Vancomycin Dosing for Meningitis
For bacterial meningitis, administer vancomycin at 15-20 mg/kg IV every 8-12 hours (not every 6 hours as sometimes used for MRSA meningitis), targeting trough concentrations of 15-20 μg/mL, and strongly consider adding rifampin due to concerns about vancomycin's poor CSF penetration, especially when dexamethasone is co-administered. 1
Standard Dosing Regimen
- Administer 15-20 mg/kg (actual body weight) IV every 8-12 hours for adults with normal renal function 1, 2
- For pediatric patients, use 15 mg/kg/dose IV every 6 hours 1
- Do not use fixed 1 g doses—weight-based dosing is mandatory as fixed dosing leads to underdosing in most patients, particularly those >70 kg 2, 3
Loading Dose for Meningitis
- Administer a loading dose of 25-30 mg/kg (actual body weight) for all patients with suspected or confirmed bacterial meningitis to rapidly achieve therapeutic concentrations 2, 3
- Infuse the loading dose over 2 hours and consider premedication with an antihistamine to reduce red man syndrome risk 2, 3
- The loading dose is NOT affected by renal function—only maintenance doses require adjustment 2, 3
Critical Adjunctive Therapy
- Strongly consider adding rifampin 600 mg once daily or 300-450 mg twice daily to vancomycin for adult patients with meningitis 1
- This combination is particularly important because vancomycin penetration into adult CSF is poor, especially when dexamethasone is co-administered 1
- For penicillin-resistant pneumococcal meningitis, vancomycin should never be used as monotherapy 1
Therapeutic Monitoring
- Target trough concentrations of 15-20 μg/mL for meningitis 1, 2
- Obtain trough levels before the fourth or fifth dose to ensure steady-state conditions 2, 3
- The pharmacodynamic target is an AUC/MIC ratio >400, which best predicts efficacy 2, 3
Important Clinical Considerations
CSF Penetration Issues
- Vancomycin CSF penetration is highly variable and inflammation-dependent—penetration is approximately 48% with active meningitis but only 18% without significant inflammation 4
- In mild or healthcare-associated meningitis with low CSF protein levels, vancomycin may not achieve adequate CSF concentrations even with appropriate serum levels 5
- Dexamethasone administration further impairs vancomycin CSF penetration, making rifampin addition even more critical 1
When to Consider Alternatives
- If vancomycin MIC is ≥2 μg/mL, switch to alternative agents (linezolid, TMP-SMX) as target AUC/MIC ratios are not achievable 1, 2
- For healthcare-associated meningitis with mild inflammation, consider antibiotics with better CSF penetration as first-line therapy rather than vancomycin 5
- Linezolid 600 mg PO/IV twice daily is an alternative for MRSA meningitis with better CSF penetration 1
Common Pitfalls to Avoid
- Never use vancomycin monotherapy for meningitis—always combine with rifampin or use an alternative agent 1
- Avoid targeting only serum trough levels without considering CSF penetration, particularly in patients receiving dexamethasone 1
- Do not assume adequate CSF levels based on serum concentrations alone—CSF penetration is unpredictable and inflammation-dependent 4, 5
- Sustained trough concentrations >20 μg/mL increase nephrotoxicity risk, so monitor renal function closely 2, 6
- In healthcare-associated meningitis with minimal inflammation, vancomycin may fail despite adequate dosing due to poor CSF penetration 5