Linezolid Serum Concentration Variability Among Critically Ill Patients Based on Renal Function and Continuous Renal...

Area of Science:

• Pharmacokinetics and Pharmacodynamics
• Critical Care Medicine
• Infectious Diseases

Background:

• Standard linezolid dosing is often used in intensive care units (ICUs) without adjustment for renal impairment.
• Variability in linezolid serum concentrations based on renal function and continuous renal replacement therapy (CRRT) is not well understood.
• This study investigates linezolid pharmacokinetics in critically ill patients with varying renal function and CRRT status.

Purpose of the Study:

• To examine the variability of linezolid serum concentrations in ICU patients.
• To assess the impact of renal function and CRRT on linezolid levels.
• To determine the adequacy of standard linezolid dosing in specific patient populations.

Main Methods:

• Retrospective, single-center observational study.
• Inclusion of ICU patients receiving 1200 mg/day linezolid with renal function and trough therapeutic drug monitoring (TDM) data.
• Stratification based on renal function (including severe impairment) and CRRT status (CVVH).

Main Results:

• CRRT patients had higher median linezolid concentrations (4.6 mg/L) than non-CRRT patients (3.2 mg/L), with lower underdosing risk (17% vs. 39%).
• Compared to non-CRRT patients with renal function ≤ 30 mL/min, CRRT patients showed significantly lower concentrations (4.6 mg/L vs. 10 mg/L) and fewer out-of-range levels.
• Inverse correlation between renal function and linezolid levels (Spearman's rho = -0.61, p < 0.001); continuous infusion led to higher concentrations and increased overdose risk.

Conclusions:

• Linezolid levels exhibit wide variability in critically ill patients, influenced by renal function and CRRT.
• Severe renal impairment increases overdose risk, while acute renal failure (ARF) may lead to underdosing; standard dosing may be adequate in CRRT patients.
• Therapeutic drug monitoring (TDM)-guided personalized dosing is essential for optimizing linezolid therapy, minimizing toxicity, and preventing treatment failure.