Development of a pharmacokinetic/pharmacodynamic evaluation model for osteomyelitis and usefulness of tedizolid as an alternative to vancomycin against MRSA osteomyelitis.

OBJECTIVES

This study aimed to develop a suitable osteomyelitis model for pharmacokinetic/pharmacodynamic (PK/PD) evaluation and to investigate the target PK/PD values of vancomycin and tedizolid against methicillin-resistant Staphylococcus aureus (MRSA) osteomyelitis.

METHODS

An osteomyelitis model was established by implanting an MRSA-exposed sterilized suture in the tibia of normal mice and mice with cyclophosphamide-induced neutropenia. The suitability of the osteomyelitis mouse model for PK/PD evaluation was assessed using vancomycin as an indicator. The target PK/PD values for tedizolid were determined using this model.

KEY FINDINGS: In neutropenic mice, to achieve a static effect and 1 log10 kill against MRSA, the ratios of the area under the free drug concentration-time curve for 24 h to the minimum inhibitory concentration (fAUC24/MIC) of vancomycin were 91.29 and 430.03, respectively, confirming the validity of the osteomyelitis model for PK/PD evaluation. In immunocompetent mice, the target fAUC24/MIC values of tedizolid for achieving a static effect and 1 log10 kill against MRSA were 2.40 and 49.20, respectively. Additionally, only a 0.28 log10 kill was achieved in neutropenic mice with 20 times the human equivalent dose of tedizolid.

CONCLUSIONS

In patients with restored immunity, tedizolid can potentially be used as an alternative to intravenous vancomycin therapy.