Cefixime IV Dosing: Critical Limitation
Cefixime is NOT available in an intravenous formulation and should never be administered IV. Cefixime is exclusively an oral cephalosporin antibiotic, available only as tablets or oral suspension 1, 2, 3, 4.
Available Formulation and Route
- Cefixime is administered orally only as cefixime trihydrate or the prodrug cefixime proxetil 2, 4
- The drug is absorbed from the gastrointestinal tract and reaches adequate serum levels exceeding MIC for most susceptible organisms 2, 4
- No parenteral (IV or IM) formulation exists for cefixime 4
Standard Oral Dosing
Adult Dosing (Normal Renal Function)
- Standard dose: 200-400 mg orally once daily or divided into two doses 4
- The 3-hour elimination half-life permits once or twice daily administration 4
- Most infections respond to 200 mg twice daily or 400 mg once daily 4
Pediatric Dosing
- 8 mg/kg/day orally in single or two divided doses 2, 4
- Maximum daily dose should not exceed adult dosing 4
Renal Impairment Adjustments
Moderate Renal Impairment (CrCl 30-60 mL/min)
- Standard dosing can be used with monitoring 1, 3
- Half-life increases to approximately 4.15 hours 1
- Peak levels occur at 6 hours post-dose 1
Severe Renal Impairment (CrCl 10-30 mL/min)
- Dose reduction required: 200 mg once daily or 100 mg twice daily 1, 3
- Half-life prolonged to 11-14 hours 1, 3
- Drug accumulation occurs with standard dosing 3
- Peak serum levels occur at 8 hours and remain elevated at 24 hours 1
End-Stage Renal Disease (CrCl <10 mL/min)
- Maximum dose: 200 mg once daily 3
- Significant accumulation occurs due to renal excretion pathway 3
- Apparent total body clearance and renal clearance decrease proportionally with declining renal function 3
Alternative IV Cephalosporins
If parenteral therapy is required, consider these alternatives based on the clinical scenario:
Third-Generation Cephalosporins (IV)
- Ceftriaxone: 1-2 g IV every 12-24 hours for most infections 5, 6
- Cefotaxime: 200 mg/kg/day IV divided every 6 hours (pediatric) or 1-2 g every 6-8 hours (adult) 5
- Ceftazidime: 100-150 mg/kg/day IV divided every 8 hours for Pseudomonas coverage 5
Fourth-Generation Cephalosporin (IV)
- Cefepime: 2 g IV every 8 hours for severe infections or Pseudomonas 5, 7, 8
- For critically ill patients with normal renal function, higher doses may be required initially 7
- Extended infusions (3-4 hours) optimize pharmacodynamics for high-MIC organisms 7, 8
Sequential IV-to-Oral Therapy Strategy
For severe infections initially requiring IV therapy, consider:
- Start with IV ceftriaxone 2 g daily for 4 days, then switch to oral cefixime 200 mg twice daily for completion of therapy 9
- This approach demonstrated 74.3% clinical cure and bacteriologic eradication in severe upper urinary tract infections 9
- Sequential therapy is appropriate after clinical improvement, excluding patients with urological abnormalities or vascular complications 9
Common Pitfalls to Avoid
- Never attempt IV administration of cefixime - no such formulation exists and attempting reconstitution of oral formulations for injection is dangerous 4
- Do not use standard dosing in severe renal impairment (CrCl <30 mL/min) without dose reduction 1, 3
- Cefixime has minimal activity against Staphylococcus aureus and no activity against Pseudomonas aeruginosa - choose alternative agents for these pathogens 4
- The drug is not appropriate for CNS infections due to inadequate CSF penetration 4
Cephalosporin Allergy Considerations
- Cross-reactivity between cephalosporins and penicillins occurs in approximately 1-10% of patients 5
- For patients with severe β-lactam allergy (anaphylaxis, Stevens-Johnson syndrome), avoid all cephalosporins including cefixime 5
- Alternative agents include fluoroquinolones (ciprofloxacin 10-20 mg/kg/dose orally every 12 hours) or azithromycin depending on the infection type 5
- Vancomycin is the alternative for gram-positive coverage in β-lactam allergic patients requiring parenteral therapy 5