Cefixime Adult Dosing
The recommended adult dose of cefixime is 400 mg daily, which is also the maximum daily dose for patients with normal renal function. 1
Standard Dosing Regimen
The FDA-approved dosing for adults is straightforward:
- Standard dose: 400 mg once daily (can be given as a single 400 mg tablet or capsule)
- Maximum daily dose: 400 mg per day
- Administration: May be taken with or without food 1
Special Considerations
Gonococcal Infections
For uncomplicated cervical or urethral gonococcal infections, a single oral dose of 400 mg is recommended 1. However, cefixime is no longer recommended as first-line therapy for gonorrhea due to rising resistance patterns, particularly elevated minimum inhibitory concentrations (MICs) observed in surveillance data 2. The CDC guidelines from 1998-2006 previously recommended cefixime 400 mg as a treatment option 3, 4, 5, but more recent evidence shows concerning resistance trends.
Renal Impairment Dosing
Dose adjustments are required only when creatinine clearance falls below 60 mL/min 1:
- CrCl ≥60 mL/min: Normal dose (400 mg daily)
- CrCl 21-59 mL/min (or on hemodialysis): 260 mg daily (13 mL of 100 mg/5 mL suspension or 6.5 mL of 200 mg/5 mL suspension)
- CrCl ≤20 mL/min (or on peritoneal dialysis): 172 mg daily (8.6 mL of 100 mg/5 mL suspension or 4.4 mL of 200 mg/5 mL suspension)
Neither hemodialysis nor peritoneal dialysis removes significant amounts of cefixime from the body 1, 6, so supplemental dosing post-dialysis is not required.
Pharmacokinetic Rationale
The 400 mg maximum dose is supported by pharmacokinetic data showing:
- Bioavailability: Approximately 50% after oral administration 6
- Peak serum concentrations: 2.7-4.4 mg/L achieved 3-4 hours after a 400 mg dose 7, 8
- Elimination half-life: 3-4 hours, allowing for once-daily dosing 6, 9
- Protein binding: 70% 6
- Excretion: 40% renal (unchanged), 60% hepatic 6
Plasma concentrations increase linearly but not proportionally to dose, and no significant accumulation occurs with repeated daily administration 6, 8. The 400 mg dose provides adequate tissue penetration for most susceptible infections 6, 9.
Duration of Therapy
- Most infections: Typically 7-14 days depending on infection type and severity
- Streptococcus pyogenes infections: Minimum 10 days required 1
- Uncomplicated gonorrhea: Single dose (though no longer first-line) 1
Important Caveats
Do not exceed 400 mg daily in adults with normal renal function. Higher doses have not been studied for safety or efficacy and may increase the risk of adverse effects without additional therapeutic benefit. The drug's pharmacokinetics show that doubling the dose does not proportionally increase serum concentrations 6.
For severe infections requiring higher cephalosporin levels, consider parenteral alternatives like ceftriaxone rather than exceeding the maximum oral cefixime dose.