title: Tuning Ciprofloxacin Release Profiles from Liposomally Encapsulated Nanocrystalline Drug.
abstract: In order to attenuate the drug release rate, a single freeze-thaw step was previously shown to convert encapsulated drug into a single nanocrystal within each liposome vesicle. The goal of this study was to alter the nanocrystalline character, and thus the drug encapsulation state and release profile, by addition of surfactant prior to freeze-thaw.
  
  
  
  A liposomal ciprofloxacin (CFI) formulation was modified by the addition of surfactant and frozen. After thawing, these formulations were characterized in terms of drug encapsulation by centrifugation-filtration, liposome structure by cryo-TEM imaging, vesicle size by dynamic light scattering, and in vitro release (IVR) performance.
  
  
  
  The addition of increasing levels of polysorbate 20 (0.05 to 0.4%) or Brij 30 (0.05 to 0.3%) to the CFI preparations followed by subsequent freeze-thaw, resulted in a greater proportion of vesicles without drug nanocrystals and reduced the extent of growth of the nanocrystals thus leading to modified release rates including an increase in the ratio of non-encapsulated to sustained release of drug.
  
  
  
  This study provides another lever to achieve the desired release rate profile from a liposomal formulation by addition of surfactant and subsequent freeze-thaw, and thus may provide a personalized approach to treating patients.
authors.affiliation: Advanced Drug Delivery Group, Faculty of Pharmacy, The University of Sydney, Pharmacy Building A15, Sydney, NSW, 2006, Australia. cipollad@aradigm.com.|Aradigm Corporation, 3929 Point Eden Way, Hayward, California, 94545, USA. cipollad@aradigm.com.
authors.forename: David
authors.initials: D
authors.lastname: Cipolla
authors.affiliation: Aradigm Corporation, 3929 Point Eden Way, Hayward, California, 94545, USA.
authors.forename: Huiying
authors.initials: H
authors.lastname: Wu
authors.affiliation: ProNAi Therapeutics, Inc., 2150 - 885 W. Georgia St., Vancouver, British Columbia, V6C 3G1, Canada.
authors.forename: Simon
authors.initials: S
authors.lastname: Eastman
authors.affiliation: Northern Lipids Inc, 8855 Northbrook Court, Burnaby, British Columbia, Canada, V5J 5J1.
authors.forename: Tom
authors.initials: T
authors.lastname: Redelmeier
authors.affiliation: Aradigm Corporation, 3929 Point Eden Way, Hayward, California, 94545, USA.
authors.forename: Igor
authors.initials: I
authors.lastname: Gonda
authors.affiliation: Advanced Drug Delivery Group, Faculty of Pharmacy, The University of Sydney, Pharmacy Building A15, Sydney, NSW, 2006, Australia.
authors.forename: Hak-Kim
authors.initials: HK
authors.lastname: Chan
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry*; D002626:Chemistry, Pharmaceutical; D002939:Ciprofloxacin / Q000737:chemistry*; D065546:Drug Liberation; D005615:Freezing; D006801:Humans; D008081:Liposomes / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D011136:Polysorbates / Q000737:chemistry; D012995:Solubility; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry
chemical_list: D000900:Anti-Bacterial Agents; D008081:Liposomes; D011136:Polysorbates; D013501:Surface-Active Agents; D002939:Ciprofloxacin
keywords: in vitro release; liposome; nanocrystal; personalized medicine; surfactant