diluted in 1 mL of 0.5% or 1.0% lidocaine for IM injection 3
• This route is appropriate when IV access is limited or for continuation therapy after initial IV treatment 3
• IM administration was well-tolerated in 96% of patients in clinical studies 3

Dosing by Patient Population

Adults:

• Standard dose: 200 mg/kg/day in three divided doses (maximum 12 g/day) IV 1, 4
• For serious infections like M. abscessus: up to 12 g/day in divided doses 1
• Typical individual doses: 1-2 grams every 6-8 hours 1

Pediatric Patients (≥1 month):

• Standard dose: 150 mg/kg/day in 3-4 divided doses (maximum 12 g/day) IV 1, 5, 4
• For a 14 kg child: total daily dose = 2,100 mg/day, given as either 525 mg every 6 hours or 700 mg every 8 hours 5

Stability and Storage

• Reconstituted solution is stable for 18 hours at room temperature 2
• Refrigerated reconstituted solution (5°C or 41°F) is stable for 48 hours 2
• Any unused portion from the pharmacy bulk package must be discarded after 4 hours from initial entry 2
• Discard any unused diluted solutions after the stability periods mentioned above 2

Critical Monitoring Requirements

Renal Function:

• Monitor renal function closely, especially when combining with aminoglycosides or furosemide due to increased nephrotoxicity risk 1, 5, 4
• Adjust dose or extend dosing interval if creatinine clearance is reduced 5
• Use caution in severe renal impairment or end-stage renal disease 1

Routine Laboratory Monitoring:

• Perform complete blood count, renal function tests (U&Es), and liver function tests (LFTs) intermittently throughout treatment 1, 4
• Monitor for eosinophilia (occurred in 7% of patients), leucopenia, and thrombocytopenia 1, 4, 3

Drug Interactions to Monitor:

• Probenecid reduces renal excretion of cefoxitin, resulting in increased and prolonged serum levels 1, 4
• Warfarin: monitor INR closely as cefoxitin increases anticoagulant effect 1, 4

Common Pitfalls to Avoid

• Do not use if particulate matter or discoloration is present after reconstitution 2
• Never add cefoxitin to aminoglycoside solutions in the same container—this is a critical incompatibility 2
• Do not exceed the 4-hour preparation window for pharmacy bulk packages to prevent contamination 2
• Avoid vigorous shaking during reconstitution as this may cause bag leakage 2
• Watch for thrombophlebitis at injection sites, the most common adverse effect 1, 6