Pharmacokinetic-pharmacodynamic modeling of dalbavancin, a novel glycopeptide antibiotic.

Dalbavancin is a novel glycopeptide with a 2-dose, once-weekly dosing regimen that is being developed for the treatment of complicated skin and skin structure infections caused by gram-positive bacteria. Monte Carlo simulations were performed for dalbavancin using population pharmacokinetic data and minimum inhibitory concentrations (MICs) for clinical trial isolates. The time-dependent target was the maintenance of free drug concentrations above the MIC for 14 days (t>MIC). The concentration-dependent target was an area under the concentration-time curve (AUC)/MIC ratio of approximately 1000 for Staphylococcus aureus and 100 for Streptococcus sp. These targets were used to estimate susceptibility breakpoints for dalbavancin. For S aureus, the estimated susceptibility breakpoint was <or=0.5 microg/mL using AUC(14 days)/MIC and <or=1 microg/mL using t>MIC. For Streptococcus sp, the estimated susceptibility breakpoint was at least 2 mug/mL. Because dalbavancin MIC(90)s for these species are well below these values, the analysis supports the use of once-weekly dosing regimens of dalbavancin in the treatment of complicated skin and skin structure infections.