Methods
With the previously validated model developed by Klastrup et al., two different methodological approaches were used to evaluate the impact of piperacillin unbound fraction variations. In the first approach, we evaluated the predictive performance of this model in multiple simulated scenarios of unbound concentrations within a dataset from a previous study [10]. This dataset contained total concentration values of piperacillin. In the second approach, subjects were selected from the dataset based on certain criteria to assess the impact of unbound fraction variations on target attainment of piperacillin.