Thermodynamical and Structural Effects of Diltiazem on Lecithin Liposomes

In the present work the structural and thermodynamical modifications induced by the calcium antagonist drug diltiazem, on DPPC liposomes, considered as model of the lipid matrix of the cell membrane, have been studied, by using differential scanning calorimetry, x-ray diffraction and optical microscopy techniques. Calorimetric scans and X-ray diffraction patterns show that, at higher concentration of diltiazem, the pretransition peak disappears, the main transition temperature decreases, the lamellar thickness increases and the chains, in the β conformation, are packed in a hexagonal undistorted lattice. Finally for higher concentrations of diltiazem the liquid crystalline phase with melted chains seems to become hexagonal.