Meropenem Dosing for Meningitis
For infants and children with bacterial meningitis, administer meropenem at 40 mg/kg (up to a maximum of 2 grams) every 8 hours, while adults should receive 2 grams every 8 hours. 1, 2
Pediatric Dosing
Infants and Children ≥3 Months of Age
- Administer 40 mg/kg every 8 hours (maximum 2 grams per dose) for bacterial meningitis 1, 2
- For children weighing over 50 kg, give the adult dose of 2 grams every 8 hours 2
- Infuse over 15-30 minutes, or administer as a bolus injection over 3-5 minutes (though limited safety data exist for 40 mg/kg bolus dosing) 2
Infants <3 Months of Age
For complicated intra-abdominal infections (meningitis dosing not specifically established in this age group): 2
- Infants <32 weeks gestational age (GA) and postnatal age (PNA) <2 weeks: 20 mg/kg every 12 hours
- Infants <32 weeks GA and PNA ≥2 weeks: 20 mg/kg every 8 hours
- Infants ≥32 weeks GA and PNA <2 weeks: 20 mg/kg every 8 hours
- Infants ≥32 weeks GA and PNA ≥2 weeks: 30 mg/kg every 8 hours
Adult Dosing
- Administer 2 grams every 8 hours for bacterial meningitis 1
- Infuse over 15-30 minutes, or give as a bolus injection over 3-5 minutes 2
Renal Dose Adjustments (Adults)
Critical to prevent neurotoxicity: 3, 2
- CrCl >50 mL/min: No adjustment needed (2 g every 8 hours)
- CrCl 26-50 mL/min: 2 g every 12 hours
- CrCl 10-25 mL/min: 1 g every 12 hours
- CrCl <10 mL/min: 1 g every 24 hours
Renal impairment is the primary risk factor for meropenem neurotoxicity, with trough concentrations >64 mg/L associated with neurotoxicity in 50% of patients. 3
Evidence Supporting High-Dose Regimen
The 40 mg/kg pediatric dose is supported by pharmacokinetic/pharmacodynamic analysis showing that this higher dose (compared to 20 mg/kg) is necessary to achieve adequate CSF penetration and bactericidal activity against resistant pathogens like penicillin-resistant Streptococcus pneumoniae and Pseudomonas aeruginosa. 4
- Patients achieving clinical cure demonstrated at least 75.3% time above MIC in CSF 4
- The flat CSF concentration-time profile means prolonged infusion offers minimal benefit over standard infusion, but dose escalation significantly improves target attainment 4
Clinical Context and Indications
Meropenem is FDA-approved for pediatric bacterial meningitis (≥3 months) caused by: 2
- Haemophilus influenzae
- Neisseria meningitidis
- Penicillin-susceptible Streptococcus pneumoniae
However, meropenem is NOT first-line therapy for typical meningococcal or pneumococcal meningitis—third-generation cephalosporins (ceftriaxone/cefotaxime) remain preferred. 1, 3
When to Consider Meropenem
- Suspected ESBL-producing gram-negative organisms (particularly Enterobacteriaceae) 1, 5, 3
- Post-neurosurgical meningitis with resistant organisms 6
- Failure of first-line therapy or documented resistance 5
Treatment Duration
Duration depends on the identified pathogen: 5, 7
- Enterobacteriaceae: 21 days
- Streptococcus pneumoniae: 10-14 days (10 days if stable, up to 14 if slow response)
- Haemophilus influenzae: 10 days
- Neisseria meningitidis: 5 days (if recovered)
- Listeria monocytogenes: 21 days
Common Pitfalls to Avoid
- Do not use meropenem as first-line for typical meningococcal infections when ceftriaxone/cefotaxime are appropriate—it offers no advantage 3
- Never underdose in pediatric meningitis—20 mg/kg is insufficient; 40 mg/kg is required for adequate CSF penetration 4
- Always adjust for renal impairment to prevent neurotoxicity (seizures can occur with accumulation) 3, 2
- Avoid premature discontinuation—gram-negative organisms typically require 21 days of therapy 5, 7
- Do not use vancomycin alone if adding for resistant pneumococci—always combine with beta-lactam therapy due to poor CSF penetration 5, 7
Safety Profile
Meropenem has a lower seizure risk than imipenem (16% relative pro-convulsive activity compared to penicillin G), making it safer for CNS infections. 3 However, seizures remain a concern with renal impairment or excessive dosing. 2