Physical Chemistry of Drug Permeation through the Cell Membrane with Atomistic Detail

We provide a molecular-level description of the thermodynamics and mechanistic aspects of drug permeation through the cell membrane. As a case study, we considered the anti-malaria, FDA approved drug chloroquine. Molecular dynamics simulations of the molecule (in its neutral and protonated form) were performed in the presence of different lipid bilayers, with the aim of uncovering key aspects of the permeation process, a fundamental step for drugs action. Free energy values obtained by well-tempered metadynamics simulations suggest that the neutral form is the only permeating protomer, consistent with experimental data. H-bond interactions of the drug with water molecules and membrane headgroups play a crucial role for permeation. The presence of the transmembrane potential, investigated here for the first time in a drug permeation study, does not qualitatively affect these conclusions. TOC Graphic O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/550356v1_ufig1.gif" ALT="Figure 1"> View larger version (71K): org.highwire.dtl.DTLVardef@d1f5b9org.highwire.dtl.DTLVardef@5b6b0forg.highwire.dtl.DTLVardef@1d1b55borg.highwire.dtl.DTLVardef@d96b52_HPS_FORMAT_FIGEXP M_FIG C_FIG