Cefixime Dosing: 200mg BID vs 400mg Once Daily
No, you should not substitute cefixime 200mg twice daily for 400mg once daily—the total daily dose of 400mg is what matters for efficacy, and both regimens deliver the same total dose, making them therapeutically equivalent for most indications. 1
FDA-Approved Dosing
The FDA label for cefixime explicitly states that the recommended adult dose is 400mg daily, which may be administered either as:
- A single 400mg dose once daily, OR
- In divided doses 1
For pediatric patients, the recommended dose of 8 mg/kg/day "may be administered as a single daily dose or may be given in two divided doses, as 4 mg/kg every 12 hours" 1. This confirms that divided dosing is an acceptable alternative to once-daily administration.
Pharmacokinetic Rationale
Cefixime's 3-hour elimination half-life permits both once-daily and twice-daily dosing regimens 2, 3. Clinical trials have demonstrated comparable efficacy with both approaches:
- Studies show that 200-400mg daily administered as either a single dose or in 2 divided doses achieves comparable clinical and bacteriological efficacy 2
- The key factor is achieving the total daily dose of 400mg, not the frequency of administration 4
Important Caveat: Gastrointestinal Tolerability
The twice-daily 200mg regimen (BID) may actually be preferable to 400mg once daily due to better gastrointestinal tolerance 4. A controlled study specifically found that:
- Once-daily 400mg dosing showed a higher incidence of gastrointestinal adverse effects compared to 200mg twice daily 4
- The recommendation is to administer the daily dose in two divided doses to minimize GI side effects 4
- Diarrhea and stool changes occur in up to 20% of patients and are the most significant adverse reactions 3
Context-Specific Considerations
For Gonorrhea Treatment
This equivalence does NOT apply to gonorrhea treatment, where specific single-dose regimens are mandated:
- Cefixime for gonorrhea requires a single 400mg dose (not divided) 5, 6, 7, 1
- Cefixime is no longer first-line for gonorrhea due to rising resistance 5, 6, 7
- When used as an alternative (when ceftriaxone unavailable), it must be combined with azithromycin 1g or doxycycline 100mg BID × 7 days 5, 6, 7
- A test-of-cure is mandatory at 1 week 5, 7
For Other Infections (UTI, Respiratory Tract)
For urinary tract infections and respiratory infections, both 200mg BID and 400mg once daily are acceptable 2, 4, 8:
- Uncomplicated UTI: Either regimen is effective 2, 4
- Respiratory tract infections: Both dosing schedules show comparable efficacy 2, 8
- Treatment duration should be at least 10 days for Streptococcus pyogenes infections 1
Clinical Recommendation
For non-gonococcal infections, cefixime 200mg twice daily is therapeutically equivalent to 400mg once daily and may be preferred due to better GI tolerability 4. The choice between regimens can be based on:
- Patient preference for dosing convenience (once daily) versus tolerability (twice daily)
- GI sensitivity: Use 200mg BID if patient has history of antibiotic-associated diarrhea 4
- Compliance concerns: Once-daily dosing may improve adherence in some patients 2, 3
The substitution is appropriate as long as the total daily dose remains 400mg and the indication is not gonorrhea (which requires single-dose therapy) 1.