[Research on the pharmacokinetics of linezolid in burn patients]

Objective: To explore the pharmacokinetic characteristic of linezolid in burn patients and its influencing factors. Methods: This study was a retrospective cohort study. From August 1^st, 2024 to August 1^st, 2025, 74 burn patients who were admitted to the Department of Burn of Ruijin Hospital of Shanghai Jiao Tong University School of Medicine, received linezolid treatment under the standard dosing regimen of 600 mg every 12 hours, and completed monitoring of plasma trough concentration of linezolid (hereinafter referred to as plasma trough concentration), were included as burn group, including 22 males and 52 females, aged 16-87 years, with a total of 81 plasma trough concentration measurements. During the same period, 74 patients with pulmonary infection who were admitted to the Department of Critical Care Medicine of the same hospital, received the same linezolid treatment, and completed monitoring of plasma trough concentration, were included as pulmonary infection group, including 51 males and 23 females, aged 23-90 years, with a total of 75 plasma trough concentration measurements. The plasma trough concentrations of patients in two groups were detected at 30 min before the fifth administration using liquid chromatography-tandem mass spectrometry. In burn group of patients, the correlations between the plasma trough concentration and age, body weight, total burn area, full-thickness burn area, admission time after burn, serum albumin level, serum creatinine level, and creatinine clearance rate were analyzed. In pulmonary infection group of patients, the correlations between the plasma trough concentration and age, body weight, serum albumin level, serum creatinine level, and creatinine clearance rate were analyzed. The interaction of plasma trough concentration with age, body weight, serum albumin level, and serum creatinine level in two groups of patients were analyzed. Results: The plasma trough concentration in burn group of patients was 2.30 (0.65, 5.70) mg/L, which was significantly lower than 4.07 (2.01, 7.82) mg/L in pulmonary infection group (Z=-3.131, P<0.05). The proportion with plasma trough concentration <2 mg/L in burn group of patients was 46.91% (38/81), which was significantly higher than 22.67% (17/75) in pulmonary infection group (χ²=10.030, P<0.05). In burn group of patients, the plasma trough concentration was significantly positively correlated with age (rs=0.483, P<0.05), and significantly negatively correlated with body weight and full-thickness burn area (with rs values of -0.247 and -0.231, respectively, P<0.05). In pulmonary infection group of patients, the plasma trough concentration was significantly negatively correlated with creatinine clearance rate (rs=-0.344, P<0.05), and significantly positively correlated with serum creatinine level (rs=0.255, P<0.05). In both pulmonary infection group and burn group of patients, the plasma trough concentration showed a significant interaction with the serum albumin level (with β values of 0.201 and -0.145, respectively, 95%CI of -0.085 to 0.488 and -0.344 to 0.055, respectively, P<0.05). Conclusions: Under the standard dosing regimen of linezolid, the plasma trough concentration in patients with burns was significantly lower than that in patients with pulmonary infection, and the proportion of low drug exposure was higher. In patients with burns, the plasma trough concentration was correlated with age, body weight, and full-thickness burn area. The plasma trough concentration in both patients with burns and patients with pulmonary infection showed a significant interaction with the serum albumin level.