Evaluation of pharmacokinetic target attainment and hematological toxicity of linezolid in pediatric patients

Linezolid is commonly used to treat severe and/or resistant Gram-positive infections. Few studies have assessed its pharmacokinetic (PK) target attainment in pediatrics.

To evaluate the percentage of pediatrics achieving the PK targets of linezolid with standard dosing regimens and to assess the incidence and risk factors associated with its hematologic toxicity.

This prospective observational study included pediatric patients aged 0–14 who received linezolid for suspected or proven Gram-positive infections. Linezolid trough concentrations and the 24-h area under the curve (AUC₂₄) were estimated, and hematologic toxicity was assessed.

Seventeen pediatric patients (5 neonates and 12 older pediatrics) were included. A wide variability was observed in linezolid’s trough and AUC₂₄ (ranging from 0.5 to 14.4 mg/L and from 86 to 700 mg.h/L, respectively). The median AUC₂₄ was significantly higher in neonates than older pediatrics (436 [350–574] vs. 200 [134–272] mg,h/L, P = 0.01). Out of all patients, only 41% achieved adequate drug exposure (AUC₂₄ 160–300 mg.h/L and trough 2–7 mg/L), with 24% having subtherapeutic, and 35% having higher-than-optimal exposures. Hematological toxicity was observed in 53% of cases. Identified risk factors include treatment duration over 7 days, baseline platelet counts below 150 × 10⁹/L, sepsis/septic shock, and concomitant use of meropenem.

Linezolid’s standard dosing failed to achieve its PK targets in approximately half of our pediatric cohort. Our findings highlight the complex interplay between the risk factors of linezolid-associated hematological toxicity and underscore the importance of its vigilant use and monitoring, particularly in pediatrics with concomitant multiple risk factors.