Supercritical assisted process for the efficient production of liposomes containing antibiotics for ocular delivery

Conventional techniques developed for the production of liposomes for ocular delivery show low encapsulation efficiencies (EE). In this work, a supercritical CO2 based one-step continuous process, named Supercritical Assisted Liposome formation (SuperLip), was used for the production of liposomes to deliver ophthalmic antibiotics, such as ampicillin and ofloxacin. Micrometric and sub-micrometric liposomes with mean diameters in the range from 280 ± 104 nm to 1.76 ± 0.79 μm were successfully produced using drug concentrations in the range from 1% to 6% w/w and water to lipid ratios from 1.7 mg/g to 25 mg/g. Encapsulation efficiencies up to 97% and 99% were obtained for ofloxacin and ampicillin respectively. Storage stability and drug release kinetics of produced liposomes were also studied. Liposomes were stable for at least 3 months, with negligible drug leakage during storage time. At 37 °C ofloxacin and ampicillin were released in a controlled manner within 3 and 4 h respectively.