Simplified daptomycin dosing regimen for adult patients with methicillin-resistant Staphylococcus aureus infections based on population pharmacokinetic analysis.

Daptomycin is used to treat methicillin-resistant Staphylococcus aureus (MRSA) infections. Current guidelines recommend higher daptomycin doses (8-10 mg/kg) for severe infections; however, pharmacokinetic (PK) and pharmacodynamic-based dosing strategies are still limited. Therefore, we designed a new optimal daptomycin dosing regimen for patients with MRSA infections using a population PK modeling approach. A total of 110 plasma concentrations from 47 adult patients who received daptomycin in general wards were enrolled for population PK modeling. The target area under the concentration-time curve/minimum inhibitory concentration (MIC) ratio, target peak/MIC ratio, and threshold of the trough concentration for safety were set to >666, >60, and 24.3 mg/L, respectively. Renal function was indicated as a significant covariate for daptomycin clearance. The simulated probability of target attainment was more than 90% at MIC values of 0.25 and 0.5 mg/L in all patients at the standard dose (6 mg/kg). In contrast, comprehensive simulation assessments recommended 10 mg/kg every 24 h in patients with creatinine clearance >60 mL/min for MIC values of 1.0 mg/L. We propose a new simplified daptomycin dosing regimen stratified by renal function and MIC values based on PK model-based simulation analyses. The proposed regimen is expected to maximize clinical efficacy and minimize adverse events.