Interaction of sodium diclofenac with freeze-dried soya phosphatidylcholine and unilamellar liposomes

Abstract

Phospholipids are widely used as structural amphiphilic compounds in liposome formulations. In this study, we have analyzed the interaction the sodium diclofenac (SD) with soya phosphaditylcholine (PC) and soya phosphatidylcholine from lyophilized small unilamellar liposomes (SUV). The changes in the properties of the co-lyophilized drug/PC from SUV liposomes, lyophilized PC from SUV liposomes, and lyophilized soya phosphatidylcholine, were studied by Differential Scanning Calorimetry (DSC). The DSC data showed that the previous organization of phospholipids molecules to form liposome affects intensely the thermal behavior of PC when compared to non-lipossomal PC. SD modified the thermal properties of PC from liposomes. It was verified that SD affects intensely the located group peaks in the regions of 120-140 ºC and in the higher temperature region of 240-260 ºC. The results of this work demonstrated that the presence of the drug modified the DSC behavior for both liposomal and non-liposomal PC and that these modifications can be easily monitored by DSC analysis.