BACKGROUND: Two studies in hydrocephalic children and adolescents were performed to assess the penetration of linezolid into cerebrospinal fluid and its relation to meningeal inflammation. METHODS: Each patient was administered intravenous linezolid 10 mg/kg every 12 hours for 3 days (study 1) or every 8 hours for 2 days (study 2). Pharmacokinetic indices (Cmax, Cmin, Tmax, AUC) were determined for plasma and ventricular fluid (VF) after the first and last doses. RESULTS: In study 1, after the last dose, the mean Cmax values for plasma and VF were 10.30 microg/mL (range, 3.95-16.6 microg/mL) and 7.54 microg/mL (range, 2.26-12.6 microg/mL), respectively; mean Cmin values were 1.32 microg/mL (range, 0.08-3.66 microg/mL) and 1.26 microg/mL (range, 0.19-2.58 microg/mL), respectively. The VF:plasma ratio based on last dose AUC0-12 was 0.98 microg h/mL (range, 0.64-1.22 microg h/mL). In study 2, after the last dose, the mean plasma and VF Cmax levels were 9.83 microg/mL (range, 3.19-16.5 microg/mL) and 5.84 microg/mL (range, 1.82-9.34 microg/mL), respectively; mean plasma and VF Cmin levels were 1.12 microg/mL (range, 0.10-3.39 microg/mL) and 1.94 microg/mL (range, 0.34-4.62 microg/mL), respectively. The VF:plasma ratio based on last dose AUC0-8 was 0.95 microg h/mL (range, 0.62-1.31 microg h/mL). Inflammation of the meninges did not seem to influence penetration of linezolid to the VF. CONCLUSIONS: : Both studies showed that VF concentrations were variable. Further investigation of the role of linezolid in the treatment of CNS infection is needed.