Meropenem Dosing in Bacterial Meningitis
For bacterial meningitis, administer meropenem 2 grams IV every 8 hours in adults and 40 mg/kg IV every 8 hours (maximum 2 grams per dose) in children ≥3 months of age.
Adult Dosing
The FDA-approved dose for meningitis is 2 grams IV every 8 hours, administered as a 15-30 minute infusion 1. This high-dose regimen is specifically indicated for CNS infections and differs substantially from the lower doses used for other infections (500 mg-1 gram every 8 hours for skin/soft tissue or intra-abdominal infections).
The 2016 UK Joint Specialist Societies guideline recommends meropenem 2 grams IV every 8 hours specifically for Gram-negative Enterobacteriaceae meningitis, particularly when extended-spectrum beta-lactamase (ESBL) organisms are suspected 2. This should continue for 21 days 2.
Pediatric Dosing
Children ≥3 Months of Age
- 40 mg/kg IV every 8 hours (maximum 2 grams per dose)
- Administer as 15-30 minute infusion 1
- For children >50 kg: use adult dose of 2 grams every 8 hours 3, 1
Infants <3 Months of Age
Dosing is based on gestational age (GA) and postnatal age (PNA) 1:
- Infants <32 weeks GA and 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
Administer as 30-minute infusion in this age group 1.
Renal Dose Adjustment in Adults
Dosage reduction is mandatory when creatinine clearance ≤50 mL/min 1:
| Creatinine Clearance | Dose | Interval |
|---|---|---|
| >50 mL/min | 2 grams | Every 8 hours |
| 26-50 mL/min | 2 grams | Every 12 hours |
| 10-25 mL/min | 1 gram | Every 12 hours |
| <10 mL/min | 1 gram | Every 24 hours |
Critical caveat: There is inadequate data for patients on hemodialysis or peritoneal dialysis 1. Meropenem is approximately 50% removed by intermittent hemodialysis 4. In critically ill patients with augmented renal clearance (ARC), standard dosing may be insufficient—consider therapeutic drug monitoring and dose intensification (up to 2 grams every 4 hours has been used successfully) 5.
No Pediatric Renal Adjustment Data
There is no experience in pediatric patients with renal impairment—expert consultation is essential 1.
Key Clinical Considerations
Seizure risk: Despite historical concerns with carbapenems in CNS infections, meropenem at 6 grams/day (2 grams every 8 hours) demonstrated no seizures in meningitis trials, even in patients with underlying CNS disorders 6. This favorable safety profile at high doses makes meropenem particularly suitable for meningitis 7.
Duration of therapy: Continue for 21 days when treating Gram-negative Enterobacteriaceae meningitis 2. For other pathogens, duration varies (5 days for meningococcus, 10-14 days for pneumococcus) 2.
Pharmacodynamic target: Meropenem exhibits time-dependent killing; aim for free drug concentrations above the MIC for approximately 40% of the dosing interval (40% fT>MIC) 8. For critically ill patients or resistant organisms (MIC ≥4 mg/L), consider extended infusions (3 hours) or continuous infusion to achieve 100% fT>MIC 9.
When to use meropenem: Reserve for suspected/confirmed ESBL-producing Enterobacteriaceae or multidrug-resistant Gram-negative organisms 2, 10. Third-generation cephalosporins (ceftriaxone/cefotaxime) remain first-line for most bacterial meningitis 2.
Therapeutic drug monitoring: In culture-negative meningitis or treatment failure, measure creatinine clearance via timed urine collection (not just calculated estimates) to detect ARC, which can cause subtherapeutic levels despite normal serum creatinine 5. TDM-guided dosing is critical in these scenarios.