Cefixime Dosing in a 2-Month-Old Infant
Cefixime is FDA-approved for pediatric patients 6 months or older at 8 mg/kg/day, and there is insufficient safety and efficacy data to recommend its use in a 2-month-old infant. 1
Critical Age Limitation
- The FDA-approved lower age limit for cefixime is 6 months of age, making this drug inappropriate for a 2-month-old infant 1
- Clinical pharmacokinetic studies in infants have only included patients as young as 2 months, but these were observational studies, not controlled trials establishing safety 2, 3
- The elimination half-life in young infants (2-22 months) ranges from 2.6 to 5.6 hours, which is longer than in older children, raising concerns about drug accumulation in younger infants 3
Alternative Third-Generation Cephalosporins for This Age Group
For a 2-month-old infant requiring a third-generation cephalosporin, use cefotaxime or ceftriaxone instead:
Cefotaxime (Preferred for 2-Month-Olds)
- Dose: 150 mg/kg/day divided every 8 hours for infants >1 month of age 4
- This provides 50 mg/kg per dose every 8 hours 5
- Cefotaxime has well-established safety and pharmacokinetic data in neonates and young infants 6
Ceftriaxone (Alternative)
- Dose: 50-75 mg/kg/day given every 24 hours for infants >7 days of age and >2000 g 4
- Critical contraindication: Do not use in hyperbilirubinemic infants due to risk of kernicterus from bilirubin displacement 4
- At 2 months of age, hyperbilirubinemia is less common but must be ruled out before use 4
Common Pitfalls to Avoid
- Never extrapolate pediatric dosing below the FDA-approved age range without specific neonatal/infant pharmacokinetic data 1
- Avoid ceftriaxone in any infant with jaundice or elevated bilirubin, regardless of age 4
- Do not use oral cephalosporins for serious infections in young infants who may have unpredictable absorption 3
Clinical Context
- If this question arose because of a specific infection (e.g., UTI, respiratory infection), parenteral therapy with cefotaxime is strongly preferred over any oral agent in a 2-month-old 4, 6
- For outpatient management of mild infections, amoxicillin or amoxicillin-clavulanate would be more appropriate oral options than cefixime at this age 7