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

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.