We also tested the permeability of two very large compounds, MP18 and MP19 (see Figure for structures), which have molecular weights of 1071 Da and 1234 Da, respectively. Remarkably, even these >1000 Da compounds displayed moderate membrane permeability in the PAMPA (-logPe of 6.4 and 6.3, respectively). Taken together, these data suggest that IP+-containing MPs display much better membrane permeability than typical peptide macrocycles.