Modifying the release properties of liposomes toward personalized medicine.

Surfactant-liposome interactions have historically been investigated as a simplified model of solubilization and breakdown of biological membranes by surfactants. In contrast, our goal was to utilize surfactants to modify the encapsulation and release properties of liposomes. The ability to manufacture one liposomal formulation, which could be modified by the addition of a surfactant to support a wide range of release profiles, would provide greater flexibility than manufacturing multiple batches of liposomes, each differing in composition and with its own specific release profile. A liposomal ciprofloxacin formulation was modified by the addition of various surfactants. These formulations were characterized in terms of liposome structure by cryo-TEM imaging, vesicle size by dynamic light scattering, drug encapsulation by centrifugation-filtration, and in vitro release (IVR) performance. The addition of polysorbate 20 or polysorbate 80 to liposomal ciprofloxacin, in a hypotonic environment, resulted in a concentration-dependent loss of encapsulated drug, and above 0.4% polysorbate 20, or 0.2% polysorbate 80, a modified IVR profile as well. This study demonstrates that the encapsulation and release properties of a liposomal formulation can be modified postmanufacture by the addition of judiciously chosen surfactants in combination with osmotic swelling of the liposomes and may support a personalized approach to treating patients.