Encapsulation of a quinolone in liposomes. Location and effect on lipid bilayers

In Vitro Evaluation of Enrofloxacin-Loaded MLV Liposomes

Fluoroquinolones are broad-spectrum antimicrobial agents that seem to reach their intracellular target site (DNA gyrase) in Escherichia coli by means of an uptake process through the outer and inner membranes. Delivery of quinolones with liposomes has many advantages than the free form of the drug. Liposomes may represent an excellent device for improving the selective transport of antibiotics in these respects. In this study, enrofloxacin-loaded multilamellar vesicles (MLVs) were prepared and the effects of formulation variables on the liposome characteristics were investigated. Liposomes were prepared by using the dry lipid film method. A number of variables, such as phospholipid (DL-alpha -phosphatidylcholine dipalmitoyl), cholesterol, enrofloxacin (ENF), stearylamine, and dicetyl phosphate molar ratios and alpha -tocopherol amounts, were studied. The liposome size, encapsulation capacity, drug release, stability, and electrophoretic mobility of ENF-loaded liposomes were determined. Using this method, spherical MLVs with high drug content could be produced. Particle size of liposomes changed between 1.63 and 3.31 micro m and liposome size was affected by all formulation variables (p < 0.05) except molar ratio of ENF. MLVs can be used as a carrier system for the controlled release of ENF. The highest encapsulation of ENF amount can be obtained using positively charged SA in the formulation and changing the formulation parameters can vary drug release patterns.

Encapsulation of Enrofloxacin in Liposomes I: Preparation and In Vitro Characterization of LUV

Liposomes are effectively used in the treatment of microbial infections. Higher cellular uptake has been reported when antibiotics are encapsulated in liposomes. In this study, enrofloxacin (ENF) was encapsulated in large unilamellar vesicles (LUVs) and the effects of formulation variables on the liposome characteristics were investigated. Liposomes were prepared using dry lipid film method. A number of variables such as molar ratios of phospholipid (DPPC; DL-alpha-phosphatidylcholine dipalmitoyl), cholesterol, ENF and amount of alpha-tocopherol and the volumes of internal (chloroform) and external phases [phosphate buffered saline PBS (pH 7.4)] were studied. In vitro characterization of the liposomes including the encapsulation capacity, size and drug release properties were carried out. Using of this method, spherical LUV liposomes with high drug content could be produced. Particle size of liposomes changed between 3.12 and 4.95 microm. The molar ratios of DPPC, cholesterol and ENF affected the size of the liposome (p < 0.05). The drug encapsulation capacities were high and changed between 37.1% and 79.5%. The highest ENF encapsulation was obtained with the highest cholesterol content. An increase in the drug encapsulation capacity of the liposome was found with increasing molar ratios of DPPC, cholesterol and ENF (p < 0.05). Furthermore, the release of ENF from the liposomes decreased as the molar ratios of DPPC, cholesterol and ENF increased (p < 0.05). In conclusion, a convenient colloidal carrier for the controlled release of ENF can be prepared by changing the formulation parameters of LUVs.