A target-based population pharmacokinetic and pharmacodynamic analysis for intra-articular dosing regimen...

Although intra-articular vancomycin has demonstrated satisfactory outcomes for periprosthetic joint infection (PJI), dose and dosing frequency remain largely empirical. This study aimed to develop a target-based population pharmacokinetics (PK) model to predict local vancomycin exposure, and to evaluate the efficacy and safety of various regimens in patients with PJI.

Patients with PJI who received intravenous (IV) infusion or intra-articular injection of vancomycin were included. Population PK analysis was performed using nonlinear mixed effects modelling. Monte Carlo simulations were used to assess pharmacodynamic target attainment against Staphylococcus species, and to evaluate vancomycin-associated safety risks.

A total of 450 plasma and synovial fluid samples from 161 patients with PJI were analyzed. The pharmacokinetics of vancomycin in synovial fluid were best described by a two-compartment joint model linked to a central plasma compartment. Creatinine clearancesignificantly affected systemic clearance, while age influenced the penetration from synovial fluid to the central compartment. Simulations suggested that intra-articular dosing of 500 mg once daily was sufficient for targets against Staphylococcus aureus and Staphylococcus epidermidis, whereas other coagulase-negative staphylococci required more intensive regimens, including 250 or 500 mg every 12 hours or 1,000 mg once daily. For patients with severe renal impairment, intra-articular administration alone provided adequate systemic exposure, and concomitant IV administration was not recommended.

The intra-articular population PK model accurately characterized vancomycin concentrations in plasma and synovial fluid, supporting optimized intra-articular dosing regimens in patients with PJI according to renal function and age.