Linezolid‐Induced Lactic Acidosis: Avoiding Concomitant Use With Metformin and Monitoring Linezolid Trough Concentration

Objective: Serum lactic acidosis has been reported as a serious adverse effect associated with linezolid. This study aims to explore the risk factors of linezolid‐induced lactic acidosis. Methods: Patients admitted to a 3600‐bed university hospital, who received linezolid treatment and had at least one steady‐state concentration of linezolid, were retrospectively reviewed to analyze the incidence of linezolid‐induced lactic acidosis. Meanwhile, univariate and multivariate logistic regression analyses were conducted to determine the risk factors of lactic acidosis. Results: A total of 95 adult patients were included in the study. 18.95% (18 out of 95) of patients developed lactic acidosis during linezolid treatment. Importantly, patients who concurrently used linezolid and metformin had a high risk of developing lactic acidosis (90.9%, 10 out of 11). After excluding these patients from the original database, 9.52% (8 out of the 84) of the patients developed lactic acidosis. In the population not receiving concurrent metformin treatment, univariate analysis showed that patients who developed lactic acidosis had higher linezolid C min and serum creatinine levels or lower creatinine clearance, and multivariate analysis showed that C min (OR: 1.114; 95% CI: 1.012–1.226; p = 0.027) was an independent risk factor for lactic acidosis. Conclusion: The concurrent use of linezolid and metformin raises the risk of lactic acidosis. Therapeutic drug monitoring of linezolid based on C min is recommended for decreasing the risk of lactic acidosis during linezolid treatment.