Interactions Of Fenspiride- And Azithromycin-Loaded Liposomes With Model Lipid Membranes: Calorimetric Studies In Kinetic Regime

Differential scanning calorimetry (DSC) technique was applied to study interactions of drug-loaded liposomes with model lipid membrane. Two types of drugs were studied, namely, water-soluble one (anti-inflammatory drug fenspiride, FS) and lipid-soluble one (antibiotic azithromycin, AZ) with different mechanisms of drug-membrane interactions. Drug transfer from the liposomes based on L-a-dipalmitoylphosphatidylcholine to L-alpha-dimirystoylphosphatidylcholine membranes was monitored by analyzing DSC profiles of the systems obtained in consecutive scans. It was shown that FS-loaded liposomes have weaker membranotropic effect as compared to FS water solution of equal FS concentrations. For both FS and AZ, relatively fast drug transfer from liposomes into model membrane was accompanied by slower lipid exchange between these structures. Similar transfer rates were shown for both drugs despite the fact that AZ transfer is mainly membrane-mediated, whereas FS transfer is primarily water-mediated.