Pharmacokinetics and pharmacodynamics of linezolid in plasma/cerebrospinal fluid in patients with cerebral hemorrhage after lateral ventricular drainage by Monte Carlo simulation

Objective: We investigated the pharmacokinetic (PK) and pharmacodynamic (PD) parameters of linezolid in patients who had suffered cerebral hemorrhage after lateral ventricular drainage.

Materials and methods: Ten patients with cerebral hemorrhage after lateral ventricular drainage with stroke-associated pneumonia who were given linezolid were enrolled. Plasma and cerebrospinal fluid (CSF) samples were taken at appropriate intervals after the first administration of linezolid and assayed by high-performance liquid chromatography (HPLC). Then, PK parameters were estimated, and a Monte Carlo simulation was used to calculate the probability of target attainments (PTAs) for linezolid achieving the PK/PD index at different minimal inhibitory concentrations (MICs).

Results: The maximum concentration of linezolid in plasma and CSF was reached at 1.00 h and 3.10 h, respectively. The average penetration of linezolid in CSF was 56.81%. If the area under the plasma concentration vs time curve from zero to the final sampling time (AUC_{0-24 h})/MIC ≥ 59.1 was applied as a parameter, the PTA of linezolid in plasma could provide good coverage (PTA ≥ 90%) only for pathogens with a MIC of ≤2 μg/mL, whereas it could be achieved in CSF with a MIC of ≤1 μg/mL. If %T > MIC ≥ 40% was applied as a parameter, the PTA of linezolid in plasma/CSF could provide good coverage if the MIC was ≤4 μg/mL.

Conclusions: For patients with Infection of the central nervous system and who are sensitive to the drug, the usual dosing regimens of linezolid can achieve a good therapeutic effect. However, for critically ill or drug-resistant patients, an increase in dose, the frequency of administration, or longer infusion may be needed to improve the curative effect.