Membrane Based Lipid-Drug Interaction

The action of drugs an living systems is a membrane-based process. Their interaction at the membrane surface/interior and transport through it induces a change in the physical properties of the membrane, of which fluidity is among the most important ones. The lipophilic drugs can affect this fluidity directly through their incorporation into the lipid matrix, whereas the action of the hydrophilic drugs is confined mostly at the membrane-water interface. Using the liposomal membranes of dipalmitoyl phosphatidyl choline, a comparative study of the effect of a hydrophilic drug, chloroquine sulphate, and a lipophilic drug, hydrocortisone, on the membrane fluidity, measured in terms of anisotropy, is presented. From the membrane anisotropy-temperature curve, the associated enthalpy change has been calculated. Results show that the two drugs affect the membrane order in two different ways, indicating that there is a difference in the interaction of these two drugs with the liposomal membrane at the molecular level.