Clinical efficacy and safety assessment of tedizolid using therapeutic drug monitoring

Thrombocytopenia derived from tedizolid (TZD) has been reported but less frequently than that from linezolid. Only a few reports have investigated the relationship between the efficacy and safety of TZD administration. This study aimed to measure TZD concentration and investigate the relationship between efficacy and safety. The study was conducted at the Aichi Medical University Hospital. All patients administered TZD were included; the serum trough concentration (Cmin) of TZD was measured using LM1010 high-performance liquid chromatography. Efficacy was assessed as clinical and microbiological efficacy. Clinical efficacy was defined as no recurrence and no need for additional treatment until 2 weeks after the end of TZD therapy. Microbiological efficacy was defined as the absence of bacteria during and after TZD therapy. Safety was assessed using thrombocytopenia. Thrombocytopenia was defined as a decrease in platelet count of ≥25% compared with baseline levels and a minimum count of <10 × 10⁴/μL. Seventeen patients were included. The Cmin in 16 patients was <0.5 μg/mL; one patient had a Cmin of 1.01 μg/mL complicated by hepatic cirrhosis. Clinical and microbiological efficacy was found in >80% of the patients. Thrombocytopenia occurred in 14.3% (2/14) of the patients. The Cmin in two patients with thrombocytopenia were 0.14 and 0.28 μg/mL, respectively. The serum concentration of TZD might increase in patients with hepatic cirrhosis; therapeutic drug monitoring may be required. Thrombocytopenia due to TZD could occur regardless of its serum concentration, necessitating monitoring for platelet count.