The relatively weak binding of metal cations (also other than sodium and calcium ) with a distinct mechanism to PC membranes suggests that they probably do not interfere with the binding of charged drugs with higher affinities, such as etidocaine, dibucaine and SMS. The situation may be more complex for molecules with similar binding affinities but the different mechanism, such as calcium and TPP. While MD simulations are a promising tool to model such complicated systems, the accuracy of current force fields is not sufficient for such applications as none of the available force fields correctly captures both the calcium and charged small molecule binding to membranes.