Incorporation rates, stabilities, cytotoxicities and release of liposomal tetracycline and doxycycline in human serum

Tetracycline and doxycycline were encapsulated In cationic, anionic and neu tral liposomes. The amounts of antibiotic encapsulated, the stability of ea ch preparation at 4 degrees C for 4 weeks, and the kinetics of the release of entrapped drug into human sera were assessed lay highperformance liquid chromatography. The toxicities of the liposome preparations on human erythr ocytes and HeLa 229 cells were evaluated in vitro. The results showed that doxycycline was entrapped more efficiently than tetracycline, and that doxy cycline-entrapped liposomes were more stable at 4 degrees C and in human se ra, and less cytotoxic than tetracycline-entrapped liposomes.