MUTUAL INTERACTIONS BETWEEN DICLOFENAC DIETHYLAMINE AND PHOSPHOLIPIDS- INVESTIGATIONS ON THE MICROSTRUCTURE OF THE ARISEN SYSTEMS

Among the group of the nonsteroidal anti-inflammatory drugs, there is a number of substances showing lyotropic liquid crystalline behaviour. Diclofenac diethylamine (DD) is such an amphiphilic drug molecule whi ch is able to form lyotropic liquid crystals in the presence of water. The addition of phospholipids leads to interactions between these two amphiphilic molecules. Depending on the ratio of DD to phospholipids and water, lamellar liquid crystalline structures, multilamellar vesic les, isotropic gels, microemulsions and mixed phases of these structur es arise. A ternary phase diagram is established in the region of 0-20 % DD, 0-20% phospholipids and 80-100% water. The preparations are inve stigated macroscopically, by polarized light microscopy and by transmi ssion electron microscopy. In systems with higher content of phospholi pids the interactions between the drug molecule and phospholipids are investigated by small angle x-ray diffraction. The thickness of the la mellar interlayer spacing of phospholipids decreases with the addition of drug. In diluted liposome systems interactions are cleary found by fluorescence studies.