However, we did not observe any permeation events of etidocaine or TPP through the membrane. This is in contrast to water molecules, for which dozens of events were observed in each simulation. This can be explained by the larger size of etidocaine and TPP molecules increasing their probability to locate at the membrane centre without permeating through the membrane. While we consider these observations as reasonable interpretations of the experimental data with the best available MD simulation models, we emphasize that the detailed interactions in these simulations may not be exactly correct since the β-carbon order parameter response to studied charged molecules was not in agreement with the experiment in Fig. .